Frying technology and practices

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Frying/FM/wBluesChanges

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Frying Technology and Practices

Copyright 2004 by AOCS Press. All rights reserved.


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Frying Technology and Practices

Editors Monoj K. Gupta MG Edible Oil Consulting International Richardson, Texas

Kathleen Warner National Center for Agricultural Utilization Research U.S. Department of Agriculture Peoria, Illinois

Pamela J. White Department of Food Science Iowa State University Ames, Iowa

PostScript Picture AOCS press/logo

Champaign, Illinois



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AOCS Mission Statement To be the global forum for professionals interested in lipids and related materials through the exchange of ideas, information science, and technology. AOCS Books and Special Publications Committee M. Mossoba, chairperson, U.S. Food and Drug Administration, College Park, Maryland R. Adlof, USDA, ARS, NCAUR, Peoria, Illinois J. Endres, The Endres Group, Fort Wayne, Indiana T. Foglia, USDA, ARS, ERRC, Wyndmoor, Pennsylvania L. Johnson, Iowa State University, Ames, Iowa H. Knapp, Deaconess Billings Clinic, Billings, Montana A. Sinclair, RMIT University, Melbourne, Victoria, Australia P. White, Iowa State University, Ames, Iowa R. Wilson, USDA, REE, ARS, NPS, CPPVS, Beltsville, Maryland Copyright © 2004 by AOCS Press. All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means without written permission of the publisher. The paper used in this book is acid-free and falls within the guidelines established to ensure permanence and durability.

Library of Congress Cataloging-in-Publication Data Frying Technology and practices / editors, Monoj K. Gupta, Kathleen Warner, Pamela J. White p. cm. Includes bibliographical references and index. ISBN 1-893997-31-6 (hardcover : alk. paper) 1. Frying. 2. Oils and fats, Edible. I. Gupta, Monoj K. II. Warner, Kathleen. III. White, Pamela J. 612′.01577--dc21 TX689.F79 2004 641.7′7--dc22 2004003927

Printed in the United States of America. 08 07 06 05 04 5 4 3 2 1



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Preface

The frying of food products for culinary delight has been known to humans for centuries. Frying was one of the fastest ways to prepare foods. Most of the products were pan fried. The Chinese wok, Indian Kadai, and the Western frying pan were used for frying food at home. These early frying pans eventually evolved into kettles and fin a lly into the sophisticated continuous fryers of today. Precise moisture- and texture-controlling devices have been developed to fry diverse types of food products. These foods include sliced potatoes to make potato chips, sheeted and cut corn chips, extruded products, pellets that expand to large volumes and shapes, as well as batter-coated products, ranging from chicken, to fish, to various vegetables. Improved packaging techniques and packaging materials have increased the shelf life of various products, which has helped in their distribution. Partly dehydrated food (also known as par-fried) products, such as French fries and fried chicken, have reduced the cost and increased the production efficiency of food service and restaurant operations. The processes of extraction and refining of vegetable oil have improved significantly over the past three decades. During the same period, the oil-refining equipment and refining techniques have greatly improved. The oil processors are now able to deliver refined vegetable oils with higher quality and stability to the food industry. Numerous publications are available on frying that describe the effect of the frying process on the oil quality and flavor stability of the fried product. These publications constitute a tremendous source of information regarding the chemistry of frying oil and the fried food. Overall frying equipment, oil quality, packaging, and the distribution system have improved greatly. However, there has been very little advancement in the process of training personnel in the frying operation to improve their knowledge of the properties of the oil and the impact of frying on its degradation. Of all components in the frying operation, the oil has the greatest impact on the flavor stability of the fried product, plant personnel are insufficiently trained to apply appropriate techniques in a frying operation that would allow them to maintain the highest level of oil quality in the process. The personnel in a frying operation require a thorough understanding of the physical and chemical properties of the frying oil and the effect of the frying process on oil quality. This knowledge would enable them to protect the oil against undue damage, thus enabling them to avoid the operating techniques that can cause oil degradation in the frying process. An oil with a minimum amount of damage can deliver fried foods with high flavor stability. A number of books and technical papers have been published on frying. Most of them explain oil chemistry and degradation products of the oil. Some describe certain frying processes. This book is a unique compilation of theoretical discus-



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sions of oil chemistry and the mechanism of oil breakdown as well as the practical aspects related to frying. For example, this book includes: (i) basic frying-oil chemistry and the techniques for the protection of the frying oil; (ii) frying techniques involving coated foods; (iii) food safety and regulatory aspects related to frying and the practical issues; and (iv) the proper techniques required for the day-to-day operation of a frying process. Kathleen Warner and Pamela J. White have been known for many years as fundamental as well as applied researchers in the field of fats and oils. Ron Sassiela is a well-known scientist and author in the field of coated-food technology. David Firestone has been a renowned figure in the fats and oils area for many decades, Rick Stier is a food scientist who has devoted many years to understanding and assisting the frying industry. Finally, Monoj K. Gupta has had a long history in vegetable-oil processing as well as years of experience in the frying industry. His familiarity with vegetable-oil processing allowed him to develop an in-depth understanding of the frying process. He was able to envision opportunities to improve the shelf life of fried products by applying oil-quality management techniques that are applied in vegetable-oil processing to produce high-quality oil and to protect it against degradation. This accumulated experience along with specific techniques are discussed in several chapters of this book, culminating in the suggestion of practical solutions to numerous situations faced by frying operators and supervisors in their industry. Monoj K. Gupta Kathleen Warner Pamela J. White



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Contents

Chapter 1

Preface

Chapter 1 The Frying Industry Monoj K. Gupta Chapter 2 Chemical and Physical Reactions in Oil During Frying K. Warner Chapter 3 Selection of Frying Oil Monoj K. Gupta Chapter 4 Role of Antioxidants and Polymerization Inhibitors in Protecting Frying Oils Kathleen Warner, Caiping Su, and Pamela J. White Chapter 5 Procedures for Oil Handling in a Frying Operation Monoj K. Gupta Chapter 6 The Effect of Oil Processing on Frying Oil Stability Monoj K. Gupta Chapter 7 Critical Factors in the Selection of an Industrial Fryer Monoj K. Gupta, Russ Grant, and Richard F. Stier Chapter 8 Critical Elements in the Selection and Operation of Restaurant Fryers Monoj K. Gupta Chapter 9 Technology of Coating and Frying Food Products Ronald J. Sasiela Chapter 10 Fried Foods and Their Interaction with Packaging Kenneth S. Marsh Chapter 11 Toxicology of Frying Fats and Oils Richard F. Stier Chapter 12 Regulatory Requirements for the Frying Industry David Firestone


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Chapter 1

The Frying Industry Monoj K. Gupta MG Edible Oil Consulting International, 9 Lundy’s Lane, Richardson, TX 75080

Introduction: Historical Background Mankind has consumed fried food for centuries. Long ago, fried foods were prepared and consumed by the family at meal times or at gatherings with friends. Today, fried foods can be purchased in various forms. Shelf-stable packaged salty snack food has become common in every country. Fried foods are also served in restaurants, by food services, and at home. In the United States, nearly 2 billion pounds of oil is used annually for frying salty snack foods. The French fry manufacturers, breaded chicken and fish processors, as well as the restaurants and food services use several billion pounds of oil annually for frying. Freshly fried donuts, although not a salty snack, are popular as a snack or breakfast item. Fried salty snack food is a source of culinary delight throughout the world. The advanced countries in the West can provide some documents showing the origins of certain types of snack foods. Countries with old cultures and traditions have had snack foods for centuries but do not have any formal documentation showing when or how these products were introduced. For example, the people of India have consumed popped corn kernels for centuries. The corn was popped in a bed of hot sand. The people of the Indian subcontinent have used several other salty snack foods for centuries. These snack foods include nuts, grains, leguminous products, and extruded grains. Fried wafers were served on all social occasions in India. However, there are no documents showing the dates of origin for any of these products. The original inhabitants of North, Central and South America consumed fire-roasted corn and other vegetables. People in the Orient also have their indigenous snack foods but no historical data can be obtained to establish their source and the date of origin. United States of America. Probably the most documented snack food development can be traced in the United States. According to information recorded in the History of Snacks (1), the modern potato chip began as a joke in 1853 in a Saratoga Springs resort in New York. The railroad magnate Commodore Cornelius Vanderbilt was dining at the resort one evening when he sent the fried potatoes back to the kitchen because they were too thick. George Gum, the cook on duty, decided to thinly slice potatoes, deep fry and salt the fried chips. The chips were thin, crispy, and salty. What was meant to be a joke turned out to be the birth of



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modern day potato chips. The product was an instant hit. The Saratoga Chips became a fad with the resort’s socialite patrons. Soon the recipe spread throughout the eastern region of the country. In 1890, Cleveland entrepreneur, William Tappenden, started delivering potato chips that had been fried in his kitchen to the neighborhood stores. As the business grew, his barn became the first potato chip–producing factory in the country. Products were made in different parts of the country, and were delivered to the stores in sacks. It became apparent that this packaging could not protect the product well against moisture. In 1926, Laura Scudder first introduced potato chip bags. She and her employees used a hot iron to seal the edges of folded wax paper. They filled the formed bag and sealed the top in the same manner. Before this time, the retailers had to dispense potato chips from cracker barrels or large glass display jars. In 1933, the Dixie Wax Paper Company of Dallas introduced the first “pre-print” wax glassine bags, called “Dixie's Fresheen.” Nonbleeding ink was used to print on one side of the paper. The National Potato Chip Institute (NPCI) was founded in 1937. The first challenge of the NPCI was to educate both retailers and the consumers about potato chips and their uses. Some retailers believed that potato chips were similar to soap chips and were to be used on washday. Other retailers suggested to the consumers that they should place the chips in a bowl, and add sugar and cream to the chips. In 1959, the National Potato Chip Institute (NPCI) changed its name to Potato Chip Institute International (PCII), to reflect the worldwide membership. Later in 1976, there was yet another name change to Potato Chip/Snack Food Association (PC/SFA) to reflect the existence of snack foods other than potato chips. The headquarters of the PC/SFA also was moved from Cleveland to the Washington, DC area. In 1986, the PC/SFA again changed its name. It celebrated its Golden Anniversary with the new name Snack Food Association (SFA). Today’s leader, Frito-Lay of Texas, has brought about the most dramatic evolution in the American snack food industry. It all started in 1932, with two individuals who were producing two entirely different products in two separate parts of the country. Mr. Elmer Doolin of San Antonio started the Fritos brand corn chips. The Frito company expanded and moved its headquarters to Dallas in 1933. Mr. Doolin came across a corn product that had a very unique flavor and texture. He sought out the company owner and purchased the company with all the rights to the secret process, formula, and the process equipment in 1938. The kitchen of Mr. Doolin’s mother was the first manufacturing plant for the Fritos brand corn chips. Elsewhere, Mr. Herman W. Lay started to sell potato chips to the stores in Nashville TN, the same year that Mr. Doolin started to sell his product in San Antonio. Mr. Lay was delivering his potato chips to the stores using his 1929 Model A Ford truck. By 1934, his company had established six delivery routes. In 1938, through reorganization the company’s name was changed to H.W. Lay & Company. The company started to flourish under the new name and organization, selling Lay’s brand Potato Chips.



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The industry suffered from a short supply of raw material and fuel from 1941 to 1945, when United States was engaged in the Second World War. Business expansion and development were essentially halted during those years because of food and fuel rationing. In 1945, the Frito Company granted a license to the H.W. Lay Company to be the first exclusive franchise to manufacture and distribute Fritos corn chips in the Southeast. A close relationship grew between the two companies. In September of 1961, just 29 years after they had begun their ventures, the Frito Company and H.W. Lay Company merged to become the Frito-Lay Company. Mr. Doolin died in 1958. He did not see the merger of the two companies but he saw his Frito Company become a dominant snack food enterprise before his death. In 1965, Frito-Lay and Pepsi-Cola merged. Today, Frito-Lay is the leading snack food–producing company in the world. The company sells numerous salty snack food products including include potato chips, corn chips, extruded products, nuts, and a variety of other products. Salty snack foods in the United States have gone through significant changes during the past two decades. In the 1980s, the presence of high saturated fatty acids in animal fats was linked to coronary heart disease. This finding caused the removal not only of animal fats but also palm oil, palm olein, and coconut oil from U.S. snack foods. Palm oil, palmolein, and coconut oils were called “Tropical Oils” and were labeled as “Bad for You Oils.” The name Tropical Oil was later dropped because the FDA disallowed this form of labeling. Unfortunately, palm oil, palm olein, and coconut oils were replaced with hydrogenated soybean oil. No questions were raised about the increased saturated fatty acids in hydrogenated soybean oil. In the late 1980s and early 1990s, there was a heavy promotion of “Low-Fat” and “Fat-Free” salty snack foods. Some low-fat baked products were also introduced with partial or total replacement of fat using fat-replacers available in the market. The idea was to reduce the “fat calories” in the snack food. However, most of these products exhibited poor consumer acceptance after the initial trial period was over. In reality, the U.S. Surgeon General’s report indicated that introduction of these products did not help the general public lose weight. There are probably many reasons for the discrepancy between the low calories per serving and lack of weight loss (or even weight gain) by the users of these low-fat and fat-free products. Probably the most significant development in the fat-free salty snack food area was the introduction of Olestra, better known as Olean by its inventor, Procter & Gamble Company of Cincinnati, OH. Olestra is a sucrose polyester, in which the fatty acids can be derived from soybean, cottonseed, or other vegetable oils. Olestra is indigestible. It can fry snack food like regular vegetable oils, which is what made Olestra very attractive to the snack food manufacturers. The FDA approved Olestra for making salty snack food in 1996. Frito-Lay introduced potato chips and tortilla chips fried in Olestra in the late 1990s and marketed the products under the brand name “WOW.” The brand expansion was quite promising but it never reached the level of prominence in the snack food arena



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because of some complaints from consumers of gastrointestinal discomfort and diarrhea. Also, there were negative reports from the consumer advocates on Olestra. Fried salty snack foods are considered to be an indulgence food and are consumed for pleasure. Most of the low-fat and no-fat products are lacking in flavor, texture, and mouth-feel attributes compared with products fried in oils. Consumers began to move away from the low-fat and no-fat products after having consumed them for a period of time. It seems that the majority of the salty snack food users still prefer the taste of the full-fat products. United Kingdom. Potato chips are one of the most popular and oldest savory snacks sold in the UK. It is believed that Sir Walter Raleigh and Sir Francis Drake brought potatoes to England from Peru in 1570. Soon the crop expanded into various parts of Europe, and by the end of the 18th century, potatoes were available almost everywhere on the European continent. A man named Frank Smith started his potato chip plant and sold the product in the early 1900s. The chips were sold in bags made of grease-proof paper. Germany. Frank Flessner and his wife Ella started their Stateside Potato Chip Company in Germany in 1951. The chips were made at home, packaged in glassine bags, and delivered to the U.S. Army base in Germany. U.S. soldiers were his primary clients. By 1961, the company had established two manufacturing plants. Flessner convened a meeting in Frankfurt, Germany among Flessner, Harvey Noss (USA), David Sword (UK), and John Zweifel (Switzerland). This marked the beginning of semiannual meetings whose participants would eventually form the European Snack Food Association (ESA). Both ASA and ESA provide numerous valuable services to the members of the respective Associations including information on legislative, economic, technical, and political issues related to the snack food industry. Other Cultures and Regions. The history of the snack-food industry or of its products is difficult to obtain in other countries because of the lack of documented information. For example, Indians consume at least 300 different varieties of salty snacks that are fried in vegetable oils. These products contain grains, pounded rice, nuts, vegetables, raisins, legumes, coconut, and seasoning to suit the palates of the people in the various parts of the country. Although these products have been used for centuries, no one can determine the date or the place of origin of most of these products. This market has advanced from a cottage industry to the manufacturing sector in the past three decades. A large number of these products are exported to the United Kingdom, the United States, Canada, and many European countries. The salty snack food industry is now entering into the area of “Natural” and to some degree “Organic” products that are being fried in nonhydrogenated vegetable oils. This sector is expected to grow rapidly. However, the limiting factors are availability and cost of the ingredients. This situation is not expected to improve in the near future, although the demand for this category of product has already increased.



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Major Categories of Salty Snack Foods in the United States Potato chips, the number one salty snack food in the United States, are celebrating their 150th year. The growth, flavor categories, and presentation of the product have gone through several revolutionary changes. The process has evolved from the kitchen fryer to the most modern automated continuous fryers. The packaging has changed from paper sack to glassine paper bags to the metallized film packaging with nitrogen flush for better shelf life. In 2001, potato chips sales in the United States were estimated at 1.848 billion pounds, with approximate sales of $6.039 billion. Tortilla chips were the next biggest sellers, with ~1.5 billion pounds and an estimated revenue of $4.1 billion in the United States in 2001. Table 1.1 lists the predominant salty snack foods sold in the United States in 2001 and 2000. Sales of potato chips, the number one salty snack food product in the United States, have grown at an annual rate of 3–4%. The product is sold in the country through various channels as listed in Table 1.2. Table 1.3 lists the top 20 brands of potato chips in the United States and their sales figures for the year 2001. The fatfree category showed a significant decline in sales in 2001 compared with previous years. This decline occurred in part because of reduced interest in the niche market as well as the negative reports on Olestra by various consumer advocates. TABLE 1.1 Year 2001 and 2000 Salty Snack Food Sales in the United Statesa,b Segment Potato chips 2001 2000 Tortilla/Tostada chips 2001 2000 Corn snacks 2001 2000 Pretzels 2001 2000 Snack nuts 2001 2000 Microwave popcorn 2001 2000 Ready-to-eat popcorn 2001 2000

Sales (million $)

Change (%)

Volume (million lbs)

Change (%)

6039.2 4955.3

+7.0 +5.7

1848.6 1610.8

+3.0 +4.7

4148.2 3950.7

+5.0 +5.4

1501.9 1483.2

+1.3 +3.6

933.7 914.5

+2.1 +7.9

279.1 280.0

–0.3 +2.8

1204.1 1193.4

+0.9 –2.2

580.1 586.3

–1.1 +3.1

1839.6 1812.4

+1.5 +7.7

515.9 503.9

+2.3 +4.2

1273.3 1245.9

+2.2 +7.7

453.9 448.1

+1.3 +5.5

466.9 490.4

–4.8 –0.5

124.5 130.9

–5.1 –0.5 Continued



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TABLE 1.1 (Cont.) Segment Unpopped popcorn 2001 2000 Cheese snacks 2001 2000 Pumpkin/Sunflower seeds 2001 2000 Meat snacks 2001 2000 Pork rind 2001 2000 Variety pack 2001 2000 Others 2001 2000 Total 2001 2000

Sales (million $)

Change (%)

Volume (million lbs)

Change (%)

78.1 80.3

–2.8 +0.6

87.1 90.6

–3.9 –1.4

1027.1 990.4

+3.7 +7.7

332.6 324.2

+2.5 +4.4

138.3 131.1

+5.5 +15.7

52.4 51.2

+2.4 +11.7

2011.2 1739.8

+15.6 +31.7

139.5 121.4

+14.9 +26.2

498.5 511.8

–2.6 +21.8

83.7 83.1

+0.7 +24.9

345.9 347.6

–2.6 +3.1

76.6 86.8

–11.8 +4.9

1794.2 2325,6

+3.5 –0.4

392.4 597.5

–1.6 –0.8

21,798.3 20,689.2

+3.5 +6.4

6468.3 6398.0

+1.4 +3.6

aSource:

Reference 3, p-SI-5. to the Snack Food Association, the consumption of snack food in the United States, based on a population number of 272 million, for the year 2000 was as follows: The U.S. consumed 1680 potato chips per person. The number of potato chips consumed in the U.S. was 451,024,000,000 (451 billion). The number of pounds of snack foods consumed per person was 23 lbs. Meat snacks posted the highest increase in sales with a >30% gain. The total snack sales worldwide were an estimated $55 billion (U.S. Commerce Department). According to the U.S. AgExporter (4), U.S. exports of savory snacks were $1.6 billion. bAccording

Tortilla chips are the second largest category of salty snack food sold in the United States as shown in Table 1.1. In 2001, the sales of tortilla chips in the country was $4.148 billion, with an average growth of 5%. Like potato chips, tortilla chips are also sold in the United States through various channels as listed in Table 1.4. Table 1.5 lists the top 20 brands of tortilla chips in the United States. As with potato chips, fat-free tortilla chips showed a significant loss in sales volume. The snack food business has grown from a $13.8 billion industry in 1992 to $21.8 billion in 2001. Table 1.6 lists snack food sales chronologically for the past decade. The volume growth for the snack food industry has been 3–4%, with a few



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TABLE 1.2 Sales Channels for Potato Chips in the United Statesa Product sold (%)

Location Supermarket Grocery stores Mass merchandiser Warehouse club Drug store Convenience Store Vending machine Food service Other aSource:

43.1 10.0 8.1 2.5 2.6 15.6 5.0 4.7 8.3

Reference 3, p-SI-49.

exceptionally high and low growth years. The revenue increase has been steady except in 1995, when the snack food market lost both volume and net dollar sales. The general economy and the cost of ingredients were believed to be responsible for the low sales volume. TABLE 1.3 Top 20 Brands of Potato Chips in the United States During 2001a Rank

Brand

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Lay’s Ruffles Wavy Lay's Pringles Private label Utz Wise Ruffles Flavor Rush Lay’s Bistro Gourmet Ruffles WOW Pringles Right Crisps Herr Jay’s Cape Cod Lay’s WOW Old Dutch Golden Flake Pringles Fat Free Pringles Cheesums Mike-Sells

aSource:

Volume (million $)

Change (%)

$ Share (%)

Volume (million lb)

Change (%)

834.2 334.6 290.3 224.4 149.8 68.0 59.4 56.6 51.0 50.2 49.1 47.5 43.1 42.8 41.5 37.1 27.9 27.0 20.2 19.8

+2.2 +1.0 +54.3 +7.4 +3.7 +8.5 –1.5 –18.6 N/A –5.8 –13.8 +10.0 +3.7 +13.3 –10.6 +10.9 +1.6 –14.5 +7.6 –0.9

29.9 12.0 10.4 8.0 5.4 2.4 2.1 2.0 1.8 1.8 1.8 1.7 1.5 1.5 1.5 1.3 1.0 1.0 0.7 0.7

266.3 92.5 91.9 67.5 68.0 21.8 19.9 14.5 11.4 8.5 13.4 15.9 14.3 8.5 6.9 13.1 9.0 5.5 5.9 6.5

–1.4 –4.1 +48.9 +1.6 +2.9 +5.3 –1.7 –16.7 N/A –19.6 –20.2 +1.0 +5.3 +12.7 –23.4 +8.9 +2.3 –15.1 +4.1 –2.5




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TABLE 1.4 Sales Channels for Tortilla Chips in the United Statesa Product sold (%)

Location Supermarket Grocery stores Mass merchandiser Warehouse club Drug store Convenience Store Vending machine Food service Other aSource:

40.1 12.8 7.5 3.9 1.9 13.5 5.8 4.7 9.8


Other Categories of Snack Foods In addition to chips, popcorn and nuts, there are many different fried snack foods sold in almost every country. Some of these are made from extruded dough, whereas others are made from pellets. The products are generally fried at ≥190°C. TABLE 1.5 Top 20 Brands of Tortilla Chips in the United States During 2001a Rank Brand 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Doritos Tostitos Private Label Santitas Mission Baked Tostitos Tostitos Scoops Doritos Extremes Tostitos WOW Doritos WOW Old Dutch Tostitos Santa Fe Gold Pardinos Herr Snyder's of Hanover Garden of Eatin Blue Chips Utz Daines Guiltless Gourmet Chi Chi Fiesta

aSource:



Volume (million $)

Change (%)

$ Share (%)

Volume (million lb)

Change (%)

709.9 594.5 85.7 68.7 47.9 40.3 36.6 29.3 24.1 19.6 15.7 12.3 11.7 9.7 9.3 8.8 8.3 7.4 7.0 6.6

+4.7 –2.7 +4.5 +7.3 +3.6 –19.9 N/A N/A 9.6 10.0 +4.0 +2172.0 38.5 +6.7 +4.5 +43.5 +9.4 3.7 +2.6 +7.0

37.6 31.5 4.5 3.6 2.5 2.1 1.9 1.5 1.3 1.0 0.8 0.6 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.3

220.5 175.1 45.6 39.7 27.3 9.8 9.2 8.6 4.3 3.3 6.4 3.5 4.5 3.8 4.7 2.0 3.4 3.4 1.3 2.8

+2.7 –7.1 +1.8 +8.7 –1.6 28.7 N/A N/A 20.8 21.3 +3.0 +2204.5 42.9 +3.9 5.2 +45.1 +4.6 12.0 0.2 +1.2


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TABLE 1.6 Snack Food Sales from 1992 to 2001a

aSource:

Year

Sales (billion $)

Growth (%)

Volume (billion lbs)

Growth (%)

2001 2000 1999 1998 1997 1996 1995 1994 1993 1992

21.80 20.69 19.38 18.17 16.84 15.41 15.09 15.05 14.66 13.80

+5.1 +6.3 +6.2 +7.3 +8.5 +2.1 +0.3 +2.6 +5.9 +2.7

6.47 6.38 6.17 5.90 5.77 5.61 5.54 5.69 5.52 5.18

+3.3 +3.3 +4.4 +2.2 +2.8 +1.3 –2.7 +3.0 +6.2 +5.0


The fried products are dusted with seasonings and packaged. This is one of the growing segments in the snack food area. Types of Oil Used in Making Salty Snack Foods It is interesting to note that the oils used in making salty snack foods follow the “rule of availability and cost.” For example, in the United States, potato chips were fried in liquid cottonseed oil from the beginning. Other oils such as peanut and corn, were also used. The potato chips fried in cottonseed oil became the Gold Standard for potato chips in the United States because of the taste of the product and the availability of the oil in the country. However, as the supply of cottonseed oil began to fall in recent years and that of corn oil began to rise at a moderate price increase, the snack food industry switched over to corn oil. Sesame seed oil and sunflower oils have been traditionally used more commonly in Mexico to fry snack foods because the consumers like the taste of the products fried in these oils. However, the supply of partially hydrogenated soybean oil and palmolein at reduced cost prompted many snack food processors to switch over to these oils. People in India and China like food fried in peanut oil. Here the people have started to use palmolein, palm oil, and other less costly oils to remain profitable in the business. In many African and South American countries, almost any indigenous oil is used for frying. Malaysians use palm and palmolein for frying. The Philippinos and South Indians have used coconut oil for frying and cooking foods for centuries, simply because these oils have been available in the region. In today’s snack food industry, the frying oil is chosen on the basis of the following criteria: (i) product flavor; (ii) texture; (iii) mouth-feel; (iv) aftertaste; (v) product shelf life; (vi) availability; (vii) cost; and (viii) nutritional requirements. The snack food companies in the advanced countries use the first four criteria listed above to determine the acceptability of any oil for a given product. Items (v)–



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(vii) are related to the company’s profitability. The last item is becoming more important in affluent countries in which consumers are able to pay the high price for the product fried in the so-called “healthful oils” that are low in saturated fats and are not hydrogenated. The prime examples are high oleic sunflower, high oleic canola, midoleic canola, mid-oleic sunflower (NuSun), and low-linolenic canola oils. For the most part, even in countries such as the United States, the cost and availability of oil are very critical for the sustenance of a snack food manufacturer. The reason is that there is a huge price gap between the more abundant oils such as palmolein or soybean compared with high-oleic sunflower, NuSun (mid-oleic sunflower), or high oleic safflower oils. Soybeans, the largest source of vegetable oil in the world, are grown predominantly in the United States, Argentina, and Brazil. Some other countries, such as India and China, also produce soybeans. Palm oil is the second largest source of vegetable oil in the world. Worldwide, palm oil production is growing at a much faster rate than is soybean oil. Malaysia and Indonesia are the principal growers of palm oil. Palm oil is also produced in Central America, South America, Africa, and India. Canola (low erucic acid rapeseed), the third largest oilseed crop in the world, grows mainly in Canada and Europe. In addition to soybeans, China and India also produce mentionable quantities of low erucic acid rapeseeds. Sunflower is the fourth largest oilseed crop growing primarily in the former Soviet Union, the United States, Argentina, Canada, and Europe. Other countries such as South Africa and India also produce sunflower seeds for crushing. Table 1.7 lists the latest world oilseed and oil production figures (2). Palmolein is used for frying salty snack food in almost every country except the United States. Cottonseed, corn, partially hydrogenated soybean, canola and sunflower oils are used in the United States for frying. In addition, small amounts of liquid canola, high-oleic sunflower and high-oleic safflower and NuSun oils are also used for frying snack foods in the U.S. A review of the data in Table 1.7 shows that soybean oil is the world leader in volume, followed by palm oil. However, in the salty snack food area, palmolein and palm oil are used in more countries than soybean oil. Soybean oil is used heavily in baked foods. Cottonseed, sunflower, and peanut oils are produced in much smaller volumes and are generally consumed locally by the producing countries. Evolution of the Frying Industry into Diverse Products The frying industry has evolved significantly from the early days of chips. The fryers have become larger and more sophisticated in terms of product-feed, internal construction, oil temperature control, and distribution. Efforts have been made to reduce the volume of oil in the frying system to reduce the oil turnover time, thus preserving the quality of the oil. Batch fryers have been traditionally used to produce smaller volumes and harder texture in the fried chips. New continuous fryers have successfully duplicated the harder texture of the kettle-fried chips, but at a much higher production rate.



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TABLE 1.7 World Production Figures of the Major Oilseeds and Oilsa Seeds produced 2001/02

Seeds produced 2000/01

184.21 — 37.47 23.11 36.43 — 24.11 —

175.20 — 37.14 24.41 37.27 — 22.94 —

Type of oil Soybean Palm Canola Sunflower Cottonseed Corn Peanut (groundnut) Coconut aSource:

Oils produced 2001/02

Oils produced 2000/01

(million metric tons) 29.37 24.73 13.51 7.38 4.27 1.11 5.46 3.19

27.05 23.83 13.95 8.67 3.94 1.09 4.87 3.51

Reference 2.

Continuous fryers with a very specialized design of the frying bed have been introduced to fry preformed chips with a very low oil turnover time. Normally, these products require a very short fry time. Par-fried products, such as French fries, potato nuggets, chicken, or chicken fried steaks, are all par-fried products that are frozen immediately after frying and stored at –5 to –10°F. The product is distributed in freezer trucks. These products are fried directly from “Freezer to Fryer” without any thawing and served immediately in restaurants, through food services, and even at home. These products have the great advantage of convenience and reduced cost. Products, such as par-fried French fries, chicken, and coated vegetables require shortening with a fairly high level of solids, which can be achieved through the standard hydrogenation process as it is done in the United States and several other countries. Batter-coated fish fillets are fried in either lightly hydrogenated oil or nonhydrogenated oil. The storage temperature of –5 to –10°F helps protect the oil from rapid oxidation. This allows the food processors to use nonhydrogenated oils. Three countries, the United States, Canada, and the Netherlands, are the major producers and exporters of frozen French fries. According to the Department of Commerce, the U.S. Census Bureau, Foreign Trade Statistics, the United States exported nearly $316 million worth of frozen French fries in 2002. The export statistics on frozen French fries for the past 6 years are listed in Table 1.8. Other parfried frozen products include fish sticks, breaded shrimp, and par fried chicken as mentioned above. Table 1.9 lists the production and sales figures of fish sticks and breaded shrimp from 1992 to 2001. An alternative shortening for French fries or heavy-duty industrial frying can be made via fractionation of palm oil and/or the interesterification process. This approach has been applied successfully in several countries outside of North America. These shortenings have higher amounts of palmitic and stearic acids than



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TABLE 1.8 French Fries Production Data for the United States (1997–2001) Year Volume (million lbs)

1997

1998

1999

2000

2001

13,162.8

14,293.2

14,019

14,686

12,671

the conventional hydrogenated shortening. However, if the trans fatty acids are considered as fatty acids that behave like saturated fatty acids, the interesterified product contains a significantly lower amount of cholesterol-promoting fatty acids (combined saturated and trans fatty acids). At present, these products are more expensive than the conventionally hydrogenated shortening. Possibly the concern over trans fatty acid might encourage the oil processing industry to look into a more economical way to produce interesterified shortening in the near future. Pourable shortening, made from fully hydrogenated soybean (or canola) oil and lightly hydrogenated soybean or canola oil can provide the functionality of the heavy-duty frying shortening with a significantly lower trans fatty acid content. The trans fatty acid content of the pourable shortening can be reduced practically to zero by replacing partially hydrogenated soybean or canola oil with liquid oils, such as high-oleic sunflower, canola, safflower, or NuSun, corn or cottonseed, which are low in linolenic acid. This, of course, is a costlier proposition. Comments on the Par-Frying Process Although par-frying is a very attractive means for large-scale product distribution, this method will not produce a shelf-stable product if one attempts to par-fry the salty snack product and distribute it to the large-scale snack food manufacturers, who in turn pull the product from the freezer, fry it, package, and distribute it. The product will develop a rancid flavor very rapidly. This is because the product in the par-frying process absorbs less oil than in the full-frying process. This increases the oil turnover time in the fryer, causing more damage to the oil and forms a higher concentration of free radicals in the oil. These free radicals are carried by the product and further catalyze the oxidative degradation of the oil in the product during storage. TABLE 1.9 Fish Sticks and Breaded Shrimp Production Data for the United States (1997–2001) Fish sticks

Breaded shrimp

Year

(million lbs)

(million $)

(million lbs)

(million $)

1997 1998 1999 2000 2001

31.37 31.19 29.49 18.11 19.51

64.30 63.47 63.40 42.55 41.53

117.47 109.48 119.15 121.40 152.19

334.94 333.26 351.89 375.45 539.63



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There is always an exchange of oil between the food product and the frying oil. A high concentration of free radicals in the fryer feed will result in higher concentration of free radicals in the final fryer. This will accelerate the autoxidation process in the frying oil and reduce the shelf life of the re-fried product even when it is packaged in nitrogen flushed and metallized bags. The product will have a fraction of the shelf life of the same product fried under normal processes (not parfried and refried). Miscellaneous Fried Snacks Donuts. Freshly fried donuts are very popular and used for breakfast or snack. These products are yeast-raised and fried in hydrogenated shortening to provide the taste. Interesterified shortening or that made from fractionated palm oil components can be used to fry donuts. Shelf-stable donuts are sold in the supermarkets, convenience stores, or gas stations. These products are generally baked, instead of fried for longer shelf life. Fried Nuts. Peanuts, cashews, sunflower seeds, and pumpkin seeds are sold in various forms, such as fried, dry roasted, coated, and glazed. In frying nuts, there is very little oil pick up by the product. This greatly increases the oil turnover time in a fryer. It will be clear from the discussions in the later chapters in this book that the type of oil used in this process must have good oxidative stability to obtain good shelf life for the product. Some manufacturers use nonhydrogenated canola oil in this process. The high-linolenic acid in liquid canola oil does not provide good shelf life for the product. The liquid oil used in this process must have a low linolenic acid content, e.g., cottonseed, corn, high-oleic sunflower, NuSun, low-linolenic canola, or high-oleic canola. Otherwise, one must use lightly hydrogenated canola or soybean oil to achieve good shelf life. Stuffed vegetables, breaded vegetables, breaded shrimp, for example, are fried at the restaurants and served immediately. These products are generally fried in liquid oils or in pourable shortening. Snack Food Market in Europe As mentioned earlier, the snack food industry is quite large and extensive in Europe. It is more difficult, however, to obtain comprehensive data on all types of snack foods in European countries compared with the United States. The overall tonnage of potato chips and other snack foods and snack nuts are shown in Table 1.10. In comparison with the United States, per capita consumption of snack food in the European Union is much lower.

Summary The frying industry includes restaurant as well as restaurant operations. Restaurants fry fresh foods or use a wide variety of par-fried products such as French fries, potato wedges, stuffed cheese sticks, potato skins, vegetable/cheese stuffing, or batter-coated


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vegetables. These products are fried and served immediately. The frozen par-fried products are fried at the restaurants without thawing. This helps the product to retain good oil flavor as well as a crunchy crust. Packaged salty snack food products require a long shelf life after frying and packaging. This makes it essential to use an oil that has good oxidative and flavor stability. Par-fried foods use oils ranging from liquid [refined, bleached, deodorized (RBD)] oil to heavily hydrogenated shortening. Shelf-stable snack foods must use oils such as RBD oils with low or no linolenic acid, lightly hydrogenated soybean, or canola oil with a linolenic acid content of 150°C, and the reaction equilibrium is shifted in favor of other hydrolysis products. The extent of hydrolysis is a function of various factors such as oil temperature, interface area between the oil and the aqueous phases, and amount of water and steam, because water will hydrolyze oil more quickly than steam. FFA and low-molecular-weight acidic products produced from oil oxidation enhance hydrolysis in the presence of steam during frying. Degradation products from hydrolysis decrease the fry life of the oil. The level of the FFA is a measure of the degree of hydrolysis in the oil.


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Fig. 2.2. Hydrolysis

process for frying oils.

Oxidation. Oxygen is present in fresh oil and more is added to the frying oil when food is placed in the fryer. Heat, along with the addition of food, produces a series of reactions including the formation of free radicals, hydroperoxides, and conjugated dienoic acids. The chemical reactions that occur during the oxidation process help to form both volatile and nonvolatile decomposition products. For example, ethyl linoleate oxidation leads to the formation of conjugated hydroperoxides, which can form noncycling long-chain products or they can cyclize and form peroxide polymers. The oxidation mechanism in frying oils is similar to autoxidation at room temperature; however, the unstable primary oxidation products (hydroperoxides) decompose rapidly at frying temperatures into secondary oxidation products, such as aldehydes and ketones (Fig. 2.3). Secondary oxidation products that are volatile contribute significantly to the odor of the oil and flavor of the fried food. For example, unsaturated aldehydes, such as 2,4-decadienal, 2,4-nonadienal, 2,4-octadienal, 2-heptenal, or 2-octenal, contribute to the desirable, characteristic deep-fried flavor in oils during the second phase of the frying cycle. However, saturated and unsaturated aldehydes such as hexanal, heptanal, octanal, nonanal, and 2-decenal, produce distinctive off-odors in the frying oil. The fruity and plastic offodors typical of heated high-oleic oils can be attributed primarily to heptanal, octanal, nonanal, and 2-decenal. In deteriorated frying oil, acrolein is primarily responsible for the typical acrid odor. Analysis of primary oxidation products, such as hydroperoxides, at any one point in the frying process provides little information because their formation and decomposition fluctuate rapidly and are not easily predicted. During frying, oils with polyunsaturated fatty acids (PUFA), such as



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Fig. 2.3. Oxidation

process for frying oils.

linoleic acid, have a distinct induction period of hydroperoxide formation followed by a rapid increase in peroxide values, then a rapid destruction of peroxides. Measuring levels of PUFA, such as linoleic acid, can help determine the extent of thermal oxidation. Oxidative degradation will produce oxidized triacylglycerols containing hydroperoxide-, epoxy-, hydroxy-, and keto-groups and dimeric fatty acids or dimeric triacylglycerols. Volatile degradation products can be saturated and monounsaturated hydroxy-, aldehydic-, keto-, and dicarboxylic-acids, hydrocarbons, alcohols, aldehydes, ketones, and aromatic compounds. Polymerization. Polymerization results in the formation of compounds with high molecular weight and polarity (Fig. 2.4). Polymers can form from free radicals or triacylglycerols by the Diels-Alder reaction. Cyclic fatty acids can form within one fatty acid; dimeric fatty acids can form between two fatty acids, either within or between triglycerides; and polymers with high molecular weight are obtained as these molecules continue to cross-link. As polymerized products increase in the frying oil, the viscosity of the oil also increases. Causes of Oil Deterioration Degradation of frying oil is affected by many factors, such as unsaturation of fatty acids, oil temperature, oxygen absorption, metals in the food and in the oil, and type of food (Table 2.1). The type of food being fried alters the composition of the frying oil because fatty acids are released from fat-containing foods, such as meat and fish, and their concentration in the frying oil increases with continued use. Breaded and battered food can degrade frying oil more quickly than nonbreaded



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Fig. 2.4. Polymerization process for frying oils.

food. For example, onion rings are more detrimental to the oil than potato chips, possibly because of the breading material that accumulates in the oil. However, even foods such as potatoes degrade oil stability because of the increased addition of oxygen as the food is added to the frying oil. Food particles accumulating in the oil also deteriorate oil quickly; therefore, filtering oils will help remove these particles along with other oxidation products and can help to extend oil fry life. Frying protocols of intermittent or continuous frying affect fry life. For example, cottonseed oil heated intermittently had as much polar material as oil heated continuously for three times as long. This difference may be caused by the TABLE 2.1 Factors Affecting Frying Oil and Fried Food Degradation Oil/food • Balance amount of unsaturated and saturated fatty acids for optimal oil fry life, healthfulness, flavor quality, and stability of fried food • Choose oils with moderate-to-high stability • Consider nature of food: nonbreaded/battered foods degrade oils less than do breaded/ battered foods • Chelate metals in oil with use of metal chelator, such as citric acid • Use oils with good initial quality • Do not allow degradation products to accumulate in oil • Use antioxidants and antifoam additives Process • Keep oil temperature neither too high nor too low • Avoid prolonged frying time • Minimize aeration/oxygen absorption • Keep frying equipment in good condition • Maintain continuous frying, which is better than intermittent frying • Add makeup oil to ensure good oil turnover rate • Filter oil and clean fryer



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increased amounts of fatty acyl peroxides that decompose upon repeated heating and cooling, causing further oil damage. Replenishing the fryer with fresh oil is commonly done in most frying operations; however, in the snack food industry in which more make-up oil is added than in restaurant-style frying, a complete turnover time of 8–12 h can be achieved in a continuous fryer. Levels of the reaction products in frying oil can also be affected by absorption into the fried food. Evaporation of aldehydes and ketones takes place, but fatty acids are not distilled under frying conditions. Some amount could be removed from the fryer as entrainment in the water vapor leaving the fryer and being removed through the exhaust duct. However, the accumulation of degradation products in the frying oil and their eventual absorption in fried foods is of primary concern when commercial frying is done under abusive conditions. In summary, the following characteristics of the oil and/or food affect the amount of oil deterioration during frying: type of food, type of oil, unsaturation/saturation of fatty acids, metals in food or oil, initial oil quality, degradation products in the oil and additives to the oils, such as antioxidants and antifoam agents. The following frying procedures also affect oil deterioration: frying time and rate, oxygen, fryer type, surface-to-volume ratio of the oil, oil temperature, continuous or intermittent frying, addition of makeup oil, and filtering of oil. Products from Oil Deterioration In deep fat frying, both thermal and oxidative decomposition of the oil occur, producing volatile and nonvolatile decomposition products. These two types of compounds are of interest because the volatile compounds affect the flavor of the food and the room odor of the frying oil, whereas the nonvolatile compounds affect how long the oil can be used for frying and how long the fried food can be stored before it is consumed. Not only do these compounds adversely affect the stability of the frying oil as already discussed, but the foods fried in deteriorated oils may also contain a significant amount of decomposition products that have potentially adverse effects on the food safety, flavor, and flavor stability of the fried food. The volatile compounds are responsible primarily for flavor (both positive and negative) in the fried food. Undesirable off-flavors can be produced if frying oil is allowed to deteriorate. Nonvolatile compounds, such as polymers, at low levels, may not have much effect on the flavor of a food that is consumed immediately after frying; however, they do affect the fry life of the oil and the shelf life of aged fried food. Thermal polymers may exist in an edible product, but the conditions for their formation are not usually encountered in commercial practice because snack food frying processes are found to be less drastic when good operating protocols are followed. Effects of Volatile Compounds on Flavor of Fried Food When oils are heated to frying temperatures, many compounds are produced as the fatty acids decompose. For example, when pure linoleic acid, a major fatty acid in



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most vegetable oils, is heated, the primary volatile compounds include pentane, acrolein, pentanal, 1-pentanal, hexanal, 2- and/or 3-hexanal, 2-heptenal, 2-octenal, 2,4-nonadienal, 2,4-octadienal, and 2,4-decadienal. All of these compounds produce characteristic odors and flavors that affect the room odor of the frying oil and the flavor of the fried food. The 2,4-decadienal is the major contributor to deepfried flavor, but 2-heptenal, 2-octenal, 2,4-nonadienal, 2,4-nonadienal, and 2,4octadienal also are described as producing a deep-fried odor. Some compounds listed above will usually produce off-odors. For example, an acrid odor is a result of acrolein, and grassy odor is produced by hexanal and 2- and/or 3-hexanal. Frying oils such as high-oleic sunflower have undesirable fruity and plastic odors because of the volatile compounds that decompose from oleic acid. Heptane, octane, heptanal, octanal, nonanal, 2-decenal, and 2-undecenal can be found in most oils because they arise from the oxidation of the oleic acid. But when oleic acid is a major component of the oil, such as in high-oleic (>80%) oils, the off-flavor and odors such as plastic/waxy and fruity are noticeable. Fruity flavors are produced from octanal and nonanal, and plastic/waxy from 2-decenal and 2-undecenal. This information helps explain the origin of the deep-fried flavor that is characteristic of high-linoleic frying oils, but that is present only at low levels in higholeic oils. In addition, the types of chemical compounds derived from oleic acid help explain why high-oleic oils have plastic, waxy and fruity odors that are hardly noticeable in oils with low levels of oleic acid. Effects of Nonvolatile Compounds on Fry Life of Oil Nonvolatile products in deteriorated frying oils include polymeric triacylglycerols, oxidized triacylglycerol derivatives, and cyclic compounds. Polymeric triacylglycerols result from condensation of two or more triacylglycerol molecules to form polar and nonpolar high-molecular-weight compounds. The nonpolymerized part of the oil contains mainly unchanged triacylglycerols in combination with their oxidized derivatives. In addition, it contains monoacylglycerols and diacylglycerols, partial glycerides containing chain scission products, triacylglycerols with cyclic and/or dimeric fatty acids, and any other nonvolatile products. However, much oil deterioration is required for a significant amount of these polymers to form. In continuous potato chip processing, this is not usually a problem because frying conditions are monitored carefully and a high oil turnover rate is achieved. However, oil used in industrial batch fryers (kettle fryers) or small-scale batch frying operations, such as restaurants, is found to deteriorate more because of high oil turnover time. Measuring Deterioration Products The physical and chemical changes occurring in frying oils and the many compounds formed in deteriorated frying oil have been reported extensively. Although these compounds often are used to measure degradation, many of the existing



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methods are based on measuring nonspecific compounds that may or may not relate to oil degradation or fried food quality. Therefore, it is not surprising that frying is often described as more of an art than a science. In fact, the frying industry is still searching for the ultimate criteria to rapidly evaluate frying stability of oils and fried food flavor quality and stability. The standard methods used to measure degradation products in frying oils include polar components, conjugated dienes and fatty acids, as well as rapid analyses, such as the dielectric constant (Table 2.2). Four well-known rapid tests include Food Oil Sensor (FOS) (Northern Instruments, Lino Lakes MN), which measures the dielectric constant in frying fat relative to fresh oil; the RAU-Test, which is a colorimetric test-kit that contains redox indicators reacting with the total amount of oxidized compounds; Fritest (E Merck, Darmstadt, Germany), which is a calorimetric test-kit sensitive to carbonyl compounds; and the Spot Test, which assays FFA to indicate hydrolytic degradation and FFA. The Food Oil Sensor correlates better with polar compounds than do the RAU-Test, Fritest, and Spot test. The amounts of FFA are usually not a reliable indication of deteriorated frying fat. Practically, commercial frying oil operators want to know “When should frying oil be discarded?” Because there are many variables that affect oil degradation as discussed previously, a specific method may be useful for one operation, but not for another. Determining the endpoint of a frying oil requires good judgment, knowledge of the particular frying operation, as well as the type of frying oil, appropriate analytical measurements, and the expected shelf life of the fried food. Some of the laboratory methods used to measure degradation products in frying oil include column chromatography and high-performance sizeexclusion chromatography to detect both polar and nonpolar compounds. Several techTABLE 2.2 Methods to Measure Deterioration Products in Frying Oil Nonvolatile compounds and related processes

Method/Reference

Iodine value Fatty acid composition Total polar compounds Free fatty acids Dielectric constant Nonurea adduct–forming esters Fryer oil color Viscosity Smoke point Foam height

AOCS Cd 1–25/93 (1) AOCS Ce 1–6293 (1) AOCS Cd 20–91/97 (1) AOCS Ca 5a-40/93 (1) (Fritsch, 1981) (2) (Firestone, 1961) (3) AOCS Td 3a-64/93 (1) (Stevenson, 1984) (4) AOCS Cc 9a-48/93 (1) (Billek, 1978) (5)

Volatile compounds and related processes

Method/Reference

Peroxide value Conjugated dienes Volatile compounds Sensory analysis of odor and flavor

AOCS Cd 8–53 (1) AOCS Ti 1a-64 (1) AOCS Cg 4–94 (1) (Warner, 1995) (6)



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niques, including direct injection, static headspace, dynamic or purge-and-trap headspace, and solid phase microextraction, all of which use capillary gas chromatography, can analyze volatile compounds. The rapid methods mentioned above, such as the Food Oil Sensor, can be used successfully to estimate frying stability in restaurant-type frying operations. Measuring Deterioration Products Related to Fry Life Nonvolatile decomposition products are a better measure of degradation of frying oil than are volatile products because volatile compounds are constantly forming and decomposing. Nonvolatile higher-molecular-weight compounds are reliable indicators of fat deterioration because their accumulation is steady and they are not volatile. For example, total polar compounds usually increase linearly with increasing frying time and polymers have also been shown to increase with increasing heating time. High statistical correlations have been obtained between number of fryings and amounts of decomposition products in the oil, including total polar compounds, diacylglycerols, triacylglycerol polymers, and triacylglycerol dimers. FFA may not correlate significantly with the number of fryings. Changes from hydrolysis and oxidation parallel each other during frying as indicated by the high correlations between levels of triacylglycerol polymers and triacylglycerol dimers (from oxidation) and diacylglycerols (from hydrolysis) with the number of fryings. Four methods to assess frying oils are commonly used in European laboratories and include gel permeation chromatography (GPC), liquid chromatography (LC) on a silica gel column, polar and nonpolar components column chromatography on silica gel (CC), and petroleum ether–insoluble oxidized fatty acids. Measuring petroleum ether–insoluble oxidized fatty acids is usually time consuming and inaccurate. The GPC method is able to determine dimeric and oligomeric triacylglycerols in frying oil irrespective of the presence of oxidized compounds, whereas the LC method can indicate the total amount of polar and oxidized compounds. Separating polar and nonpolar components by CC is simpler and faster than the other three methods mentioned above. The formation and accumulation of nonvolatile compounds are responsible for physical changes in frying oil, such as increased viscosity, darkening in color, increased foaming, and decreased smoke point as described earlier. Most methods for assessing deterioration of frying oils are often based on these changes. Nonspecific methods for measuring nonvolatile compounds in deteriorated frying oil include FFA, nonurea adduct-forming esters, peroxide value, benzidine value, acid value, ultraviolet absorbance, refractive index, and petroleum ether–insoluble oxidized fatty acids. None of these methods are considered good measures of heat abuse. In Europe, values of 24–27% polar materials are common endpoints for discarding frying oil in restaurant frying. However, if fried foods are to be stored for a period of time before they are consumed, the level of polar materials must be much less than the 24% endpoint, with recommendations of sage extract > BHT > control. The same order was reported in potato chip stability. Rapeseed oil containing rosemary extract and methyl silicone had lower levels of polar compounds and polymers, and French fried potatoes had improved flavor quality (27). The effect of the rosemary extract alone was not measured. Even breading material from cottonseed flour has been shown to inhibit frying oil degradation because the flour contained polyphenolic compounds (28). Protective Properties of Antioxidant Decomposition Products As previously discussed, the breakdown products of antioxidant compounds can have antioxidant properties. Kim and Pratt (29) identified and characterized the decomposition products of TBHQ heated at frying temperatures, including tertiary butylbenzoquinone (TBBQ) as the primary and major oxidation product of TBHQ. They reported that the interconversion between TBHQ and TBBQ played the greatest part in the antioxidant effectiveness and carry-through effect of TBHQ. Silicone (Methyl Silicone, Polydimethylsiloxane) Definition and Uses. A silicone is an organo-silicon polymer with a silicon-oxygen framework (30). The most basic silicone compound, polydimethylsiloxane, is a high-molecular-weight liquid polymer having a very low vapor pressure (0.05% indicates that there might be some trace impurities left in the oil, which can reduce the shelf life of the fried product. Polymers are formed when the oil is heated. The amount of polymers formed during frying depends on: (i) frying temperature; (ii) type of oil; (iii) type and composition of the food being fried; (iv) type of fryer; and (v) operating conditions in a given fryer. The frying process generates two types of polymers, i.e., thermal p o l ymers and oxidative polymers. Thermal polymers are formed when heat is applied to the oil. Oxidative polymers are formed when two or more of the free radicals from the autoxidation reaction react together to form a larger molecule (commonly referred to as the termination step in autoxidation). Thermal polymers can impart a bitter aftertaste to the freshly fried product. Oxidative polymers may not always indicate a problem with flavor in the fresh product, but may cause rapid deterioration of the flavor of the product during storage. The formation of thermal polymers in frying can be avoided through proper fryer operating practices. The presence of trace metals and natural emulsifiers can produce oxidative polymers in the oil during frying; thus, the fresh oil must contain low levels of these components. Table 5.1 lists the recommended analytical standards for fresh frying oil. This list does not include the melting points, solid fat contents or Lovibond colors,



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because these values vary with the type of oil. Table 5.1 indicates that ~96–98% of the oil is comprised of triglycerides (or neutral oil). The rest of the components are nontriglycerides. All vegetable oils contain tocopherols, which are natural antioxidants. The goal of proper oil refining is to retain a high level of these tocopherols in the deodorized oil. The most common tocopherols in vegetable oils are α, β- (small amounts), γ-, and δ-tocopherols. α-Tocopherol provides resistance to photooxidation of the oil; γ- and δ-tocopherols provide autoxidative stability to the oil. Therefore, oils with higher levels of γ- and δ-tocopherols, low linolenic acid, and low levels of trace impurities exhibit higher oxidative stability in the frying process. Table 5.1 indicates that the level of tocopherols must not exceed certain upper limits (shown for soybean oil). A high concentration of tocopherols can cause rapid oxidation of the oil in frying because some of the decomposition products of tocopherols are prooxidants. The PV of the oil must be 0.0 mEq/kg in freshly deodorized oil. A higher value may indicate either a poor vacuum in the deodorizer or improper cooling and storage of the deodorized oil. The PV must be 45%), the batter becomes too thick to be TABLE 9.2 Effect of the Percentage of Solids on Batter Viscosity % Batter solids 25 33.3 40 50 60 66.6 aKerry

Equivalent lb water/ 50 lb dry mixa

Viscosity (cps) at 20°C

Viscosity (cm) at 15 s

150 100 75 50 33.3 25

25 50 103 7720 TTTM TTTM

23+ 23+ 23+ 3.75 TTTM TTTM

Industries starch batter mix #4630; TTTM, too thick to measure.


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handled by the equipment, and at low solid ratios (7) and slows down under acidic pH (12 h, or (ii) not to exceed 70°F for >3 h. The temperature of the hydrated batter is constantly monitored. The batter and the associated product must be destroyed if there is any deviation from the recommended conditions during operation. Refrigeration equipment or ice can be used to manage the temperature condition of the hydrated batter in the process. A temperature recorder is recommended to constantly monitor the temperature of the batter. This can limit the risk of any deviation in the process. Regulatory Considerations for Coated Products The regulation of coated food products is under the auspices of three federal agencies. The manufacture of meat and poultry products is handled by the U.S. Department of Agriculture (USDA) with no fee required for the inspection service. That agency also issues regulations and label approval for all child nutrition (CN) foods that are served as part of the national school lunch program. Coated beef and poultry products are limited to a coating content of 30%. Thereafter, they are required to use the expression “fritter” rather than “patty.” The USDA places its distinctive shield on every processed package. The National Marine Fisheries Service, a subagency of the National Oceanic and Atmospheric Administration (NOAA), is the fee-paid organization that is responsible for on-site seafood inspection at processing plants that desire an optional government shield to be placed on their packages. It has established a detailed listing (Table 9.4) of minimum fishery content percentages for the full range of processed products manufactured under their jurisdiction. This subagency has established “Standards of Identity” for many of the most commonly coated seafood products (58). For instance,



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TABLE 9.4 Minimum Flesh Content Requirements for USDC-Inspected Productsa,b USDC grade mark (%) Fish Raw breaded fillets Precooked breaded fillets Precooked crispy/crunchy fillets Precooked battered fillets Fish portions Raw breaded portions Precooked breaded portions Precooked battered portions Fish sticks Raw breaded sticks Precooked breaded sticks Precooked battered sticks Scallops Raw breaded scallops Precooked breaded scallops Precooked crispy/crunchy scallops Precooked battered scallops Shrimp Lightly breaded shrimpd Raw breaded shrimpd Precooked crispy/crunchy shrimp Precooked battered shrimp Imitation breaded shrimpe Oystersf Raw breaded oysters Precooked breaded oysters Precooked crispy/crunchy oysters Precooked battered oysters Miscellaneous Fish and seafood cakes Extruded and breaded products

c

PUFI mark (%)

— — — —

50 50 50 40

75 65 —

50 50 40

72 60 —

50 50 40

50 50 — —

50 50 50 40

65 50 — — —

65 50 50 40 No minimum; encouraged to put % on label

— — — —

50 50 50 40

— —

35 35

aThis list of minimum flesh requirements for standardized and nonstandardized breaded and battered products is provided to ensure that all users of U.S. Department of Commerce (USDC)-inspected fishery products are aware of the minimum flesh requirements. These requirements apply to all species of battered and breaded fish and shellfish. PUFI, Processed Under Federal Inspection. bNOTE: USDC will certify coated, nongraded products without a standard of identity, etc., such as breaded fish sticks, breaded portions, and similar breaded fish products that contain less than 50% fish flesh if a statement immediately follows as part of the statement of identity declaring the amount of fish flesh actually present; e.g., “Breaded Fish Sticks Containing 45% Fish.” cNo USDC grading standard exists for products without Grade A percentages. dFDA Standard of Identity requires that the product contain 50% shrimp flesh by weight. If a product is labeled “lightly” breaded, it must contain 65% shrimp flesh. eAny product with a Standard of Identity that contains less flesh than the standard requires must be labeled “imitation.” fFlesh content on oyster products can be determined only on an input weight basis during production.



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there is a distinction made between “frozen raw breaded shrimp” that requires at least 50% shrimp content and “frozen raw lightly breaded shrimp,” that stipulates at least 65% shrimp content (59). Breaded shrimp with >50% coating is required to be labeled “imitation” shrimp. The FDA is the agency with regulatory authority over all non-meat or nonpoultry plants, including seafood facilities. Labeling of coated vegetables, cheese, seafood, fruit, or nuts, for example, must comply with that agency’s guidelines, which in some instances may be different from the USDA provisions. Finished Product Sensory Issues The critical sensory factors that influence consumer response to a coated food product are as follows: 1. Crispness—both initially and as the food continues to be masticated. 2. Oiliness—the sensation of warm oil on the palate is a universally enjoyed experience. However, in excess, it causes the food to appear to be “greasy” and undesirable. An excessively low fat level makes the food dry, tough, chewy and unpleasant tasting. 3. Flavor—the trend in coated foods is to enhance the seasoning level, with some markets expecting very intense “Buffalo Wing”-type heat. The salt content of some coated food products can reach high levels; chicken breadings are an example. Variety and balance are important in formulating a winning product. 4. Crust color—plays an important role in the initial visual acceptance or rejection of a coated product. A fried color chart is a useful tool. One coating manufacturer even has placed a color chart on its web site. 5. Heat lamp holding capacity—is the time that the fried food can be kept under the heat lamp and still maintain acceptable flavor. This is particularly important for fast food restaurants and food services that have to keep some product under the heat lamp for ready service to the customers. 6. Durability—is the ability of the coated cooked product to withstand anticipated handling abuse at the cooking site. A cheese stick that blows out its core into the frying oil before it reaches the desired internal temperature is not going to be acceptable to consumers. Similarly, a fish portion that breaks easily when handled with tongs as it is being assembled into a sandwich will result in delayed service and increased cost. In both these examples, corrective measures with the coating system can offer a solution. Common Fryer Problems and Troubleshooting Them Scorched particles are the cause of burnt flavor and sometimes darker product color. This can be corrected. Initially, it is imperative that the source of the problem be minimized; then, proper operating procedures are put in place. Generally,



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the problem originates from a high concentration of loose flour or dusting material on the food surface. Introduction of excessive breading particles into the fryer causes scorching of the released material in the fryer. The situation is generally created by the following factors: (i) using a breading that is too coarse; (ii) improper transfer of products into the fryer; (iii) excess fryer oil turbulence; and (iv) contact with the fryer’s submerger belt, which allows abrasion of the coating. Adequate continuous filtration of the fryer helps remove particles as they are released into the oil. Off-flavors are often associated with a lack of sufficient turnover rate in the fryer, thus allowing breakdown products to build up in the frying oil. If a fryer holds 500 gal of frying oil (~3750 lb) and the fat absorption of the cooked food is 8%, the minimum 7.5-h production rate should be 6250 lb/h to utilize the 500 gal. Less than that rate accelerates oil breakdown and leads to the development of offodors. Another contributor to undesirable flavors is the cross-transfer of flavors from the previous cooking of a high-intensity coated food followed by a much blander food. The frying oil can become the source of flavor carryover. Suitable filtration and treatment with appropriate filtering aids can offer relief for this quality issue. Discarding of the oil is an option. Excessive crust color arises from out-of-control Maillard reactions. One subtle addition is the phenomenon found when the product fries to the proper crust color in the manufacturer’s facility yet is excessively dark at the subsequent restaurant site. This condition can often be traced to partial warming of the frozen product during storage or distribution. Under these conditions, the enzyme system within the coating becomes activated and may combine with proteinaceous fluids from the thawing food core. The enzymes then convert the flour in the coating to sugars, which in turn become available for the Maillard browning reaction. Frost in the packages generally indicates temperature abuse of the frozen product. Excess electrolytes in the coating, depressing the coating’s freezing point, can exacerbate the condition. Batter texture issues and coating blow-off during frying are generally caused by the following: (i) Lack of control of the batter viscosity; (ii) excessive free fatty acid levels (or oil breakdown) in the frying oil; (iii) incorrect product entry from the batter applicator into the hot oil; (iv) excessively high oil temperature; (v) lack of adequate rinsing of the fryer after caustic cleaning; and (vi) an incorrectly formulated batter. Strict process controls during tempura batter processing will reap many benefits to the processor by reducing waste and maintaining consistent product quality, thereby providing complete customer satisfaction. Acknowledgments The author would like to express his appreciation to James Padilla and Bill Klein of Heat and Control, Inc. for supplying several of the photographs, FMC FoodTech for several of the figures; Monoj Gupta, Neil J. Trager, Andrea Pohl, Terry L. Hogan, and Dr. Christy A. Sasiela for offering valuable critical review of the chapter draft.



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References 1. U.S. Patent 3,245,800, Chicken Frying; H. Sanders; Kentucky Fried Chicken Corporation. 2. Sloan, E.A., Fast and Casual: Today's Foodservice Trends, Food Technol. 56: 3 4 – 5 4 (2002). 3. Leading Culinary Operations, section in The Escoffier Cook Book, Crown Publishers, New York, 1941, pp. 115–116, 123 –128. 4. U.S. Patent 3,622,348, Fish Preparation Method; D. Malin; Arthur Treacher’s Fish & Chips, Inc., November 23, 1971. 5. Suderman, D.R., Batters and Breadings on Food Products, Definitions, in Batter and Breading Technology, AVI Publishing Co., Inc., 1983, p. 2. 6. Johnson, R.T., and J. Hutchison, Batter and Breading Processing Equipment; Ibid., pp. 125, 136. 7. Sasiela, R.J., Formulating Coating Systems for Industrial and Food Service Applications, presented at the IFT/AACC Short Course Science & Technology of Frying, Burlingame, California, May 2001. 8. Hamstra, M., Burger King Attacks McD with French-Fry Launch, Nation’s Restaurant News, New York, NY, December 22, 1997, p. 1. 9. New Lamb Weston Flamethrower FriesTM, advertisement, Nation’s Restaurant News, New York, January 20, 2003, p. 47. 10. New McCain Redstone CanyonTM Seasoned Fries, advertisement, Nation’s Restaurant News, New York, January 13, 2002, p. 25. 11. Processed Fishery Products, U.S. Production of Fish Sticks, Fish Portions, and Breaded Shrimp, 1992 to 2001, National Marine Fisheries Service Annual Report, NOAA, Washington, DC, 2002, p. 51. 12. Buffalo Popcorn Fish, Buffalo Fish Straws TM; sales bulletins #S162, and #S163, Icelandic USA, Inc., Norwalk, CT, 2002. 13. U.S. Patent 6,244,170, Food Product Breading Device; J.A. Whited, L. Bettcher, S.M. Muniga; Bettcher Industries, Inc., June 12, 2001. 14. Sasiela, R.J., Chapter 13, Troubleshooting Techniques for Batter and Breading Systems, in Batters and Breadings in Food Processing, AACC, St. Paul, MN, 1990, p. 231. 15. Brookfield Engineering Corporation, www.brookfieldengineering.com, Stoughton, MA. 16. Sasiela, R.J., Chapter 46, Further Processed Products, Figure 7, in Marine & Freshwater Products Handbook, Technomic Publishing Co., Inc., Lancaster, PA, 2000, p. 360. 17. Sasiela, R.J., Ibid., p. 370. 18. U.S. Patent 6,224,921, Rice Flour Based Low Oil Uptake Frying Batters, F.F. Shih, K.W. Daigle; USDA, May 1, 2001. 19. U.S. Patent 6,288,179, Battered and Battered/Breaded Foods with Enhanced Textural Characteristics, J. Baur, K.S. Darley, J.J. Janda, J.R. Martin, D.B. Bernacchi, I.G. Donhowe; Griffith Laboratories International, Inc., September 11, 2001. 20. Guillaumin, R. (Institut des Corps Gras) Kinetics of Fat Penetration in Food, in Frying of F o o d, edited by G. Varela, A.E. Bender, I.D. Morton, VCH-Ellis Horwood, Chichester, UK, 1988. 21. Flick, G., Y. Gwo, W. Baran, R. Sasiela, J. Boling, C. Vinnett, R. Martin, and G. Arganosa, Effects of Cooking Conditions and Post-Preparation Procedures on the Quality of Battered Fish Portions, J. Food Qual. 12:227–242, (1989).



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22. U.S. Patent 5,527,549, Method of Making Improved Fried Battered and Breaded Foods, Griffith Laboratories Worldwide, Inc., 1996. 23. U.S. Patent 5,601,861, Method of Making Battered and Breaded Food Compositions Using Calcium Pectins, T. Gerrish, C. Higgins, and K. Kresl; 1997. 24. U.S. Patent 5,753,286, Coated Food and Method of Coating, Kerry Industries, 1998. 25. Fry ShieldTM, The Healthier, Lower-Fat Frying Choice, two-page advertising bulletin, Kerry Industries, Beloit, WI, 1996. 26. U.S. Patent 5,217,736, Potato and Other Food Products Coated with Edible Oil Barrier Films, Opta Food Ingredients, Inc., 1993. 27. U.S. Patent 4,917,909, Low Fat Potato Chips and Process for Preparing, GAF Chemicals Corp., 1990. 28. Reduced Oil Absorption and Increased Moisture Retention in Batter-Coated Fried Foods with Methocel Premium Food Gums, four-page technical information bulletin, Dow Chemical USA, Midland, MI, undated. 29. U.S. Patent 5,372,829, Process for Preparing Low-Fat Fried Food, Merck & Co., 1994. 30. U.S. Patent 5,492,707, Process for Preparing Low-Fat Fried-Type or Baked Food Products, Monsanto Co., 1996. 31. Dip System Cuts Fat in Fried Foods, Food Product Design, Newlyweds Foods, May 1994. 32. An Innovative Approach to Enhance the Value and Quality of Breaded Fried Foods, NewlyWeds Fat Barrier 2000 ®, two-page advertising bulletin, Newlyweds Foods, Chicago, IL, undated. 33. U.S. Patent 4,943,438, Bread Crumb Coating Composition and Process for Imparting Fried-Like Texture and Flavor to Food Product, ConAgra, Inc., 1990. 34. U.S. Patent 4,518,620, Process for Breading Food, Central Soya Company, 1985. 35. What is Newly CrispTM?, two-page advertising bulletin, NewlyWeds Foods, Chicago, IL, undated. 36. U.S. Patent 5,770,252, Process for Preparing a Breaded Food, L. McEwen, M. Yurchesyn, K. Wypior; National Sea Products, 1998. 37. U.S. Patent 6,013,292, Low Fat Food Product, Schechter, S., Superior Nutrition Corp., 2000. 38. Baking & Confectionary Section, The Maillard Reaction, Food Technology International, May 2002, p. 112. 39. American Style Bread Crumbs—Your Formula for Success, two-page advertising bulletin, Golden Dipt/Modern Maid Division, Fenton, MI, undated. 40. Kerry Coatings, The Unexpected, 12-page advertising booklet, Beloit, WI, distributed 2003. 41. U.S. Patent 4,068,009, Bread Crumb Coating Composition and Process, J. Rispoli, M. Rogers, and J. Russo; General Foods Corp., 1978. 42. U.S. Patent 4,423,078, Production of Oriental-Style Breading Crumbs, D. Darley, D. Dyson, and D. Grimshaw; The Griffith Laboratories, Ltd., 1983. 43. Coating Handbook for Prepared Foods Processors, Heat and Control, Inc., Hayward, CA, 1999, p. 17. 44. Fresh BreadcrumbTM Fish Portions Coated with Freshly Ground Loaves of Bread, fourpage sales booklet #S324, Icelandic USA, Inc., Norwalk, CT, 2002. 45. U.S. Patent 4,936,248, Breader for Coating Edible Food Products with Fresh Bread Crumbs, Stein Associates, 1990.



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46. Breadings, eight-page advertising booklet, NewlyWeds Foods, Chicago, IL, 1999. 47. U.S. Patent 6,158,332, Convertible Drum-Type Coating Apparatus, R. Nothum, Sr., and R. Nothum, Jr., 2000. 48. U.S. Patent 5,728,216, Continuous Tumble Coating and Breading Apparatus, E.J. London; Stein, Inc., 1998. 49. Food Processing Equipment, A.K. Robins, LLC, advertising booklet, Baltimore, MD, undated. 50. Gourmet Breaders—Thai, one-page advertising sheet, Kerry Ingredients, Beloit, WI, 2003. 51. Taylor, S.L., Allergies to Oil, Food Allergy News, 3:4, 2001. 52. Food Allergy Awareness: An FDA Priority, Food Safety Magazine, Bailey, C., ed., February–March 2001, Washington, DC. 53. Tater CrustTM—Shredded Potato Coated Fish Portions, four-page advertising booklet #S325, Icelandic USA, Inc., Norwalk, CT, 2000. 54. Sasiela, R.J., Troubleshooting Seafood Products—Shredded Potato Coatings, Food Industry J. 5:2, pp. 146–148, Leatherhead Food Research Association, Surry, UK, 2002. 55. HeatWave® Frying System, six-page brochure, Heat and Control, Inc., Hayward, CA, 2000. 56. U.S. Patent 6,067,899, Breaded Products Fryer, A. Caridis, L. Murgel, C. Beitsayadeh, J. Silverter; Heat and Control, Inc., Hayward, CA, 2000. 57. U.S. Food and Drug Administration, Hazards and Controls Guidance, Chapter 15, 3rd edn., Washington, DC, June 2001. 58. Title 21 Code of Federal Regulations, 1–1404. 59. Title 21 Code of Federal Regulations 161.175, 6.

Appendix Some Coated Foods Web Sites* Coated foods regulatory and related web sites: www.fda.gov U.S. Food & Drug Administration: the lead agency for processed seafood, vegetable, cheese, etc., a primary resource for HACCP regulations www.nmfs.noaa.gov National Marine Fisheries Service: a U.S. agency responsible for the inspection of coated seafood www.usda.gov United States Department of Agriculture: a U.S. agency responsible for the inspection and labeling of coated meat and poultry products www.uspto.gov United States Patent and Trademark Office: access to U.S. food patents Batter and breading suppliers’ web sites: www.griffithlabs.com Griffith Laboratories: a global supplier of batter, breading, and seasoning ingredients www.kerryingredients.com Kerry Ingredients: a global supplier of coating, and ingredients, and extrusion technology www.mccormickflavor.com McCormick Foods: a major seasoning and coating ingredient supplier. Print out a useful fry color chart from this site www.newlywedsfoods.com NewlyWeds Foods: a global coating and seasoning ingredient supplier



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www.premiereblending.com

Premiere Blending Company: a supplier of seasoning and coating ingredients www.richmondbaking.com Richmond Baking Company: an Indiana-based manufacturer of unique coarse cracker meals www.washingtonquality Washington Quality Foods: a mid-Atlantic global supplier of foods.com coating ingredients and bakery mixes www.sagevfoods.com Sage Foods: a rice-based coating ingredient supplier www.semills.com Southeast Mills: a supplier of flour-based coating ingredients http://www.extension.iastate. Iowa State University basic primer about batter formulation edu/Publications/N2857.pdf ingredients Batter and breading equipment web sites: www.akrobbins.com A Maryland-based custom manufacturer of coating and other food processing equipment www.bettcher.com Bettcher Industries: an Ohio manufacturer of coating equipment www.fmcfoodtech.com FMC: parent corporation of Stein Equipment Company: an early developer of a broad range of coating and frying equipment www.heatandcontrol.com A major California-based supplier of a broad range of batter, breading, frying, grilling and marinating equipment www.koppens.com A major Holland-based, coating equipment supplier www.nothum.com A Missouri-based coating equipment supplier www.orbitalfoods.com Used batter, breading and frying equipment www.barsso.com/engels.htm Used batter, breading and frying equipment www.used-food-processingUsed batter, breading and frying equipment machinery.co.uk/ stock_list.htm Coated seafood related sites: Website U R L www.nfi.org www.icelandic.com www.seaclam.com www.seaclam.com www.frionor.com

Brief description National Fisheries Institute: a U.S. seafood trade organization Icelandic® brand: a Maryland-based leading supplier of processed seafood products, Icelandic USA, Inc. Sea Watch International, Ltd.: Maryland processor of clam strips, calamari, etc. Frionor: a Rhode Island supplier of processed seafood items, Division of American Seafood Corp. Blount Seafood: a Rhode Island processor of coated scallops, shrimp, mussels Tampa Maid Foods Inc.: a Florida processor of breaded shellfish Singleton Seafoods: a Florida processor of shrimp, and other coated seafood

www.blountseafood.com./ breaded_items.htm www.tampamaid.com www.conagrafoods.com/ brands/singleton.jsp? BrandID=any www.icelandseafoodcorp.com Samband of Iceland brand, division of SIF: a Virginia processor of battered and breaded seafood www.seapak.com Rick-Sea Pak Corporation: a Georgia processor of coated shellfish www.gortons.com Gorton’s: a major U.S. national retail brand of assorted seafood products www.phillipsfoods.com Phillips Foods Inc.: a Maryland processor of coated crab and seafood www.sealord.com Sealord: a New Zealand based seafood processor



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www.vikingseafoods.com www.seafood.ucdavis.edu/ HACCP/Compendium/ chapt02.htm www.mackayeeffish.com/ crumbed.htm www.unilever.ca/Divisions/ bluewater.html www.fpil.com www.mrspauls.com www.kpseafood.com www.tridentseafoods.com www.unisea.com www.st.nmfs.gov/st1 http://ag.ansc.perdue.edu/ aquanic/publicat/govagen/ fas/uk5075.htm

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Viking Seafood Co.: a New England-based processor of breaded fish products Battered fish HACCP guidelines

Mackay Reef Fish Supplies Pty. Ltd.: an Australian fish processor BlueWater Seafoods: a major Canadian seafood processor Fishery Products International: Newfoundland-based seafood processor Mrs. Paul’s Kitchens: part of the Aurora Foods group which also includes major U.S. retail brand Van De Kamps King & Prince Seafood, a Georgia-based processor of shrimp Trident Seafoods, a Seattle-based processor of seafood UniSea Corporation: owner of the Mrs. Friday’s brand, a Los Angeles-based seafood processor U.S. Fisheries Statistics and Economics London Annual Seafood Report

Coated poultry related web sites: www.tysonfoodsinc.com Tyson Foods: an Arkansas-based world leader in processed poultry products www.perdue.com Perdue foodservice: a major East coast processor of poultry Other informative coated products’ web sites: www.1800Poppers.com Formerly Anchor Food Products: a major coated appetizer processor (aka Poppers®), now a division of McCain Foods www.giorgiofoods.com Giorgio Foods: Pennsylvania processor of coated mushrooms, cheese sticks, appetizers www.phillipsfoodsinc.com Phillips Foods: a manufacturer of breaded mushrooms and appetizers www.jon-linfoods.com Jon-Lin Frozen Foods: a California manufacturer of breaded onion rings, squash, fruit, and battered French toast sticks www.simplotfoods.com Simplot Foods: a major processor of coated potato, and finger foods www.lambweston.com Lamb-Weston: another potato powerhouse with seasoned and coated fries www.mccainusa.com Manufacturer of seasoned French fries and other appetizers http://www.fosterfarms.com California-based processor of poultry and various corn dogs www.jimmydean.com Corn dog manufacturer *Note: Web sites often change and are solely guidelines; therefore, conduct a search if a listing is not responsive. Some sites require registration. No company or product endorsement is made by its listing here or elsewhere in this chapter.


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Chapter 10

Fried Foods and Their Interaction with Packaging Kenneth S. Marsh Kenneth S. Marsh & Associates, Ltd., Seneca, SC

Packaging Functions Packaging plays a number of critical roles for fried foods. Consistent with virtually any food product, it must contain the product, protect it against moisture, oxygen, and sometimes light, and protect it against shock, vibration, and mishandling during storage and shipping. The packaging must present information consistent with the regulatory requirements. In addition to these protection functions, packaging helps present the product in a manner that differentiates it from competitive products to attract purchasers. This diversity of functions crosses company departmental boundaries, which can lead to conflicts and disagreements, with various groups working on the product having different objectives. For example, purchasing may seek the least expensive package material; marketing prefers the most impressive option; production is easier with a loose package, but distribution damage is reduced with a snug package. Therefore, the selection of packaging material for a product can become a complicated process in a corporation in which multiple groups are involved in making the decision. A humorous manifestation of this occurred when the corporate director of packaging for a Fortune 500 company put a nonmoisture-, nonoxygen-sensitive food product packaged in a Kraft bag (commonly referred to as a brown paper bag). He presented the bag at a marketing meeting that included senior management. To the incredulous committee he stated that his proposed package satisfied the protection requirements, and anything more should be considered as marketing expense. The point is that the package must both protect and present the product. Consumers are exposed to many packages during their supermarket ventures. Any package, therefore, has little opportunity to grab the consumer’s attention. Competition for attention in the supermarket is extremely fierce. Studies suggest that the time to gain the consumer's attention ranges between a few seconds and tenths of seconds. Mr. Harckham recommends that the company line therefore make a statement as the consumer comes down the aisle, and then each individual product differentiate itself when the consumer is in front of the shelf. His example was not fried foods, but illustrates the concept. Lipton soups (as do Campbell's) exhibit a strong presence with strong red and white bands, which tell the consumer “Here are Lipton soups.” The graphics presented to consumers looking directly at the shelf, however, clearly differentiate one flavor from others. A critical look at


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other company products will show whether their products compete as a company or as individual products. Company identity through creative packaging and presentation can greatly influence a consumer's attention. Procedures to specify protection functions and distribution requirements will be presented later in this chapter. The following will present generalized requirements for various types of foods. Packaging Examples Bakery. Bakery products typically require a short shelf life because their “raison d’être” is freshness. Products may require some moisture protection, and often require grease protection, not for the product, but for the product presentation. Grease spots on a package would detract from the clean appearance of a fresh product. Typical materials are coated board and coated papers in which the coatings may be polyethylene or wax, either of which provides both limited moisture protection (if sealed) and resistance to grease wicking. Packaging examples for bakery items will utilize donuts. Similar packages also apply to other bakery items. Figure 10.1 shows donuts in a thermoformed polystyrene (PS) tray. This represents an inexpensive packaging material, with high clarity, rigid feel, a hinged cover, which facilitates reclosure, but which offers little moisture or oxygen protection. As with the following examples, low barrier protection is appropriate because of short shelf-life requirements. Figure 10.2

Fig. 10.1. Thermoformed polystyrene tray.


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Fig. 10.2. Use of a window box in a coated board box.

exhibits a window box, which offers product visibility in a coated board box, whereas Figure 10.3 illustrates windowed bags, which contain a grease-resistant coating or treatment to avoid wicking and polymer bags for donuts. The polymer bag, which shows the entire product, is also formed on the packaging line and offers faster line speeds to the manufacturer.

Fig. 10.3. Window bags with a grease-resistant coating and polymer bags.


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Fig. 10.4. A tray with overwrapped film.

Figure 10.4 shows donuts in a tray with overwrapped film. The tray can be expanded polystyrene (EPS), PS, polyolefin, polyester, or expanded polyolefin. The overwrap may be polyvinyl chloride (PVC), polyolefin, or other polymers. This package offers a fresh bakery look and shows the product. A final option is presented in Figure 10.5, which shows fresh bakery, i.e., no package. This option

Fig. 10.5. An example of no packaging—fresh baked goods.


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provides the shortest shelf life, but suggests freshness. It offers the customers the opportunity to mix and match different varieties into a single purchase. From the environmental perspective, “no package” offers a nonpolluting option, but also gives no protection to the product. It makes labeling difficult (must be supplied through external media). Snacks. Snack items usually require oxygen and moisture protection because these products are typically low in moisture (to provide crispness) and high in oil content. The protection requirements will relate to the expected shelf life, i.e., the length of time between production and consumption, which in turn relates to the distribution system and the distribution environment. A number of possible tradeoffs exist. Controlled temperature (and possibly relative humidity) during warehousing will influence the amount of moisture pick-up and oil degradation in the product. However, this is a costly proposition. A distribution that allows more rapid deployment of the product distribution, such as the Frito Lay system, can reduce the packaging protection requirements. In addition to chemical protection, packaging must offer protection from physical abuse from shock, vibration, and compression. Much of this function is borne by the distribution package, typically a corrugated shipper, or overwrapped tray. The primary package (the package in direct contact with the product) also plays a role. Cans provide stacking strength and shock protection. Corrugated boxes offer less stacking strength than cans, but actually can provide more shock protection because paperboard will absorb rather than transmit shock pulses. Polymer pouches also provide shock protection if the pouch is inflated before sealing. Potato or corn chip pouches, for example, are typically inflated, often with nitrogen to reduce oxidation and to provide protection against shocks. Tip: Testing protocols for distribution packages, such as the ASTM D4169 (1) and ISTA procedures suggest drops be made on different orientations of the shipper, and on surfaces, edges, and corners. Usually the different orientations (bottom, side, end, top) are included to test shippers falling on these alternate panels, with the “normal” (bottom facing down) orientation set. It is recommended that one must look at the results to determine whether an alternate orientation offers better protection [by exhibiting a higher effective free fall drop height than the normal configuration (2)]. If this is true, consider changing the product orientation in the shipper to provide additional protection with virtually no cost increase. Unlike the donut examples above, snacks typically have longer shelf lives and therefore require more barrier protection than that offered by coated paperboard containers. Therefore, most snacks are packaged in polymeric films with a wide range of moisture and gas barrier properties. The amount of protection relates to the shelf-life requirements, and the storage environment. An important trade-off is possible in which the distribution system affects the packaging requirements. Frito Lay has developed a system consisting of ~50 manufacturing plants and 900 distribution centers (DC). This system allows products to


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be manufactured and delivered to the retail facilities within weeks, and more often within days after production. This rapid deployment reduces the protection requirements of the package. Therefore, Frito Lay can present fresher products (or more oxygen-sensitive products) to the store shelves more rapidly than would be feasible with a more modest grocery distribution system with fewer plants and DC, simply because they can obtain product. The simplest and least expensive snack package is a polyolefin bag, such as the linear low-density polyethylene (LLDPE) bags. These bags offer moisture protection but no oxygen protection; therefore, they are used for products that will sell quickly, or are not expected to exhibit rancidity during the time they remain on the shelf. Orientation of the polymeric films improves both clarity and barrier properties. Figure 10.6 presents an example of bags with these properties. Clear bags can be made from single or multiple films. Laminated or co-extruded structures allow for combinations of properties that are more suitable for a given product than those available through any single film. For example, oriented polypropylene (OPP) provides a moisture barrier but little oxygen barrier. Incorporating a barrier layer, such as ethylene vinyl alcohol (EVOH) or polyvinylidene chloride (PVDC) can add substantial oxygen barrier to the package. Because these barrier materials are usually more difficult to seal, a heat seal layer is added as the inside layer. Clear bags with the added barrier properties have the advantage of showing the product, as seen above in Figure 10.6. Aluminum may add high oxygen and light protection to a laminate. Aluminum foil is essentially impermeable to oxygen and moisture as long as it is free of pin-

Fig. 10.6. Clear bags made of linear low-density polyethylene.


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holes or cracks. Because foil does not provide an easy sealing mechanism and is prone to tearing in thin films, the barrier is achieved by incorporating thin foils into a laminated structure. Pouches with a foil barrier provide excellent oxygen protection. These gusseted pouches will stand vertically on the shelf and help sell the product. Foil can also be incorporated into structures in which paperboard is utilized to provide strength and rigidity. A Pure-Pak container can be incorporated with aluminum foil to achieve the barrier properties. Composite cans of various shapes and sizes (Fig. 10.7) use a thicker paperboard layer to add rigidity and stacking strength to the packaging. The preformed potato sticks cans in Figure 10.7 were initially protected from impact with a corrugated medium placed between the chips and the composite can, but this protection is no longer used. Aluminum provides other attributes that allow the container to become part of the product. The foil pan (Fig. 10.8), which is thicker than foils used in laminates, is used to cook the popcorn, and clearly differentiates the enclosed product from competitors with valueadded features. Although many snack foods are packaged in foil laminates, most current snack packages now use metallized substrates (Fig. 10.9). Aluminum is sputtered onto films in extremely thin layers, thereby using considerably less aluminum than even the thinnest foils. One can differentiate foil structures from metallized structures by cupping a bag snugly against one’s face and looking directly into the bag toward a bright light. The presence of pinholes of light and thin lines (cracks in the foil) indicate that the structure contains foil. Metallized films will transmit light through the material, and the amount of light transmitted will be inversely proportional to the amount of aluminum lay-down, and the amount of printing inks. If little light

Fig. 10.7. Composite cans have a thicker paperboard layer to improve rigidity and stacking.


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Fig. 10.8. Use of an aluminum container as part of the product (foil pan) clearly differ-

entiates it from competing products (bottle and gusset pouch).

comes through, the lay-down is heavy; if light comes through easily, the lay-down is light. The degree of barrier properties in a packaging film is a function of the amount of aluminum and the contiguity of the layer. Extremely thin lay-downs of aluminum may provide a bright metallic appearance to the package and printing, but provide little barrier properties. For example, an overseas airlines company discovered that their peanuts were becoming rancid. The degree of metallization on the peanut pouches was found to be very light so that the oxygen barrier was not significantly enhanced over the base material. The perception was that they were employing a barrier material, which was not the case. The aluminum metallization in this case gave a metallic appeal to the graphics, but offered almost no barrier enhancement. The solution was to improve the amount and integrity of the aluminum lay-down and thereby improve the barrier properties of the film. The attraction of a metallized substrate can be combined with a presentation that shows the product by using pattern-metallized films, which leave a clear window. The dynamic graphics that resulted from inks printed on foils or metallized films became so ubiquitous that one company introduced a matte finish to differentiate their product. This finish was identified as a deli look, which suggested freshness. An extension of packaging snacks as individual products is the multipack, which allows a forum for consumers to try other products in a company's line. Snacks that are less susceptible to environmental influences, such as popcorn kernels, may be packaged in boxes. This option is also used for more sensitive products, such as butter-flavored popcorn (oxygen sensitive) with a bag-in-box


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Fig. 10.9. Metallized substrates (aluminum).

package. Consumer benefits may be enhanced with susceptor inserts which focus microwave energy to concentrate heat and promote browning or popping (Fig. 10.10). Additional convenience was mentioned earlier with the popping pan. Other presentations of snack packaging include bags clipped to a display rack, or low barrier snack bags. Potato chips represent a large portion of fried snack products and illustrate many packaging challenges. Additional discussion of the technical aspects of potato chips (as a representative of this and other fried chips) is therefore warranted. The bulk density of potato chips is typically 0.056 g/mL. This is a light product with a very large surface area. As a result, the headspace in the package, if air, would contain sufficient oxygen to oxidize the oils used in the frying process. Air allows uptake exceeding 3 mL O2/g at STP (standard temperature and pressure). With sufficient oxygen within the package, the oxygen barrier will provide disappointing results. The solution is to exclude the oxygen from the package before sealing, and then maintain low oxygen within the package by appropriate barrier materials. Therefore, an inert gas, typically nitrogen, is used in the packaging of fried snacks. Very significant increases in storage life are realized if: • Oxygen (O2) levels in the headspace are kept below 2% • Oxygen (O2) barrier films are employed • A light barrier is incorporated into the packaging film


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Fig. 10.10. Use of bags in a box for microwave products.

Studies that compare different materials used for potato chip pouches were compiled by Robertson (3). A polyethylene bag whether high density (HDPE) or low density (LDPE) (moisture barrier, but poor oxygen barrier) provided a 15-d shelf life at 27°C, 65% relative humidity. A PVC/PVDC copolymer-coated polypropylene bag provided 8–10 wk shelf life before the chips were unsalable due to loss of crispness. Potato chips packaged in polypropylene (PP)/aluminum foil pouches lasted ~27 wk before becoming unsalable due to rancid flavor development. Chips packaged in OPP/LDPE/PVC, HDPE/EVA copolymer with an ultraviolet light (UV) absorber developed a distinct oxidized flavor within 7 d of storage at 21°C and 55% relative humidity under 140–230 foot-candles of continuous fluorescent light. Potato chips stored under similar conditions, but with a brown lightabsorbing pigment or an aluminum foil/LDPE construction were stable for 10 wk of storage. The code date for a product is dictated primarily by the distribution system of the company. The product can fail due to moisture uptake and/or oil oxidation during distribution and storage. Shelf life of the product can be ensured by careful selection of a packaging material that offers the required moisture and oxygen barrier properties. The extended code date for a product is achievable at a cost. This requires a careful evaluation of the overall need for product protection, distribution time, and the systems that are in place for a given product. Frozen Fried Foods. Frozen foods are protected by temperatures that slow oxidative, chemical and biological reactions and bind water (in the form of ice), thus eliminating possible access by microorganisms. The storage temperature is the major player in protecting frozen foods. Fried foods require little packaging protection. However, no freezer maintains a constant temperature. Frost-free freezers eliminate frost by periodically heating the freezer walls and thereby driving off frost. In addition, the temperature rises every time the freezer door is opened, and is brought down again after closing. As a result, temperatures fluctuate in the freezer.


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The water-holding capacity of warmer air is greater than that of colder air. Even if the freezer temperature rises just a few degrees, the air space in a package will hold more water. Water sublimes (converts from ice directly to vapor) from the product in the package and increases the relative humidity in the package headspace. When temperatures fall, water-holding capacity decreases and water condenses onto the colder surface. Because the chilling is external, the colder surface is the package, and ice crystals form on the inside surface of the package. The cycle, therefore, is that water leaves the product and condenses inside the package, resulting in “freezer burn,” which is a textural change in the product caused by localized drying. Reduced headspace in the package can minimize this problem. The tighter the package, the smaller the effect, with vacuum packaging being the most effective for this purpose. The recommendation for frozen foods, therefore, is to make the package as tight as feasible for any product. A simple package is a polyethylene bag (Fig. 10.11). It has the advantages of low cost and resistance to fats and oils. Paperboard is also used (Fig. 10.12), but paperboard consists of hydrophilic cellulose fibers, which can wick oils and make the package unsightly (as mentioned above with bakery products). Coatings or polymers are used to prevent wicking. This is why most paperboard containers that are in direct contact with frozen fried products are coated. Another way to separate product from contacting a paperboard container is to employ an internal container, such as a bag or tray, for the product (Fig. 10.13). Other Fried Products and Outlets. Most of the products mentioned above are sold through traditional grocery systems or smaller retail outlets such as convenience stores and gas stations. Bakeries, which used to be separate facilities, are increasingly incorporated into supermarket chains. Additional trends are home

Fig. 10.11. Frozen product in polyethylene bag.


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Fig. 10.12. Frozen product in paperboard container.

meal replacement (HMR) systems in which prepared meals are offered at supermarkets in competition with restaurants, and kiosks in which specialty products are grouped for sale. Both of these developments offer freshly prepared foods for today’s meal. They also offer new snacks such as fried pies with overwrap.

Fig. 10.13. Paperboard container with an internal container, e.g., a bag or tray.


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Packaging Systems for Fried Foods: Selection and Evaluation The previous section illustrates the many options for packaging of various fried foods. This section will cover the technical aspects of the packaging choice, that is, those aspects that provide suitable protection for the product itself. This protection includes the barrier requirements, which define the shelf life of the product, and physical protection, which allows the product to survive the distribution system. The primary protection, which defines the shelf life of the product, will be discussed first. Distribution protection will follow. Shelf Life. The company manufacturing and distributing the product must define the shelf-life requirements for any product. Often a group of employees (a committee) performs the task of specifying the desired shelf life for a product. This process might be based on experience with existing products and past experience. The company’s product distribution system plays an important part in determining the desired shelf life of the product. The choice of shelf life has a significant effect on the image and profitability of the product. A major consideration for shelf life is the stability of the product itself. Any product containing unsaturated fats or oils will be prone to oxidation; thus, the product will be oxygen sensitive. Fried products are also dried (moisture flashes off during frying) and are usually also moisture sensitive. It deserves mention that the type of package will directly affect product shelf life. For example, a snack item, which (in packed form) becomes soggy in 1 mo, and becomes unacceptably rancid in 4 mo, will be viewed as moisture sensitive because it first becomes unacceptable through a moisture gain. The same product, with a moisture barrier that is adequate for maintaining crispness will be viewed as an oxygen-sensitive product. In addition to the primary protection for shelf life, the package must protect the product through the distribution environment. This has been mentioned earlier and will be discussed in detail later in this chapter. Company philosophy affects the packaging choice. A company that competes on price may choose an inexpensive package providing limited shelf life (minimum barrier), and possibly simplified graphics for cost containment. Alternatively, a company may choose a premium image, with better packaging, longer shelf life (or higher quality within the shelf life through better barrier), and more attractive art work. The distribution system, as previously mentioned, also affects the selection of the packaging material. The goals for packaging can be stated as follows: to provide adequate protection for the product from production to consumption, to be cost effective, to be able to be handled by the packaging machinery at the plant, and to be environmentally responsible. In addition, it must also present, inform, and help sell the product. Many criteria are used to define shelf life. As a general rule, business efficiency is enhanced when the production capacity, inventory capability, and distribution system are taken into consideration to define the shelf-life requirement for a prod-


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uct. This requires knowledge of the distribution system and the production of sufficient product to maintain the pipeline with product plus sufficient surplus to maintain the supply. The business model, therefore, is to produce product with a shelf life that matches the distribution system and meets the product quality standards as desired by the customers. The packaging barrier properties required to provide the needed shelf life for a product will vary with the package size. The same product packaged in a smaller size has a shorter shelf life than that in a larger package because the larger package has less film surface area per unit weight of the product in it. Therefore, the product in a larger package comes in contact with a smaller amount of moisture and oxygen diffused into the package compared with a smaller package within the same time span. Therefore, for a given product and package shape, the larger the product size, the lower the barrier requirements necessary for a given shelf life. With this in mind, let us discuss barrier properties of different packaging materials. When choosing a packaging material, it is prudent to remember that the barrier properties of packaging materials vary widely. Glass and metal (such as cans or foils) are the only materials that provide an absolute barrier to gases (such as oxygen) and vapor (such as moisture). Even these materials supply an absolute barrier only if they have full integrity. Rigid containers of either glass or metal must be sealed, and the sealant materials also have a finite barrier property. Some gases and vapors can permeate through the sealant. Therefore, metal cans or glass containers provide good protection but are not absolute. Foils are good barriers as long as t h e y have no pinholes or cracks. However, thin unprotected foils are prone to both pinholes and cracking. This is why foils are usually laminated to polymers and/or paper to make the material more resistant to damage in handling. The ultimate barrier property of the packaging film depends on the choice of laminate and the thickness of the layers, including the foils. Plastics can provide a wide range of barrier properties to both gases and moisture. No polymeric material supplies an absolute barrier. Figure 10.14 presents a number of packaging materials that are currently used or have historically been used for packaging snack foods. The values are representative of particular polymers, but keep in mind that different resins with the same name may vary in permeability characteristics (i.e., check with suppliers). The graph shows that some polymers, such as polyolefins, comprise a relatively good moisture barrier, but poor oxygen barrier. Other materials, such as EVOH, are excellent oxygen barriers, but poor moisture barriers. PVDC and METPET (metallized polyester, with good lay-down) are excellent barriers to both gases and moisture. Figure 10.15 presents the barrier properties in a different format, i.e., the cost of sufficient polymer to provide an arbitrary unit of barrier performance. All of the oxygen barriers are the same, as are all of the moisture barriers. The graph shows that using polyethylene for the oxygen barrier, for example, would be very costly because an unreasonable wall thickness would be required to obtain the desired level of oxygen barrier. This material, however, provides a cost-effective moisture


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–WVTR

–02TR

Fig. 10.14. Film permeabilities. Source: Kenneth S. Marsh & Associates, 1985, with

permission.

barrier at a reasonable thickness, although HDPE, a more expensive resin, is more cost effective for moisture protection. A very thin EVOH film will provide an excellent oxygen barrier, but would be too thin to provide a suitable package. EVOH is therefore typically incorporated into a laminate to provide the gas barrier while other components add mechanical strength, moisture barrier, and heat stability. Specific strength and barrier properties, therefore, can be designed in a cost-effective manner with an appropriate choice of polymer combinations in a lamination or coextrusion. Packaging materials must be evaluated to determine the shelf life that they will provide for a given product. This is usually determined through storage studies at both ambient and accelerated conditions. High-temperature/high-humidity storage studies do accelerate degradation and allow for more rapid assessment of performance than ambient studies, but the kinetics (reaction rates) will vary with products and must be evaluated with the specific product before accelerated tests can be evaluated correctly. Any program that states that an accelerated condition is some multiple of ambient is valid only if it has been verified on a specific product through a statistically validated test. Mathematical modeling can be employed to shorten the time required to test packaging materials. The first step is to determine limits for any agent that defines


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–WVTR Protection

–02TR Production

Fig. 10.15. Relative cost of different barriers. Source: Kenneth S. Marsh & Associates, 1985, with permission.

the quality of the product. For snack products, this often includes moisture, which affects texture, and oxygen, which promotes rancidity. For all products, there is an upper limit for moisture content and the degree of oil oxidation in the fresh product. A threshold value for each of these parameters also exists to define the end point for consumer acceptance. It is necessary to meet the maximum moisture and oil oxidation standards in manufacturing. The packaging material is then chosen to match the desired shelf life, given the product distribution system in place. Although a target value may be specified for any critical parameter, production variability exists. Furthermore, the acceptable range, which is defined by the company, is ideally wider than the production range (Figure 10.16). If this were not true, the product would have no shelf life. The amount of oxygen or moisture that can be tolerated is the amount that can be absorbed between production and threshold or acceptable levels. Again, the quality acceptance criteria will be related to those points that are chosen on the basis of consumer acceptance data. Once an acceptability range is established and a quantity of permeant is specified, barrier requirements can be calculated. For example, if a product is known to be able to tolerate x grams of oxygen before it becomes unacceptable, one can calculate the barrier required to allow x grams during the shelf-life requirement at a specified storage environment. A simple calculation is to define the oxygen trans-


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Process condition Fig. 10.16. Quality profile. Source: Kenneth S. Marsh & Associates, 1991, with per-

mission.

mission per day and match that to barrier specifications of films. However, such a procedure will overspecify barrier because transmission changes as oxygen levels increase within the package (Figure 10.17). A more accurate procedure will compensate for the changes in oxygen level. Calculations of minimum barrier requirements for a given shelf life provide a means to choose suitable barrier materials. It is still prudent to verify the choices with storage studies, but such studies can be restricted to confirming materials that are likely to succeed and eliminating those that are not likely to provide the required shelf life. Furthermore, if both ambient and accelerated shelf-life studies are performed, the kinetics can be determined such that accelerated studies can be properly evaluated for future studies. In addition to barrier requirements, other means can be used to extend shelf life. For example, nitrogen flushing removes oxygen from the package. Oxygen or moisture absorbers (active packaging) can also be employed to reduce the effects of agents that permeate the package. Packaging films are now available that absorb oxygen as it is permeating the film, thereby reducing the influx into the product. Shelf life can be influenced by changing environmental conditions, which are typical for noncontrolled distribution systems (controlled is refrigerated and frozen distribution). High-temperature, high-humidity conditions experienced early in the distribution cycle will have a more detrimental effect on shelf life than similar conditions experienced later. Figure 10.18 shows the shelf life of a food product vs. month of production. Products shipped during the summer months had shorter shelf lives than those produced during cooler periods. Furthermore, as expected,


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Time (mo) Fig. 10.17. Permeant accumulation. Source: Kenneth S. Marsh & Associates, 1991, with

permission.

Month of production Fig. 10.18. Shelf life vs. month of production. Source: Kenneth S. Marsh & Associates,

1984, with permission.


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the shelf life of products shipping to warmer locations had reduced shelf life (unless stored in climate controlled warehouses). Such information could be used to improve product performance by possibly changing packaging requirements (if regionally produced) or advertising to improve product flow through more critical regions. Physical Protection. Physical protection can be achieved through the primary packaging container, such as nitrogen injection into potato chip bags as mentioned earlier, or through the distribution packaging, such as a corrugated shipper. Additional cushioning may be employed if necessary. The physical requirements are typically defined through distribution testing. In years past, this was performed with shipping tests in which product was sent through distribution and evaluated for damage. Simulated testing is now typically performed on packaged products. In this test, packages are shock-tested to simulate impacts, vibration-tested to simulate transportation forces, and compression-tested to simulate warehouse stacking. Standard procedures are available through the American Society for Testing and Materials (ASTM) and International Safe Transit Association (ISTA). The simulated testing procedure must be appropriate for the distribution system through which the product is shipped. Applications that vary widely from standard conditions should be carefully evaluated against the test results. For example, field supplies for military operations may need to pass a standard for helicopter drops (150-ft drop at 100 knots with 75% survival) that is significantly greater than grocery distribution, but designed for an appropriate critical operation. The distribution packaging must be designed to withstand the shock experienced through the distribution system. The ability to do so is often expressed as the effective free-fall drop height (EFFDH), i.e., the highest level from which the product can be dropped and withstand an acceptable level of damage (Table 10.1). The greater this value is, the greater the height from which it can be safely dropped. Keep in mind that heavier products typically experience lower drops in

TABLE 10.1 Fragility Evaluation Drop Tests Effective free fall drop (in) Product

Base

Side

End

Chips I Chips II Snack I Snack II Snack III Snack IV

14 17 24 24 34 18

14 11 6 52 60 18

32 17 30 19 25 18


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distribution. For example, a unitized shipment on a pallet will experience much lower drops than a single package. Vibration occurs during transportation, and varies with the mode of transport, such as truck, rail, ship, or air. Most food products do not have sufficient profit margins to justify additional cushioning materials to dampen vibration. Compression strength is critical for stacking strength, and specifies how high pallets may be stacked. The distribution testing is performed with packages that have been equilibrated to standard conditions, usually 73°F/50% relative humidity. This is done to allow comparison among different studies and different testing laboratories. If storage conditions differ from standard conditions, it is important to recognize that compression strength may not match expectations. Storage in hotter, humid environments will severely reduce the compression strength of corrugated packaging. The author strongly advises that anyone who specifies packaging for food (or any) product should follow the product through the entire production and distribution system. This includes observing incoming quality assurance for the raw materials and the packaging material that are used to make the product, production, transport to the warehouse, warehouse operation, transport to retail outlets, the logging of product, stacking onto the retail shelves, and use of the product. Such an analysis may uncover anomalies in the system that alter the product in a disproportionate manner. Many companies either assume that they know these systems, or anticipate a certain level of performance. Actual observations of these various systems may suggest ways to improve the product, improve the package, or improve the distribution system, and ways to improve profitability. Improving profitability with packaging systems does not necessarily mean decreasing packaging costs. The author evaluated the distribution system for a frozen product and discovered that a disproportionate amount of damage was caused during the log-in process at the supermarket chain. In high humidity environments, moisture condensed onto the product, which had to be exposed to be logged in. A carton improvement and moisture-protective coating increased packaging costs by $200,000 per year, but resulted in a $1.7 million reduction in damages. Reducing Distribution Costs. It is recommended that the product be followed through the distribution system to better understand the following: • How the packaging performs throughout the distribution system • Where damage may occur in the system Once the information is collected and the system performance is understood, one must take the following steps: (i) define the action steps needed to correct the issues; and (ii) take appropriate action to improve performance. These principles may be extended with increased knowledge of the entire system. The above discussion of shelf life included a description of changes in shelf life that result from changing environmental conditions. Analysis and documentation of these changes may offer additional means for improving profits. It is possible to utilize this infor-


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mation to improve profitability if one studies the effects of various city climates in relationship to the actual product shelf life obtained in the various geographic locations. The company could try to better match distribution system to product turnover rates as suggested in Figure 10.18. One could modify advertising and coupons to accelerate the sale of products in warmer climates if the packaging was designed for these more critical regions. Such action may enable the company to reduce the cost of packaging, thereby resulting in a major savings. It suggests that one could design the package for the entire market as opposed to the worst geographic location. Another option for varying regional performance is to vary regional packaging. This requires additional product codes, which obviously means additional expense. However, if the savings in packaging materials exceeds these costs, profit improvement is achieved. The practicality of this option depends on its economic viability. An additional benefit of studying distribution environments is that it allows comparison between new and existing markets. For example, a domestic company that wishes to expand to foreign markets may evaluate additional packaging requirements to meet the needs for those markets. Modern technology can be employed to carry this concept further. The author has proposed a Computer-Aided Distribution in which temperature/humidity sensors could be installed in distribution centers and possibly transport vehicles and containers. These sensors could record the actual conditions that specific products have experienced, and be used to pull products on the basis of available shelf life instead of first-in/first-out systems that cannot compensate for abused product. This system would require a database consisting of all shipments with dates, destinations, and environmental readings, a computer program to calculate available shelf life, and an interface that modifies pull dates of products in the specific distribution center. Needless to say, it would require a highly sophisticated computer system that the distribution staff would have to follow exactly.

Conclusions The author strongly advises any person who is responsible for the design or specification of a packaging system to follow the product through its entire manufacturing and distribution system periodically and observe products in the entire distribution system. Such action will demonstrate how well the system is performing. Viewing products in distribution will also suggest how products compare with competition, which may well lead to ideas that may benefit the company. Testing and evaluation of actual product through distribution conditions can pinpoint problem areas. Any aspect of these areas that results in a disproportionate amount of product damage makes them the focus of opportunity for profit improvement. Packaging can reduce damage and improve sales. A relatively common practice is to choose the lowest cost packaging material for a given product. This may appear to be a sound business option, but it may compromise profitability in the


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long run. Often there is a trade-off among product, packaging, distribution, and a more protective package. The final decision should be based on profitability. Packaging that promotes sales through better presentation, and convenience features such as easy opening, resealable pouch, and so on may not only enhance sales, but also allow for consumer acceptance of a higher price. Packaging attracts customers at the supermarket and plays the role of principal salesman for the product at the store. Therefore, it is directly related to the company's profitability. The package will influence the initial sale; the product quality will determine repeat sales. References 1. ASTM D4169-94, Standard Practice for Performance Testing of Shipping Containers and Systems, American Society for Testing and Materials, Philadelphia, 1994. 2. Marsh, K.S., Influence of Product Orientation on Shock Resistance of Snack Foods, Packaging Technol. Eng. 8:36 (1999). 3. Robertson, G.L., Food Packaging: Principles and Practice, Marcel Dekker, New York, 1993.


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Chapter 11

Toxicology of Frying Fats and Oils Richard F. Stier Consulting Food Scientists, 627 Cherry Avenue, Sonoma, CA 95476

Introduction Fatty foods, especially fried foods, are enjoyed by people of all countries, and fat has been used for thousands of years by almost every civilization. No matter where one travels, these delicious products are offered as part of the daily fare. In Europe, frites and fried pastries are mainstays of the diet. The Chinese produce a fried dough product bearing a name that literally translates as fried rope. Tempura, a fried battered product, is a staple of Japanese cookery. Fried and seasoned grains, chips and wafers have been part of daily snacks in the subcontinent of India for centuries. A small sampling of popular fried foods in the United States includes French fries, fried chicken, fried snack foods (chips and nuts), donuts, pastries, and pies. Modern day consumers have been made to believe that the foods that are tasty and rich in taste are bad for one's health. Many physicians have called all fried foods “bad” because they are fried in oil and are rich in fat calories. To some degree, this is true because overindulgence of any type of food, whether it is rich or lean in energy, could be harmful to health. In addition, some consumer advocates have indicated that frying generates compounds that could pose health hazards. Deep-fat frying is probably one of the most dynamic processes in all of food processing. The oil, as well as the fried food, undergoes dramatic chemical changes during the frying process. The oil is subjected to prolonged heat stress that can break down the oil, producing a large number of compounds that can affect the flavor, taste, and storage life of the product. Some of the oil breakdown products may cause some gastrointestinal distress when the food is consumed in very large quantities. In reality, properly operated fryers do not heavily damage frying oil, and the oil does not pose any toxicological danger. Concern over the health implications of oil and fried foods have led to a great deal of research in this area. A considerable amount of research has been performed over the past six decades. Researchers have tried to understand whether normal frying generates any harmful compounds in the oil or fried foods and whether heated and/or abused oils are safe for human consumption. Most of these studies were conducted on laboratory animals to determine: (i) the effect on health and longevity of the test animals, their organs, and survival; and (ii) food utilization, absorption of nutrients, and the growth pattern of the test animals. The majority of the feeding studies utilized oils that were heated and abused excessively. No frying operation, whether industrial or restaurant, would treat the


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fryer oils in the way these researchers did. Therefore, one must exercise proper judgment when drawing conclusions from the studies. However, this kind of laboratory research has been and will continue to be extremely important. Studies with heated fats and oils do provide the regulatory agencies with the background information for enacting laws and/or establishing guidelines to protect the health and welfare of the consumers. This chapter will review the effect of heated oils on human health.

Dietary Issues There have been several major changes during the past two decades in consumer, industry, and government attitudes toward the consumption of fats and oils. Fats or oils have been labeled as one of the less desirable constituents in our daily diet. These findings have spawned the proliferation of so-called “Low-Fat” and “FatFree” products in almost every category of packaged foods. Unfortunately, fats and oils (lipids), along with proteins and carbohydrates, are the primary nutrients in the human diet. Without some fat, the diet is incomplete. The studies conducted by the Surgeon General of the United States indicate that consumption of low-fat and nofat products has not produced a leaner population. Unfortunately, the contrary is true, and the U.S. population is getting fatter. Early Research Work on Heated Oils Research on frying fat and oils began in the early part of the 20th century. The home economics departments of various universities in the Midwest took the pioneering role in this area. Studies were conducted in the early 1930s to determine the nutritional effects of heat on fats. Morris and his colleagues (1) reported that rats given heated lard as their diet developed vitamin E deficiency. Their work also showed that rats suffered growth failure and weight loss when their diet contained 50% lard that was heated for 120 min at 300°C. Roffo (2) reported that rats developed tumors when their diet consisted of sunflower oil, olive oil, lard, tallow, or cholesterol that had been heated for 30 min at 350°C. Later workers refuted these findings on the basis that the tumors failed to meet the established criteria for cancer. Crampton and Millar (3) observed that rats had a high rate of mortality when they were fed a diet consisting partly of polymerized linseed oil. The linseed oil was heated for 6–15 h at 275°C with carbon dioxide sparged through the oil to exclude air. Harris (4) reported that laboratory rats suffered impaired growth and ill health when they consumed fish oils heated for 8–12 h at 280°C. Lane et al. (5) observed no tumor formation in rats when the diet consisted of oil browned for 30 min at 350°C. These rats, however, seemed to have a higher incidence of papillon and ulcers. Lassen et al. (6) showed that sardine oil that had been heated to high temperatures was less digestible than unheated oil. Crampton and his colleagues reported results in a series of papers in 1951 (7). In one study, the rats received a diet of baked feed consisting of 10–20% of linseed, soy,


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cottonseed, rapeseed, corn, peanut, or herring oil. The oils were individually heated for 30 h at 275°C and then incorporated into a baked product. Baking was done at 375°F for 20 min. Test rats receiving the diet containing 20% heated oil showed increased weight loss. The linseed oil diet seemed to have the worst effect on the rats. In a second study by Crampton et al. (8), the heated linseed oil was fractionated by a distillation process into distillate and residue. Heavy mortality and overall poor health were observed in the group administered the residue fraction in their diet. The distillate fraction was found to be relatively less harmful to the rats, but was more deleterious than the unheated oil. Deuel et al. (9) made citric acid esters of glycerol. The esters were heated for 8 h at 205°C and potato chips were fried with the heated ester. Rats were fed a diet consisting of heated esters and fried potato chips. Neither diet had any adverse effects on the test rats. Frahm et al. (10) observed deleterious effects in mice fed heat-polymerized whale oil. Crampton et al. (11) showed impaired weight gain in rats whose diets were high in polymerized oils. They also fractionated the heated oils into six fractions, ranging from straight-chain compounds to cyclic compounds. They observed that the diet containing 20% of the cyclic monomers (non-urea–adducting fraction) caused high mortality in the test rats. The diet containing 20% of the straight-chain compounds did not have any adverse effect on the rats. Raju and Rajagopalan (12) heated sesame, peanut, and coconut oils in open pans at 270°C. The thermal polymers thus produced in the oils caused depressed growth rates in test animals. Kaunitz and co-workers (13) heated lard and cottonseed oils with aeration for 200 h at 95°C. The heated lard contained 17% polymers and the heated cottonseed oil contained 40% polymers. Rats fed the diet containing 20% of these oxidized and polymerized fats suffered from high mortality. Adverse effects were also noted in rats fed diets consisting of 10% of these oxidized and polymerized fats. The adverse trends reversed when the rats were fed diets containing fresh oils. Crampton et al. (14) fed the non-urea adduct–forming components from linseed, soy, and sunflower oils to rats. The fractions from linseed oil had the most deleterious effects on the test rats. The effects from the soybean oil were less pronounced and the sunflower oil had the least effect. Johnson et al. (15) observed that corn oil, thermally oxidized at room temperature, depressed growth in rats. The growth rate became normal once the diet was changed to fresh corn oil. All of the above-mentioned work and the results are summarized in Table 11.1. Subsequent Feeding Studies on Heated Fats Neither commercial fryers nor restaurant fryers are operated under the test conditions discussed in the previous section. These are extreme heating conditions and the results obtained do not represent real-life situations in the frying industry. Melnick


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TABLE 11.1 Early Research on Heated and Oxidized Oils Oil

Parameters

Results

Reference

Lard Sunflower Linseed Soy Cottonseed Rapeseed Peanut Corn Fish Sesame Peanut

20 min at 300°C 30 min at 350°C 6–30 h 275°C

Depressed growth; weight loss Tumors Depressed growth Weight loss Death

(1) (2) (3) (8) (14)

8–12 h at 280°C Open pans at 270°C

Depressed growth; ill health Depressed growth

(4) (12)

(16) called many of these early studies “impractical.” He presented information on used oils gathered from 89 commercial chip-frying operations and indicated that there was little change in the iodine value of the oils as a result of frying, and polymer contents were not an issue. Rice et al. (17) examined fats from restaurants, bakeries, and chip producers. They observed that rats experienced only slight decreases in energy and slight increases in liver size when the diet contained even the most abused oils in this group of products. Alfin-Slater et al. (18) noted that growth, reproduction, lactation, and longevity in rats were not impaired when cottonseed oil was heat-polymerized to effect a drop of 5% of its fresh iodine value. Witting et al. (19) suggested that the incorporation of a single peroxide group into fatty acid molecules was enough to cause toxicity in rats and mice. Nishida et al. (20), on the other hand, reported that the test rats fed heated oils had reduced cholesterol. Perkins and Kummerow (21) heated corn oil for 48 h with agitation. The abused oil was then fractionated via distillation. Weanling rats died within 7 d when they were fed the residue fraction from the non-urea–adducting fatty acids. Alfin-Slater et al. (22) heated various vegetable oils for 60–100 min at 610°F under vacuum. In their feeding studies, no evidence of nutritional impairment was noted, except for soybean oil, which was found to be highly polymerized under the test conditions. A slight decline in digestibility was also observed with this oil. Custot (23) warned that improper frying could severely damage the oils. Keane et al. (24) conducted a study using heated oils from commercial operations. No toxicity was observed in the rats; in fact, those rats fed the heated fats gained weight. The same study reported that oils heated and oxidized under laboratory conditions produced lower growth rates in test rats, but no toxicity was observed in these rats. Rice et al. (25) reported that there was “no reason to believe that fats were nutritionally damaged by normally accepted good practices in present-day food preparation.” They also observed that the frying oils suffered undesirable changes


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in viscosity, browning, and product flavor before the oils reached the state at which biological effects could be observed. They observed biological activity on laboratory rats when they were fed the oil that had been foaming in a potato chip fryer. No specific cause for the foaming was reported. Perkins (26) presented a review of earlier work in the area of frying fat toxicity and posed three questions: (i) Are polymers formed in unsaturated oils during deodorization, processing, and use? (ii) Are polymeric materials absorbed on food products in the fryer; if so, to what extent? (iii) What are the physiologic and nutritional effects of these polymeric materials? The researchers determined that the oil can be polymerized during oil refining if proper precautions are not taken. The polymers are also absorbed by the fried food, but no partitioning effect has been proven. Firestone et al. (27) and Friedman et al. (28) reported that heating cottonseed oil for 190 h at 225°C increased its viscosity. They reported that heating the oils increased viscosity and molecular weight and lowered the iodine value. They observed that rats fed this abused oil suffered from a lack of nutrient absorption. They hypothesized that such abused oils might have interfered with absorption of other nutrients. The forced feeding of urea filtrate monomers and dimers to weanling mice resulted in death. Similar adverse effects were observed when the non-urea–adducting fatty acids were included in the diet. These researchers were the first ones to propose using this class of compounds as an indicator of the quality of heated oils. In 1962, Poling et al. (29) studied the influence of temperature, heating time, and aeration on the nutritive value of heated cottonseed oil. They found that the changes in the oil were proportional to the severity of the conditions. They also reported that the oils with a high level of change were subjected to conditions that were more severe than those encountered in the normal frying process. Test animals had enlarged livers when they were fed damaged oils in their diet. Fleischman et al. (30) recommended against both reusing and overheating oils because these would cause additional hydrolysis and oxidation in the oil. They commented that frying appears to decrease the hypocholesteremic effect of the high concentration of polyenoic acids in raw oils. Raju et al. (31) heated peanut, sesame, and coconut oils in an open iron pan for 8 h at 270°C. Rats fed a diet containing 15% of these oils had reduced growth rates, reduced food intake, increased liver weight, reduced vitamin-B storage, reduced carbohydrate absorption, and higher blood glucose and cholesterol. Perkins and Van Akkeren (32) demonstrated that intermittent heating and cooling of cottonseed oil caused the oil to break down rapidly. Oil heated intermittently for 66 h and oil heated continuously for 166 h contained the same amount of polar materials. They concluded that oils in small operations in which the turnover is low may be damaged more rapidly than those in large operations in which oil turnover is more rapid. This was found to be the case in actual practice. Kaunitz et al. (33) conducted long-term feeding studies in which rats were fed a diet that included up to 30% fat. The fat had been oxidized for 40 h at 60°C, with


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airflow of 1–2 L/min. Cottonseed, chicken fat, beef fat, and olive oils were used. They found that death rates and lesions observed after death were greater in rats that had consumed the oxidized oils, except for the oxidized olive oil. A year later, Kaunitz (34) participated in an IFT-sponsored symposium on the Chemistry and Technology of Deep Fat Frying. In his summary concerning the effects of cooking and storage he noted that: “Intelligent cooking or even storage procedures may improve the quality of some dietary fats.” Nolen et al. (35) conducted a feeding study on rats using hydrogenated soybean oil, cottonseed oil, and lard. These oils were used under restaurant conditions until they were judged to be unfit for use. These fats made up 15% of the diet. The used fats were slightly less absorbable and gave correspondingly slower growth rates. There were no clinical, pathologic, or metabolic criteria to suggest that the used fats adversely affected the population consuming them. Distillable nonurea–adducting fractions from used fats proved somewhat toxic when high concentrations were administered to weanling rats. Their conclusion was: “Although heating of fats under actual frying conditions does cause the formation of substances which can be shown to be toxic, the level of such substances and the degree of their toxicity are so low as to have no practical dietary significance.” Nolen conducted additional studies (36,37) with hydrogenated fats. He concluded that hydrogenated fats, either fresh or used, did not affect reproduction in rats. Poling et al. (38) conducted long-term feeding studies on laboratory rats. The rats were fed heated (182°C for 120 h) cottonseed salad oil, corn oil, lard, and hydrogenated vegetable shortening. They found no significant differences between the heated and unheated oils. They stated that, “The absence of adverse effects attributable to the heated fats during the life span of the rats is further evidence of the safety of these fats of the quality customarily consumed by the human population.” In 1972 and 1973, Ohfuji and his colleagues in Japan conducted a series of studies on the nutritive value of heated oils (39–41). They found a toxic dimer in abused oils, and concluded that this was found in the most polar fraction of the oils. This dimer itself was more digestible than the thermally oxidized oil. The oils were heated for 90 h at 275°C in the presence of air or nitrogen. They did report that they were able to recover small amounts of the dimer in some commercial cooking oils. Billek et al. (42,43) presented their findings on sunflower oil obtained from the commercial production of fish fingers. They isolated different fractions from the oil before and after it had been used for frying, and used these for feeding studies. They found that rats consuming the polar fraction had significantly lower weight gains than the other test animals. As a result of this study, they proposed that the polar fraction could be used as an index of oil quality. They concluded that 30% polar material in fryer oil represented a safe number, a value that was reduced later to 27% for regulatory purposes. This is the non-urea–adducting fraction. This, indeed, was a revival of the work done by Firestone et al. in 1960–1961. Polar materials are, in fact, now used in several European nations as a quality index in


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restaurant fryer oils. At the AOCS meeting in 1978, Clark presented a review on the state of heated oils, reporting that there was no evidence that oils used in commercial operations were abused to the point that they would create health problems. In 1978, Lang et al. (45) published a study based on 10 years of animal feeding studies, in which three generations of rats were fed heated and unheated oils at a level of 10% of their diet. The study concluded, “Frying fats heated under conditions of good commercial practice are not detrimental to the health of test animals.” Billek (46) commented that even after 20 years, the study made by Lang et al. has not been criticized and its conclusions are still valid. Fong et al. (47) used the Ames test (microcosms) as a means of evaluating Chinese peanut oils for aflatoxins. They detected mutagenic activity in fresh oils, an activity that decreased with repeated cooking. This study demonstrated that heating could remove certain undesirable components from fresh oils, i.e., the aflatoxins. Aflatoxins can be present in cold-pressed peanut oil. This is not the case for peanut oil produced in Western countries because the oil is processed at a high temperature. Taylor and his colleagues (48,49) conducted two studies to determine whether mutagens were present in fried foods and the effect of frying conditions on mutagen formation. Their work agreed with that of many others, i.e., mutagens are not a problem if oils are not abused. Goethart et al. (50) conducted a study on frying oils and foods from canteens in The Netherlands and also conducted their own frying studies. Their work indicated that there was a slight decline in weight gain and some differences in liver and kidney size in animals fed more abused oils (frying up to 14 d). They did not find any evidence of mutagens in fried foods or heated oils. Hageman et al. (51–53) also conducted work using the Ames test on heated oils and foods. These workers observed increased mutagenicity in the polar fraction of the oil with increasing abuse. They were unable to isolate the mutagenic components within the polar fraction. In 1990, Addis (54) postulated that cholesterol oxides and other oxidative materials formed as result of heating oil may act as initiators of arterial damage. These materials allegedly damage the arterial walls, setting the stage for plaque deposition. Marquez-Ruiz (55) indicated that thermally oxidized fats might have adverse effects on human health. Industry and Food Service Practices Researchers in the field of nutrition have stated that handling of frying oils under normal operating conditions does not pose any health hazards, even though most fried foods are rich in oil or fat. This was reiterated at the 3rd International Symposium on Frying sponsored by the DGF (56). They made the following statement: “There are no health concerns associated with consumption of frying fats and oils that have not been abused at normal frying conditions.” The next question is whether oil abuse is indeed a problem in the food processing and food service industries. There are a number of studies that indicate that oils used in commercial


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frying are not abused (16,57,58). The oils from these studies did not pose any health concern. When abused, oils break down into hundreds of compounds. Many of these compounds are detrimental to the shelf life of the oils and the products made with them. Complaints from German consumers about fried food quality at restaurants and their aftermath that prompted scientists in that country to initiate studies on fryer oil quality in restaurants, which led to the first recommendations for regulating frying fats (59). Blumenthal (60) evaluated hundreds of oil samples from industrial and food service frying operations and related those samples to actual practices. He found that the oils from the commercial chip fryers were least abused. This is primarily due to high oil-takeout by the food and constant replenishment with fresh oil (Table 11.2). Industrial fryers are used for foods such as French fries and battercoated and breaded products; these are much more abused than the products produced in chip fryers. The fast food, coffee-shop doughnut, and institutional frying operations are the most abusive to frying oil. This agrees with the observations of Perkins and Van Akkeren (32). Table 11.2 compares average values of oil qualities for these industries (60). As noted in Table 11.2, the fast food and restaurant businesses do create abused oils. However, in actual practice, very few restaurant operations allow their oils to reach such high polar concentrations. Trans Fatty Acids Trans fatty acids are the trans isomers of unsaturated fatty acids. Most naturally occurring unsaturated fatty acids are found in the cis form. The cis and trans forms refer to the position of the hydrogen around the double bonds on the fatty acid chain. These hydrogen atoms are held in place at the double bond. When the atoms are on the same geometric side of the chain, they are referred to as being in the cis position; those on opposite sides of the chain are in the trans position. Trans fatty acids, however, are not simply the products of human chemistry. There are several naturally occurring sources of trans acids. They may be found in some plant oils, such as tung and pomegranate oil. However, these are not common edible oils. They are also formed in fats from ruminants, such as cattle and sheep.

TABLE 11.2 Approximate Levels of Polar Materials at Which Various Industry Segments Discard Oila Industry Snack foods Industrial Restaurant and institutional aSource:

Reference 82.


Polars at discard (%) 11–13 15–17 22–27

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The bacteria in the rumen produce trans acids, found in these animals. The levels of trans acids found in natural sources is quite low (1–5% of total fat). If the triglyceride being examined has a high level of trans acids, these will pack together, forming a solid fat. This is a function of the straight chains formed by trans acids. Because they are straight, they will pack more tightly and form crystals or hard fats. Harder fats have higher melting points (Table 11.3). In fact, the melting points of trans acids are midway between those of saturated and the cis unsaturated isomer. The development of the hydrogenation process is credited to a French chemist named Sabatier. The process is now >100 years old. Hydrogenation allows oil refiners to “harden” fats using hydrogen in the presence of a catalyst. The most common catalyst used is nickel. One common misunderstanding is that hydrogenation produces only saturated fats from the unsaturated fats. In fact, a percentage of existing unsaturated fatty acids is converted to both saturated fats and the trans isomers of the naturally occurring cis forms. As described above, the trans isomers have higher melting points than do the original cis isomers, which allows processors to manufacture a variety of plastic fats from the hydrogenated fats. These plastic fats have a wide range of functional characteristics, depending upon their makeup. Over the years, oil refiners have continually refined the hydrogenation process. The makeup of the finished product is a function of the type of processing the oil undergoes. By controlling process time, pressure, temperature, catalyst quality, rate of agitation, and quality of the feedstock and filtration, a range of products may be produced. One of the most critical quality control points is the catalyst. Old or poisoned catalysts produce finished products with higher levels of trans acids. The greater the degree of hydrogenation, the harder the fat. In a fully hydrogenated product, all of the double bonds are eliminated and the resulting product is hard and brittle. Fully hydrogenated oil has essentially zero trans fat content (Table 11.4). Fats and oils are prone to oxidation and other reactions. In particular, soybean and canola oils are susceptible to oxidation. Soybean and canola oils used for frying shelf-stable snacks are typically “brush” or lightly hydrogenated to reduce the linolenic acid content in the oil, which enhances oxidative stability. Oils used for doughnut, food service, or restaurant frying are more heavily hydrogenated. It is logical to ask how much trans fatty acids do people consume and does this pose a potential health risk? It is difficult to determine the consumption of trans fat in TABLE 11.3 Melting Points of C18 Fatty Acids Fatty acid Stearic acid Oleic acid (c i s) Linoleic acid (c i s) Elaidic acid (t r a n s)


Formula

Melting point (°C)

C18:0 C18:1 C18:2 C18:1

69.9 10.0–13.0 –5.0 44.5

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TABLE 11.4 Proportion of Trans Fatty Acids in Food Products Food category Margarine (stick) Margarine (tub) Household salad/cooking oils Household shortenings Foodservice frying fats and oils Baking fats (foodservice) Butter aSource:

Total fatty acids as trans (%) 25–30 13–20 0 14–18 6–40 10–35 2–9

Reference 63.

our daily diet, because the daily diet comprises a very complex mixture of different foods and it varies with individual eating habits. Dr. David Firestone of the United States Food and Drug Administration (FDA) and Dr. W.M.N. Ratnayake (61) showed that there was no single method applicable for all samples. One major barrier to determining the amount of trans fatty acids in the diet is that no one has yet developed a comprehensive database on the subject. As an example, the FDA allows food processors to utilize nutritional databases, such as those in the USDA Handbook 8 series (62), or those developed by suppliers for their products to prepare nutritional labels. The databases listing trans fatty acid contents in various foods are not readily available; thus, anyone who wishes to determine whether their foods contain these materials must have the food analyzed. Dickey and Caughman (63) from the USDA have developed a compilation of fatty acid profiles, including trans acids, for >100 foods, but more work is needed. The amount of trans fatty acids in the daily diet has been a subject of debate for a number of years. In the United States, estimates vary from 7.6 to 15.2 g/d. In 1985, an expert panel report prepared for the FDA (64) estimated daily consumption to be 8.3 g/d. Estimates prepared by the edible oil industry in 1984 and 1989 were 7.6 and 8.1 g/d, respectively. Hunter and Applewhite’s 1986 estimate for daily consumption was 2.3–6.6 (65). Enig et al. (66,67) determined the average daily consumption to be 13.3 g for adolescents and 14.9 g for adults. These latter estimates have been criticized by the edible oil industry as not being realistic based on hydrogenated oil production. There have been reports that in some countries daily consumption of trans fatty acids may be as much as 48 g/d. Even though there is debate over the exact average daily consumption of trans acids, it is clear that there are a number of foods that may have high levels of trans acids. Many of these foods are, unfortunately, common snack foods. Doughnuts contain >30% fat, a third of which is trans fat; this computes to ~5 g of trans fat per doughnut. It is estimated that 10 potato chips, which contain 10 g of total fat, contain 2.2 g of trans fat when they are fried in partially hydrogenated soybean or canola oil.


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The expert panel report from 1985 mentioned above concluded: “The available scientific information suggests little reason for concern with the safety of dietary trans fatty acids at present and expected use levels of linoleic acid.” This report also called for additional studies to clarify certain issues (64). In 1988, the Institute of Shortening and Edible Oils (68) concluded that: “Concerns that have been raised about possible relationships between atherosclerotic disease or cancer are not supported by reliable data.” In their 1994 “Food Fats and Oils” report (69), their position changed somewhat concluding that: “Overall, the data indicate that trans acids behave similarly to saturates with respect to raising plasma cholesterol; however, the extent of cholesterol raising was less than that by saturates.” A 1995 report issued by ILSI (70), the International Life Sciences Institute, concluded that the existing data did not support a link between consumption of trans fatty acids and coronary heart disease. Publications by a number of researchers, especially Hunter and Applewhite (65,71), support the position that there are no health concerns from consumption of hydrogenated fats and oils. On the other hand, a large number of people and organizations indicate that their research data suggest health concerns related to the consumption of trans fatty acids. There is concern that trans fats act more like saturated fats. Table 11.5 presents the time line of health concerns regarding dietary fatty acids. Although the reports that support the safety of hydrogenated fats focus on coronary heart disease, this table indicates that there are other possible health concerns. A 1994 report by the Danish Nutrition Council (72) concluded that, “Trans fatty acids TABLE 11.5 Time Line of Concerns About Health Issues Regarding Dietary Trans Fatty Acidsa,b Date

Researcher

Concerns expressed

1956 1958 1970s 1970s 1977 1978 1980s 1989 1990s

H. Sinclair A. Keys W.E. Connor and others F.A. Kummerow G.V. Mann M.G. Enig University of Maryland Enig, Teter, and Barnard T. Hamis et al. Mensink and Katan

1990s

B. Koletzko

1993–94

Harvard University Willet et al. G.V. Mann

Increased cancer EFA deficiency Increased heart disease Adverse effect on serum cholesterol Adverse effect on serum cholesterol Increased heart disease Increased cancer mortality Altered mixed function oxidase enzymes; milk fat depression; decreased insulin binding Decreased testosterone, abnormal sperm Adverse effect on CHD risks; total cholesterol; LDL-C; HDL-C; LP(a) Low birth weight infants, altered n-3 EFA status Increased heart disease, increased cancer risk

1994 aSource:

Increased heart disease

Reference 83.

bAbbreviations: EFA, essential

fatty acids; CHD, coronary heart disease; LDL-C, low density lipoprotein cholesterol; HDL-C, high density lipoprotein cholesterol; LP(a), lipoprotein a.


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increase the likelihood of developing atherosclerosis and possibly have a harmful effect on the growth of the fetus.” As a result of this study, the Danish Council requested a reduction in trans fatty acid content of foods. The continuing research of the Dutch workers, Mensink (73,74) and Katan (75,76), and of the German researcher, Koletzko (77,78), all of whom have indicated that trans fats increase health risk suggests that the effect of trans fatty acid on human health requires further clarification. The American Council on Science and Health (79) has made one of the best and most objective overviews of the trans fatty acid situation on science and health. Their report indicates that consumption of trans acids has an adverse effect on blood lipoproteins compared with unmodified vegetable oils. They indicate that more work is required to compare trans and saturated fats, and that studies on populations that have linked high intakes of trans fats with heart disease have had weaknesses in their methodology. One wonders what the future will hold for hydrogenated fats and oils. These fats offer a wide range of functions useful for the processing industry, especially the baking industry. The alternative to using hydrogenated fats would be to return to using animal fats or the so-called tropical oils, something that is not likely to happen. The American Council on Science and Health suggests using less fat and a more intelligent selection of types of foods, which is a good common sense recommendation no matter what one’s diet (79). It is likely that there will be some changes in foodservice frying fats and maybe even industrial oils. These products are highly hydrogenated for stability and extended fry life. Even though members of the edible oil industry defend hydrogenation, they are cognizant of the increasing consumer awareness of trans fats and are looking for alternatives. An example of an alternative product is one created by Cargill Specialty Oils. In 1998, they released a line of no or low trans-fatty acid products, and used the no-trans feature as a tool for marketing the products as healthy oils. According to Cargill spokespeople, “We now have a line of oils which fit the all-natural definition and have no hydrogenation required so they’re a healthier alternative without any compromise on flavor or shelf-life stability.” Environmental Concerns There are literally thousands of compounds formed in the oil during deep-frying of foods. Fritsch (57) summarized the many classes of materials that are formed during frying. A fryer has been compared to a large steam distillation apparatus. As the water in food boils off, the steam removes volatile compounds from the oil. At one time, these went up the stack and into the environment, but today, these volatile materials are either trapped in a spray tower or burned as fuel. One of the volatile degradation products of deep-fat frying is a mutagenic compound, called acrolein, also known as acrylaldehyde, acrylic aldehyde, and 2propenal. This compound is a clear or yellow compound with a disagreeable odor. The presence of blue smoke indicates that the oil is degrading and that acrolein


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may be released. It vaporizes much more easily than water. The chemical formula is: H2C=CH-CHO. Small amounts of acrolein may be found in fried foods and cooking oils. Acrolein that is inhaled will leave the body within minutes. As with any compound, the effects on health vary with the amount and length of exposure. Short exposures to low levels of the compound may cause eye watering and throat irritation and soreness. Acrolein exposure at 170–430 ppb will result in irritation. These effects disappear within minutes after the exposure stops. Higher levels of the compound and longer exposure times may affect the lungs so severely that death could result. There is no available information on the effects of consuming foods or beverages containing acrolein. The Occupational Safety and Health Administration (OSHA) has established limits for acrolein of 0.1 ppm (100 ppb) in workroom air to protect workers during an 8-h workday over a 40-h work week. NIOSH (National Institute for Occupational Safety and Health) recommends that the concentration in workroom air be limited to 0.1 ppm averaged over an 8-h shift (Table 11.6). TABLE 11.6 Health Effects from Breathing Acrolein Short-term exposure (1 4 d) Levels in air (ppm)

Length of exposure (min)

0.00005 0.17 0.26 0.43

Description of effects Minimum risk level Eye irritation Nose irritation Throat irritation

40 40 40

Long-term exposure (1 4 d) Levels in air (ppm)

Length of exposure (min)

0.00009 xxx

xxx xxx

Description of effects Minimum risk level based on animal studies The health effects of long term exposure to humans to air containing specific levels of acrolein are not known

Exposure to acrolein Concentration (ppm)

Effects

1.0–2.3 1.2 0.8–0.9

Medium to severe eye irritation in 5 minutes Extremely irritating to all mucous membranes within 5 min; lacrimation Changes in amplitude of respiratory membranes; slightly increased respiratory frequency; decreased eye sensitivity to light; changes in optical chronaxy Slight eye and nose irritation; no effect on respiratory frequency or amplitude; odor perceived 30% felt eye irritation in 2 min; increased annoyance and no eye or nose irritation during repeated exposure Odor threshold for most acrolein sensitive people Threshold for affecting electrocortical activity

0.3–0.5 0.14–0.15 0.03–0.034 0.02 aSource:

Reference 84.


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Some scientists have theorized that this compound may have had several insidious effects on the industry, particularly fast food and restaurant operations. Dr. Michael Blumenthal (personal communication) suggested that acrolein in the work environment has contributed in part to the rapid turnover in that industry. This may be true, although the work environment itself in a fast food restaurant is a large factor in the high turnover rate among workers. At an IFT short course in 1994, Eskin (80) addressed the acrolein issue at length. He presented materials relating to cancer risk in Chinese women and cooking with oil. Because acrolein is a prime degradation compound, the implication was that it could be a contributor to the development of the disease. This is supported by a recent publication by Chinese scientists who isolated a series of mutagens from fumes of peanut oil used for cooking. The issue of heated fats and public health has not been a focus in the United States, but as noted earlier, this is an issue in Europe. Firestone et al. (81) first presented a review of the regulatory situation pertaining to heated fats and oils at the 1990 meeting of the Institute of Food Technologists. In that publication, it was noted that Belgium, France, Germany, Spain, and Switzerland were among the countries who had established regulatory limits for polar materials in restaurant frying oils, the segment most likely to abuse oil in the restaurants. It was, in fact, abuse of frying fats at the restaurant level that led to the studies that resulted in the recommendations to establish regulatory limits for frying fats and oils. Ironically, Germany, where this work was done, has not established regulations on the national level, but only in its individual states. Since that time, other EU nations have followed the Germans in establishing regulatory limits for restaurant oils. These guidelines and regulations are presented in Table 11.7.

Summary The basic belief in the scientific community is that heated oils, particularly those that have not been abused, are not a health hazard. Some compounds found in abused oils are potential mutagens, but the levels at which they are found are low, and the consequent health effect is considered to be small. Test animals fed large quantities of abused oil or fractions tend to gain weight at a slower rate than those given fresh or less abused oils, apparently due to the indigestible compounds (polymers) formed in the fryer oil. Other studies using these same badly abused oils have even resulted in the development of tumors or worse in test animals. Conversely, other studies have shown that slightly heated oils are more digestible than fresh oils. When conducting animal feeding studies using heated oils, it was shown that it is essential to ensure that diets are balanced so that the actual effects of the oils may be observed. Some of the early work has been questioned because of this exact point. The most deleterious compounds were found in the non-urea–adducting fraction of abused oils, which contains highly polar materials. As early as 1961, polar


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compounds were proposed as an index for oil quality and safety for fryer oils. A 30% limit was recommended. Many years after this initial recommendation, the enactment of regulations or guidelines in several European nations has occurred, targeted at ensuring the production of safe and wholesome foods in the restaurant and food service industries. This discard point for polar materials generally coincides with the best practices of cooks in restaurants in the United States. The basic message to users of frying fats was clearly stated in the DGF recommendations of 2000. To ensure that there are no health concerns, it is essential that the quality of frying oil be controlled. If oil quality is allowed to degrade, health concerns are only part of the issue. In a cost-conscious world, the real issue is economics. The use of abused oil for frying produces poor quality food. Consumers may reject such food because of poor flavor. Because the food industry relies on repeat business, such actions may result in a long-term loss of business for the operation. References 1. Morris, H.P., C.D. Lassen, and J.W. Lippincott, Effects of Feeding Heated Lard to Rats. Histological Description of Lesions Produced, J. Natl. Cancer Inst. 4:285 (1943). 2. Roffo, A.H., (1938) The Carcinogenic Action of Oxidized Vegetable Oils, Biol. Inst. Med. Exp. 21:1–134. 3. Crampton, E.W., and J. Millar, Studies on the Utilization of Different Types of Shortening—Linseed Oil, Rapeseed Oil, Lard, and Commercially Prepared Peanut Oil, unpublished data cited from Crampton et al. 1951. 4. Harris, P., unpublished data cited from Crampton et al. 1951, (1947). 5. Lane, A., D. Blickenstall, and A.C. Ivy, (1950) The Carcinogenicity of Fat Browned by Heating, Cancer 3:1044–1051. 6. Lassen, S., E.K. Bacon, and H.J. Dunn, The Digestibility of Polymerized Oils, Arch. Biochem. 23:1–7 (1949). 7. Crampton, E.W., R.H. Common, F.A. Farmer, F.M. Berryhill, and L. Wiseblatt, Studies to Determine the Nature of the Nutritional Value of Some Vegetable Oils by Heat Treatment, J. Nutr. 44:177–189 (1951). 8. Crampton, E.W., F.A. Farmer, and F.M. Berryhill, The Effect of Heat Treatment on the Nutritional Value of Some Vegetable Oils, J. Nutr. 43:431–440 (1951). 9. Deuel, H.J., S.M.Greenberg, C.E. Calbert, R. Baker, and H.R. Fisher, Toxicological Studies on Isopropyl and Stearyl Citrates, Food Res. 16:258–280 (1951). 10. Frahm, H., A. Lembke, and G. Von Rappard, The Suitability of Polymerized Oil for Human Nutrition, Michwirtsch. Forschungsber. 4:443 [cited from Crampton et al. 1956] (1953). 11. Crampton, E.W., R.H. Common, F.A. Farmer, A.F. Wells, and D. Crawford, Studies to Determine the Nature of the Damage to the Nutritive Value of Some Vegetable Oils from Heat Treatment, J. Nutr. 49:333–346 (1953). 12. Raju, N.V. and R. Ragopalan, Nutritive Value of Heated Vegetable Oils, Nature 176: 513–514 (1955). 13. Kaunitz, H., C.A. Slanetz, R.E. Johnson, H.B. Knight, D.H. Saunders, and D. Swern, Biological Effects of the Polymeric Residues Isolated from Oxidized Fats, J. Am. Oil Chem. Soc. 33:630–634 (1956).


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14. Crampton, E.W., R.H. Common, E.T. Pritchard, and F.A. Farmer, Studies to Determine the Damage to the Nutritive Value of Some Vegetable Oils from Heat Treatment, J. Nutr. 60:1, 13–24 (1956). 15. Johnson, O.C., T. Sakaragi, and F.A. Kummerow, A Comparative Study of the Nutritive Value of Thermally Oxidized Oils, J. Am. Oil Chem. Soc. 33:433–435 (1956). 16. Melnick, D. (1957) Nutritional Quality of Frying Fats in Commercial Use, J. Am. Oil Chem. Soc. 34:578–582 (1957). 17. Rice, E.E., P.E. Mone, and C.E. Poling, The Effects of Commercial Frying on the Nutritive Value of Fats, Fed. Proc. 16:398 (1957). 18. Alfin-Slater, R.B., A.F. Wells, L. Aftergood, and H.J. Deuel, Nutritive Value and Safety of Hydrogenated Vegetable Fats as Evaluated by Long-Term Feeding Studies with Rats, J. Nutr. 63 (1957). 19. Witting, L.A., T. Nishida, O.C. Johnson, and F.A. Kummerow, The Relationship of Pyridoxine and Riboflavin to the Nutritional Value of Polymerized Fats, J. Am. Oil Chem. Soc. 34:421–424 (1957). 20. Nishida, T., F. Takenaka, and F.A. Kummerow, Circ. Res. 6:194 (1958). 21. Perkins, E.G., and F.A. Kummerow, The Nutritional Effects of Polymers Isolated from Thermally Oxidized Corn Oil, J. Nutr. 68:101–109 (1959). 22. Alfin-Slater, R.B., S. Auerbach, and L. Aftergood, Nutritional Evaluation of Some Heated Oils, J. Am. Oil Chem. Soc. 36:638–641 (1959). 23. Custot, F., Toxicity of Heated Fats. The Problem of Frying Oils, Ann. Nutr. Aliment. 13:417 (1959). 24. Keane, K.W., G.A. Jacobsen, and C.H. Krieger, Biological and Chemical Studies on Commercial Frying Oils, J. Nutr. 68:57–74 (1959). 25. Rice, E.E., C.E. Poling, P.E. Mone, and W.D. Warner, A Nutritive Evaluation of OverHeated Fats, J. Am. Oil Chem. Soc. 37:607–613 (1960). 26. Perkins, E.G., Nutritional and Chemical Changes Occurring in Heated Fats: A Review, Food Technol. 14:508–514 (1960). 27. Firestone, D., W. Horwitz, L. Friedman, and G.M. Shue, Heated Fats. I. Studies of the Effects of Heating on the Chemical Nature of Cottonseed Oil, J. Am. Oil Chem. Soc. 38:253–257 (1961). 28. Friedman, L., W. Horwitz, G.M. Shue, and D. Firestone, Heated Fats. II. The Nutritive Properties of Heated Cottonseed Oil and of Heated Cottonseed Oil Fractions Obtained by Distillation and Urea Adduct Formation, J. Nutr. 73:85–93 (1961). 29. Poling, C.E., W.D. Warner, P.E. Mone, and E.E. Rice, The Influence of Temperature, Heating Time, and Aeration upon Nutritive Value of Fats, J. Am. Oil Chem. Soc. 39:315 (1962). 30. Fleischman, A.I., A. Florin, J. Fitzgerald, A.B. Caldwell, and G. Eastwood, Studies on Cooking Fats and Oils, J. Am. Diet. Assoc. 42:394–398 (1963). 31. Raju, N.V., M.N. Rao, and R. Rajagopalan, Nutritive Value of Heated Vegetable Oils, J. Am. Oil Chem. Soc. 42:774–776 (1965). 32. Perkins, E.G., and L.A. Van Akkeren, (1965) Heated Fats. IV. Chemical Changes in Fats Subjected to Deep Fat Frying Processes, J. Am. Oil Chem. Soc. 42:782–786. 33. Kaunitz, H., R.E. Johnson, and L. Pegus, A Long-Term Nutritional Study with Fresh and Mildly Oxidized Vegetable and Animal Fats, J. Am. Oil Chem. Soc. 42:770–774 (1965). 34. Kaunitz, H., Nutritional Aspects of Thermally Oxidized Fats and Oils, Food Technol. 21:278–281 (1967).


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35. Nolen, G.A., J.C. Alexander, and N.R. Artman, Long-Term Rat Feeding Study with Used Frying Fats, J. Nutr. 93:337–348 (1967). 36. Nolen, G.A., Effects of Fresh and Used Hydrogenated Soybean Oil on Reproduction and Teratology in Rats, J. Am. Oil Chem. Soc. 49:688–693 (1972). 37. Nolen, G.A., A Feeding Study of a Used, Partially Hydrogenated Soybean Oil, Frying Fat in Dogs, J. Nutr. 103:1248–1255 (1973). 38. Poling, C.E., E. Eagle, E.E. Rice, A.M.A. Durand, and M. Fisher, Long-Term Responses of Rats to Heat-Treated Dietary Fats: IV. Weight Gains, Food and Energy Efficiencies, Longevity, and Histopathology, Lipids 5:128–136 (1970). 39. Ohfuji, T., and T. Kaneda, Characterization of the Toxic Compounds in Thermally Oxidized Oil, Lipids 8:353–359 (1973). 40. Ohfuji, T., H. Igarashi, and T. Kaneda, Studies on the Relationship Between the Nutritive Value and the Structure of Polymerized Oils. VIII. Presence of Toxic Dimer Glycerides in Used Frying Oils, Yakagaku 21:21 (1972). 41. Ohfuji, T., K. Sakurai, and T. Kaneda, Studies on the Relationship Between Nutritive Value and the Structure of Polymerized Oils. VII. Absorption and Metabolism of the Toxic Substance Separated from Thermally Oxidized Oil in Rats, Yakagaku 21:68 (1972). 42. Billek, G., G. Guhr, and W. Sterner, presented at 69th Annual Meeting of the American Oil Chemists’ Society, New York, NY, 1977. 43. Billek, G., G. Guhr, and W. Sterner, Feeding Experiments with Heated Fats and Fat Fractions, Fette Seifen Anstrichm. 81:562–566 (1979). 44. Clark, W., Nutritional Aspects of Frying Fats—An Overview, presented at the 70th Annual Meeting of the AOCS, Chicago, Illinois, 1978. 45. Lang, K., G. Billek, J. Führ, J. Henschel, E. von Jan, J. Kracht, H. Scharmann, H.-J. Strauss, M. Unbehend, and J. Waibel, Ernährungsphysiologische Eigenschaften von Fritierfetten. U. Ernährungswiss. Supplement 21:1–61 (1978). 46. Billek, G. Eur. J. Lipid Sci. and Tech.: Special Edition, 102:8–9, 587–593 (2000). 47. Fong, L.Y.Y., C.C.T. Ton, P. Koonanuwatchaidet, and D.P. Huang, Mutagenicity of Peanut Oils and Effect of Repeated Cooking, Food Cosmet. Toxicol. 18:467–470 (1980). 48. Taylor, S.M., C.M. Berg, N.H. Shoptaugh, and V.N. Scott, Lack of Mutagens in DeepFat Fried Foods Obtained at the Retail Level, Food Chem. Toxicol. 20:209–212 (1982). 49. Taylor, S.M., C.M. Berg, N.H. Shoptaugh, and E. Traisman, Mutagen Formation in Deep-Fat Fried Foods as a Function of Frying Conditions, J. Am. Oil Chem. Soc. 60: 576– 580 (1983). 50. Goethart, R.L.D., H. Hoekman, E.J. Sinkeldam, L.J. Van Gamert, and R.J.J. Hermus, Cooking in Oil: The Stability of Frying Oils with a High Linoleic Acid Content, Voeding 46:300–306 (1985). 51. Hageman, G., R. Kikken, F. ten Hoor, and J. Kleinjans, Assessment of Mutagenic Activity of Repeatedly Used Frying Fats, Mutat. Res. 204:593–604 (1988). 52. Hageman, G., R. Kikken, F. ten Hoor, and J. Kleinjans, Linoleic Acid Hydroperoxide Concentration in Relation to Mutagenicity of Repeatedly Used Deep Frying Fats, Lipids 24:899–902 (1989). 53. Hageman, G., R. Hermans, F. ten Hoor, and J. Kleinjans, Mutagenicity of Deep Frying Fat, and Evaluation of Urine Mutagenicity in Man After Consumption of Fried Potatoes, Food Chem. Toxicol. 28:75–80 (1990). 54. Addis, P.B., Coronary Heart Disease: An Update with Emphasis on Dietary Lipid Oxidation Products, Nutr. News 62:7–10 (1990).


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55. Marquez-Ruiz, G., and Dobarganes, M.C., Nutritional and Physiological Effects of Used Frying Fats, in Deep Frying: Chemical, Nutrition and Practical Applications, edited by E.G. Perkins and M.D. Erickson, AOCS Press, Champaign, IL, 1996. 56. DGF, Recommendations of the 3rd International Symposium on Deep Fat Frying— Optimal Operation, Eur. J. Lipid Sci. Technol. 102:594 (2000). 57. Fritsch, C.W., Measurements of Frying Fat Deterioration, J. Am. Oil Chem. Soc. 58:272 (1981). 58. Blumenthal, M.M., Optimum Frying: Theory and Practice, Libra Laboratories, Piscataway, NJ, 1987. 59. DGF, Meeting Summary: German Society for Fat Research, Fette Seifen Anstrichm. 75:49 (1973). 60. Blumenthal, M.M., A New Look at the Chemistry and Physics of Deep Fat Frying, Food Technol. 45:68–71, 94 (1990). 61. Ratnayake, W.M., Determination of Trans Unsaturation by Infrared Spectroscopy and Determination of Fatty Acid Composition of Partially Hydrogenated Vegetable Oils and Animal Fats by Gas Chromatography/Infrared Spectrophotometry: Collaborative Study, J. Assoc. Off. Anal. Chem. 78:703–802 (1995). 62. USDA, Composition of Foods: Agriculture Handbook No. 8, Agriculture Research Service, United States Department of Agriculture, Superintendent of Documents, 1975. 63. Dickey, L.E., and Caughman, C.R., Fatty Acid Profiles Including Trans Isomers in 123 Food Sources Presented as Grams of Fatty Acid per 100 Grams of Foods, 1995. 64. United States Food and Drug Administration (1985) 65. Hunter, J.E., and T.H. Applewhite, Isomeric Fatty Acids in the U.S. Diet: Levels and Health Perspectives, Am. J. Clin. Nutr. 44:707–717 (1986). 66. Enig, M.G., S, Atal, J. Sampugna, and M. Keeney, Trans Fatty Acids in the U.S. Diet, J. Am. Coll. Nutr. 9:471–521 (1990). 67. Enig, M.G., S. Atal, J. Sampugna, and M. Keeney, Responses to Letters to the Editor, J. Am. Coll. Nutr. 10:512–514, 517–518, 519–521 (1991). 68. Anonymous, Food Fats and Oils, 7th edn., Institute of Shortening and Edible Oils, New York, NY, 1994. 69. Anonymous, Food Fats and Oils, 6th edn., Institute of Shortening and Edible Oils, New York, NY, 1988. 70. International Life Sciences Institute (ILSI) Expert panel on Trans Fatty Acids and Coronary Heart Disease, Trans Fatty Acids and Coronary Heart Disease, edited by P.M. Kris-Etherton, Am. J. Clin. Nutr. 62:518–519 (1995). 71. Hunter, J.E., and T.H. Applewhite (1991). 72. Danish Nutrition Council Task Group, The Influence on Health of Trans Fatty Acids, Transfedtsyers Betydning for Sundheden (1994); Danish Nutrition Council, Trans Fatty Acids, Clin. Sci. 88:375–392 (1995). 73. Mensink, R.P., and G. Hornstra, The Proportion of Trans Monounsaturated Trans Fatty Acids in Serum Triacylglycerols or Platelet Phospholipids as Objective Indicator of Their Short-Term Intake in Healthy Men, Br. J. Nutr. 73:605–612 (1995). 74. Mensink, R.P., Summary Statement: Isomeric Fatty Acids, World Rev. Nutr. Diet. 75:173–174 (1994). 75. Katan, M.B., Commentary on the Supplement Trans Fatty Acids and Coronary Heart Risk, Am. J. Clin. Nutr. 62:518–519 (1995). 76. Katan, M.B., Exit Trans Fatty Acids, Lancet 346:1245–1246 (1995).


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77. Koletzko, B., and T. Decsi, Adipose Tissue Trans Fatty Acids and Coronary Heart Disease, Lancet 345:273–278 (1995). 78. Koletzko, B., Trans Fatty Acids and the Human Infant, World Rev. Nutr. Diet. 75:82–85 (1994). 79. Meister, K., Facts About Fats: Health Effects of Dietary Fats and Oils, American Council on Science and Health, New York, NY, 1995. 80. Eskin, N.A.M., Toxicological Concerns with Frying Fats and Oils, presented at IFT sponsored short course, Understanding Deep Frying of Foods, Atlanta, Georgia, June 24–25, 1994. 81. Firestone, D.D., R.F. Stier, and M.M. Blumenthal, Regulation of Frying Fats and Oils, Food Technol. 45:90–94 (1990). 82. Stier, R.F., and M.M. Blumenthal, Multifunctional Fats & Oils, Baking & Snack 13:29 (1991). 83. Enig, M.G., Trans Fatty Acids in the Food Supply, Enig & Associates, Silver Spring, MD, 1995. 84. Beauchamp, R.O., Jr., D.A. Andjelkovich, A.D. Kligerman, K.T. Morgan, and H. Heck, A Critical Review of the Literature on Acrolein Toxicity, CRC Crit. Rev. Toxicol. 14:309 (1985).

Suggested Reading Allen, R.R., Hydrogenation, J. Am. Oil Chem. Soc. 58:166–169 (1981). Anonymous, Fat Trans-Formation, Snack Food & Wholesale Bakery, December 4, 1988. Blumenthal, M.M., Presented at IFT Sponsored Short Course, Understanding Deep Frying of Foods, Atlanta, Georgia, June 24–25, 1994. Brooks, D., Some Perspectives on Deep-Fat Frying, INFORM 2:1091–1095 (1991). Brown, M.H., Here’s the Beef: Fast Foods Are Hazardous to Your Health, Sci. Dig.:31–36, 76–77 (April, 1986). Buxtorf, U.P., W. Manz, and M. Schupbach, Gebiete Lebensm. Hyg. 67:429 (1976). Castang, J. Ann. Fals. Exp. Chim. 74:701 (1981). Chang, S.S., R.J. Peterson, and C.T. Ho, Chemical Reactions Involved in Deep Fat Frying of Food, J. Am. Oil Chem. Soc. 55:718 (1979). Clark, W.L., and G.W. Serbia, Safety Aspects of Frying Fats and Oils, Food Technol. 45:84–86 (1991). Dickey, L.E., Trans Fatty Acid Content of Selected Foods, INFORM 6:484 (1995). Firestone, D., Worldwide Regulation of Frying Fats, INFORM 4:1366–1371 (1993). Gao, Y.-T, W.J. Blot, W. Zheng, A.G. Ershow, C.W. Hsu, L.I. Levin, R. Zhang, and J.F. Frameni, Jr., Lung Cancer Among Chinese Women, Int. J. Cancer 40:604–609 (1987). Gertz, C., Analytical Aspects and Possibilities of the Development of Acrylamide in Fried Foods, Eur. J. Lipid Sci. Technol. 104:762–771 (2002). Guhr, G., and J. Waibel, Untersuchung an Friterfetten: Zusammenhange Zwischen dem Gehalt an Petrolather—Unloslichen Oxidierten Fettsauren und dem Gehalt an Polaren Substanzen bzw. dem Gehalt an Polymeren Triglyceriden, Fette Seifen Anstrichm. 80:106 (1978). Hayes, K.C., Designing a Cholesterol-Removed Fat Blend for Frying and Baking, Food Technol. 50:92–97 (1996).


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Jones, L.A., and C.C. King, Cottonseed Oil, National Cottonseed Products Association and Cotton Foundation, Memphis, TN, 1990. Kamal-Eldin, A., L.A. Appelqvist, C. Gertz, and F.R. Stier (1996) Enhancing the Frying Performance of High Oleic Sunflower Oil Using a Specially Manufactured Sesame and Rice Bran Oil, presented at the Annual Meeting of the AOCS, Indianapolis, IN. Kochkar, S.P., Stabilisation of Frying Oils with Natural Antioxidant Components, Eur. J. Lipid Sci. Technol. 102:552–559 (2000). Mankel, A., Zur Analytik und Beurteilung von Fritürenfetten II. Fette Seifen Anstrichm. 72:677–688 (1970). Marquez-Ruiz, G., M.C. Perez-Camino, and M.C. Dobarganes, J. Am. Oil Chem. Soc. 69: 930 (1992). Melton, S.L., Nutritional Needs for Fat and the Role of Fat in the Diet, in Deep Frying: Chemical, Nutrition and Practical Applications, edited by E.G. Perkins and M.D. Erickson, AOCS Press, Champaign, IL, 1996. Potter, N.N., Food Science, 2nd edn., AVI Publishing, Westport, CT (1973). Silkeberg, A., Stable Oil Composition, U.S. Patent Pending (1996). Stevenson, S.G., M. Vaisey-Genser, and N.A.M. Eskin, (1984) Quality Control in the Use of Deep Frying Oils, J. Am. Oil Chem. Soc. 61:1102. Stier, R.F., The Functions of Trans Fatty Acids, Baking & Snack 19:78–86 (1997). Tareke, E., P. Rydberg, P. Karlsson, S. Eriksson, and Tornqvist, Analysis of Acrylamide, A Carcinogen Formed in Heated Foodstuffs, J. Agric. Food Chem. 50:4998–5006 (2002). Thompson, J.A., M.M. Paulose, B.R. Reddy, R.G. Krishnamurthy, and S.S. Chang, A Limited Survey of Fats and Oils Used for Deep Fat Frying, Food Technol. 21:405–412 (1967). United States Food and Drug Administration, FDA Proposes New Rules for Trans Fatty Acids in Nutritional Labeling, Nutrient Content Claims and Health Claims, HHS News, November 12, 1999. United States Food and Drug Administration, Detection and Quantitation of Acrylamide in Foods Draft Method, United States Food and Drug Administration, Center for Food Safety and Applied Nutrition, July 23, 2002. United States Food and Drug Administration, FDA Draft Plan for Acrylamide in Food, United States Food and Drug Administration, Center for Food Safety and Applied Nutrition, September 20, 2002. United States Food and Drug Administration, Food Labeling: Trans Fatty Acids in Nutrition Labeling and Nutrition Content Claims, Fed. Regist. 63:216, p. 61711, November 9, 1998. Wolfram, G., Recent Findings on Nutritional Properties of Heated Fats—A General Review, Fette Seifen Anstrichm. 81:559–562 (1979). Wu, S.-C., G.-C.Yen, and F. Sheu, Mutagenicity and Identification of Mutagenic Compounds of Fumes Obtained from Heated Peanut Oil, J. Food Protect. 64:240–245 (2001).


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Chapter 12

Regulatory Requirements for the Frying Industry David Firestone Food and Drug Administration, Washington, DC 20204

Introduction Improper frying operations result in degradation of frying fats and diminish the quality and wholesomeness of fried food. Although there are no worldwide regulations and guidelines for control of frying fats and frying operations, a number of European countries, concerned with the quality of fried foods and possible health risks to consumers, have issued regulations and guidelines for control of frying fats and frying operations (1,2). State and local agencies in the United States as well as the Food and Drug Administration (FDA) have not promulgated specific regulations or guidelines controlling the quality of frying fats because it has not been determined that frying fats used in the preparation of fried foods are injurious to health. However, the Department of Agriculture's Food Safety and Inspection Service (USDA/FSIS) Meat and Poultry Inspection Manual contains several general guidelines for frying meat and poultry products (3), and the agency has issued a plant sanitation directive requiring cleaning of frying equipment at regular intervals (4). Safety and other aspects of frying technology have been discussed at symposia of the Institute of Food Technologists and German Society for Fat Science (Deutsche Gesellschaft für Fettwissenschaft, DGF) (5–8). Quality Control After the 1979 symposium on frying fats and oils (6), the DGF recommended that total polar compounds be determined to complement traditional organoleptic (sensory) evaluation of frying fat quality. This method (9), involving silica gel column chromatography, became a standard reference method in many European countries concerned with possible health risks from improper use of frying fats. Determination of polymerized (dimeric and polymeric) triglycerides by gel permeation (size exclusion) high-pressure liquid chromatography (HPLC) (10) is also used widely for the control of frying fat quality. Many analytical tests have been proposed for evaluation of frying fat quality (Table 12.1). Quick tests are also available for carrying out in situ evaluations at the fryer. These include the Oxifrit Test (redox indicator) and the Fritest (carbonyl compounds) distributed by E. Merck (Darmstadt, Germany), and the Veri-Fry quick tests available from Libra Laboratories (Metuchen, NJ).


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TABLE 12.1 Laboratory Tests for Oil Quality Determination Acid value Anisidine value Carbonyl value Color Cyclic fatty acids Dielectric constant Conjugated diene value aTBA,

Epoxides Fatty acid composition Free fatty acids Iodine value Peroxide value Polymeric triglycerides

Refractive index Smoke point TBA testa Total polar compounds Trans fatty acids Viscosity Total volatiles

thiobarbituric acid.

FDA Regulations The FDA has not established specific regulations to control the quality of frying fats. However, frying fats are regulated by the general provisions of the Federal Food, Drug, and Cosmetic Act, which states that a food is deemed adulterated if it “contains any poisonous or deleterious substance which may render it injurious to health” [sec. 402 (a)(1)], if it contains “any added poisonous or added deleterious substance (other than specified substances such as pesticides” [402 (a)(2)], if it “consists in whole or in part of any filthy, putrid or decomposed substance, or if it is otherwise unfit for food” [sec. 402 (a)(3)], or if it “has been prepared, packed or held under insanitary conditions whereby it may have been contaminated with filth, or whereby it may have been rendered injurious to health” [402 (a)(4)]. Also, section 404 of the Act mandates the Secretary of Health and Human Services to promulgate regulations to control contamination of food with microorganisms during the manufacture, processing, or packing of food products distributed in interstate commerce. Concerned about food safety, the FDA has been leading an effort in the United States to improve coordination among public health and food regulatory officials to improve food safety programs to minimize outbreaks of foodborne illness (11,12). This effort has included programs to apply Hazard Analysis and Critical Control Point (HACCP) plans to food preparation facilities as well as the establishment of a national database on the occurrence of food-borne disease risk factors within the retail segment of the food industry, which included improper handling of food and poor sanitation (13). Five practices and behaviors were noted that resulted in the most significant “out of compliance” rate: 1. Cold holding of potentially hazardous food (PHF) at ≤5°C. 2. Ready-to-eat (RTE), PHF cold holding at ≤5°C. 3. Commercially processed RTE, PHF date marked. 4. Surfaces/utensils cleaned/sanitized. 5. Proper, adequate hand washing.


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In addition, a set of procedures were developed for standardizing and certifying retail food inspection and training officers to ensure that retail foods are safe, unadulterated, and honestly presented to the consumer (14). FDA programs to reduce food-borne illness, encourage voluntary HACCP-based efforts from industry, and standardize food inspection procedures include use of the Food Code (15) as a general reference document by state and local government agencies responsible for overseeing food safety in retail establishments. Although the Food Code is neither federal law nor federal regulation, it represents the FDA’s best advice for a uniform system of regulation to ensure that food at retail is safe. The various sections of the Food Code cover employee health; personal cleanliness and hygiene practices; food handling, preparation, and presentation; equipment installation, use, and sanitation; water plumbing and waste handling; physical facilities; storage and use of toxic materials (e.g., sanitizers, drying agents, pesticides, fruit and vegetable washing chemicals); and compliance and enforcement procedures including approval of HACCP plans. Section 3–401.11 of the Food Code specifies that all parts of a food be heated to minimum temperatures and holding times to ensure that the foods are safe. Section 4–301.14 states that ventilation hood systems should be sufficient in number and capacity to prevent grease or condensation from collecting on walls and ceilings. Section 6–202.12 states that heating, ventilating, and air conditioning systems should be designed and installed so that make-up air intake and exhaust vents do not cause contamination of food, food-contact surfaces, equipment, or utensils. An Annex specifies a series of enforcement mechanisms and references including management and personnel guidelines for ensuring food safety, food establishment inspection, and preparation of inspection reports; HACCP guidelines including procedures to ensure that HACCP systems are working, plus typical flow diagrams; food processing requirements; and a set of model forms and guides including HACCP guidelines and HACCP Food Inspection Report forms. The Food Code does not specifically specify optimum frying temperatures because it is concerned primarily with the destruction of microorganisms that cause food-borne illness. However, the Food Code specifies that all parts of a food be heated to 63°C for 3 min (minimum) and for longer holding times at lower temperatures (121 min at 54°C). In 1998, FDA drafted a document “Managing Food Safety: A HACCP Principles Guide for Operators of Food Establishments at the Retail Level” (16), based on input from industry, academia, and consumers, as well as state and local food regulators, to assist food establishment employees in preparing safe food. The document is intended to serve as a guide for preparing a simple plan based on HACCP principles. It includes sections on identifying critical control points, developing corrective actions, carrying out verification procedures (e.g., checking monitoring and corrective action records), and maintaining facilities equipment. USDA/FSIS Guidelines and Directives The Meat and Poultry Inspection Manual of the Food Safety and Inspection Service of the Department of Agriculture (FSIS/USDA) (17) contains some gener-


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al guidelines for frying meat and poultry products. Observing that deep fat frying times vary with the temperature of the fat, the amount of replacement fat added periodically, and treatment of the fat during use, the guidelines state that “excessive foaming, darkened color and objectionable odor or flavor are evidence of unsuitability and require fat rejection.” The guidelines also state that the frying fat should be discarded “when it foams over the vessel's side during cooking or when its color becomes almost black as viewed through a colorless glass container.” The serviceable life of fat can be extended by holding the frying temperature below 204°C (400°F), replacing one third or more each day, filtering as needed, and cleaning the system at least weekly. Adding an antifoam agent (dimethylpolysiloxane) to fresh fat is recommended. For poultry, the FSIS guidelines advise that “to completely fry poultry parts, time and temperature required depends upon product type and weight, and upon equipment. Acceptable frying operation should be carried out at approximately 190°C (375°F) or higher for 10–13 min when parts are not precooked . . . commercially prepared fats may contain antioxidants or antifoaming agents . . . used fat may be made satisfactory by filtering, adding fresh fat, and regularly cleaning the equipment. Large amounts of sediment and free fatty acid content in excess of 2% are usual indicators that frying fats are unwholesome and require reconditioning or replacement. Sediment is usually removed by filtering. Adding fresh fat or new fat reduces the free fatty acid to acceptable levels.” The guidelines note that fat used for fish products is not satisfactory for frying poultry. Solid frying fat may be kept liquid if the holding temperature does not fall below 54°C (130°F) to prevent localized excess heating and fat breakdown during melting. FSIS directive 11.000.2 (18) requires cleaning of frying equipment at regular intervals and allows continuous filtering or flushing with clean fat for limited periods of time and notes that “complete drainage, followed by dismantling and scouring or otherwise thorough cleaning, is necessary for acceptable sanitizing. Traces of water and detergents increase rate of fat breakdown. They must be completely removed from pipelines, valves, filters, and pumps, must be of sanitary construction, readily accessible to cleaning, and preferably constructed of stainless steel. Rubber and some types of plastic connecting lines are not acceptable.” State and City Regulations in the United States Inquiries were made at intervals during 1989–2001 to 35 U.S. State health departments and food control agencies to determine whether regulations and guidelines were available for control of frying fats and frying operations in restaurants and processing plants. The replies generally indicated that there were no specific regulations other than those requiring that fats used in food preparation and food service establishments be obtained from approved sources and are not adulterated. Many health departments replied that there were no specific regulations for frying fats, frying operations, and fried foods other than the general regulations for sanitation and recommendations in the 1999 Food Code or earlier versions of the Code.


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The State of Wisconsin’s Department of Health and Social Services stated candidly that its Restaurant Inspection Program does not have any procedures for checking frying fats in restaurants. “Our only concern is that frying fats and oils be obtained from an approved source and be maintained in a reasonably clean condition. Due to high cooking temperatures used in deep frying operations, frying fats and oils have not been considered a public health hazard as it relates to bacterial contamination. Deep-frying operations in restaurants are viewed as an issue of food ‘quality’ rather than food ‘safety’. Typically, deep-frying operation problems are related to exhausting fumes and concerns regarding consumer complaints related to food odors and off taste that may result.” The Food Protection Division of the Allegheny County Health Department (Pittsburgh, PA) has no specific regulations for control of frying fat or fried food quality other than regulations designed to protect consumers from food that contains pathogens. The Department does note that “when oxidation occurs or fatty acids increase in oils due to usage, the oils will have a lower smoke point or a fishy, rancid taste thus rendering them unusable from a quality standpoint.” The Chicago Department of Health regulates fats and oils under the general provisions of chapter 4–344 of the Municipal Code of Chicago, which addresses sanitation practices in food establishments. Food products require approved labels and should be free of rancidity. When routine inspections are made, frying fats are checked for color, sediments, and foreign objects as well as excessive smoke. If necessary, fat and oil samples are collected for determination of rancidity by the Kreis test. The Fulton County (Atlanta, GA) Food Service Sanitation Regulations do not mention frying fats except for the cleaning of frying equipment and proper disposal of spent cooking fats. The State Department of Health regulates Food Service establishments in South Dakota. Cooking equipment that utilizes oil or grease is required to be located under exhaust hoods that vent to the outside. Plumbing systems must comply with the state Plumbing Code that requires grease-traps to prevent grease from entering wastewater systems. The FDA’s Division of Federal-State Relations advised the Connecticut Department of Health (in response to an inquiry to FDA in 1990) that (i) there is no standard frequency for filtering fat used in deep-fat frying operations (the filtering material should be clean and the oil should be clear and properly stored); (ii) any presence of “off” odors or visible evidence of foreign material, filth, or other adulterants would warrant discarding the fat; and (iii) fat must be adequately protected from contamination during use, storage, or filtering. The State of Montana’s Food and Consumer Safety Section regulations require the following: • Ventilation hoods in food service establishments to be installed at or above all commercial type deep fryers, broilers, fry grills, steam-jacketed kettles, hot-top ranges, ovens, barbecues, rotisseries, dishwashing machines, and similar equipment which produces comparable amounts of steam, smoke, grease, or heat.


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• Ventilation hoods and devices shall be designed to prevent grease or condensation from collecting on walls and ceilings, and from dropping into foods or onto foodcontact surfaces. Filters or other grease-extracting equipment shall be readily removable for cleaning and replacement if not designed to be cleaned in place. The Denver Department of Health requires in addition to adequate ventilating hoods, use of a velometer to test equipment in restaurants to ensure that the hoods maintain adequate air velocities. The St. Louis Department of Health’s Food Service Establishment ordinances also require that ventilating hoods be designed to prevent grease or condensation from collecting on ceilings and walls or from dripping onto food contact surfaces, and specifies that grease extracting equipment be readily removable for cleaning if not designed to be cleaned in place. The New Orleans Department of Health requires food service establishments to have grease control devices for separating and retaining water-borne fats, oil, and grease before the wastewater exits the trap and enters the sanitary sewer collection and treatment system. Discharged wastewater should be free of oil or grease exceeding 250 mg/L. Specifications and instructions are provided for grease interceptors and operation of oil and grease waste disposal systems. Regulations and Guidelines in Europe and Other Countries Although federal, state and local agencies in the United States are concerned primarily with greater control or elimination of food-borne pathogens from the food supply, other countries, chiefly in Europe, have issued regulations and guidelines intended to assist in providing better quality as well as safe fried foods. Between 1990 and 2001, 53 countries were contacted about regulations for frying fats and fried food. Responses were received from 34 countries, including 19 of 21 European countries. Austria, Belgium, Chile, France, Hungary, Italy and Spain have specific laws, regulations, or standards for frying fats. Other countries have no specific laws or regulations for frying fats although several countries (Finland, Germany, The Netherlands, Norway, Portugal and Sweden) enforce measures for practical control in food establishments. Regulations or guidelines of individual countries are shown in Table 12.2. Additional information follows on regulation of frying fats and fried foods in these and several other countries. Australia The National Food Authority, established in August 1992, is responsible for the development of food standards and food safety education. Enforcement of food standards and surveillance of food establishments are carried out by the states and territories, which have their own food laws and regulations. Frying fats are not regulated in detail by the 1987 Australian Food Standards Code, which does prescribe standards for various foods, including frying fats, and states that edible fats and oils used in frying may contain sorbitans and polysorbates as well as not >10 mg/kg dimethylpolysiloxane.




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Australian Defense Force specification 5–5-2 (November 1984) requires that deep-fat frying be in accordance with good manufacturing practice and comply with state and territory food regulations. Solid fat for deep-fat frying should comply with the following: (i) moisture, not >3 g/kg; (ii) free fatty acids, not >1 g/kg; (iii) slip melting point between 38 and 49°C; (iv) peroxide value, not >2 mEq/kg; (v) gallates, not >0.1 g/kg; and (vi) clean flavor and free from objectionable odor. Liquid fat for deep-frying should comply with similar requirements for moisture, free fatty acids, peroxide value, and gallate content. In addition, saturated fatty acid content should not be >500 g/kg total fatty acids. Fats for deep-frying should not contain mineral oil or >50g/kg erucic acid. According to the Victoria Health Department, municipal councils are responsible for monitoring food premises. Frying oils are subject to collection and analysis for iodine value, saponification value, acid value, peroxide value, and unsaponifiable matter, as well as qualitative tests for adulterants. Some local councils use Oxifrit Test kits to determine the degree of deterioration of frying fats used in kitchens and bakeries. Austria The Austrian Codex Alimentarius (Austrian Foodstuffs Book) states that frying fat should not exhibit unpleasant odor and taste, unacceptable appearance (dark color, foaming), or a high level of carbonaceous residue. Also, frying fats should have an acid value 170°C, and total polar compounds 10%, total polar compounds >25%, viscosity >37 mPa ⋅ s at 50°C (food fats) or 27 mPa ⋅ s at 50°C (food oils), or smoke point 2% linolenic acid. The law specifically forbids preparation of fried food in equipment not provided with temperature control. Frying fats should not transfer to the fried food improper odor or taste. The sale of used oils and fats for subsequent use in processing food products for human consumption as well as direct or indirect reuse in the food industry is forbidden. Chile Paragraph V, Article 226 of the 1998 Food Law requires that vegetable oils and lard used for frying should be discarded if (i) free acidity expressed as oleic acid is


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>1%; (ii) smoke point is 1%, or total polar compounds are >25%. Czech Republic Guidelines of the National Health Institute effective January 1, 1995 include recommendations that total polar compounds in frying oils should be 25% total polar compounds are unfit for human consumption. Germany There are no specific laws or regulations in Germany for control of frying fats. Recommendations resulting from the first two DGF symposia on frying fats (5,6), however, have been generally applied to the control of edible fats and oils and frying fats. These recommendations were established following reports of gastrointestinal distress after fried food was eaten. According to A. Seher of the Federal Institute for Fat Research in Münster, an epidemiological group was unable to link abused fat with these episodes, but it revealed that many restaurants were abusing fat, particularly those frying meaty foods. According to the 1973 DGF recommendations, used frying fats are considered to have deteriorated if (i) taste or flavor is unacceptable, (ii) smoke point is 1%. After development of the method for determining total polar compounds in 1979, the DGF recommended allowing no >27% total polar compounds in food fats. The basic recommendations of the DGF are still valid. Recommendations adopted by the Arbeitskreis Lebensmittelchemischer Sachverstandiger der Lander und des Bundesgesundheitsamtes (ALS) (Working Sector of the Food Chemical Authorities of the Local and State Health Offices) in 1991 are as follows: sensory characteristics (appearance, odor, and taste) of frying fats are of primary importance; petroleum ether–insoluble fatty acids, maximum 0.7%; total polar compounds, maximum 24%; smoke point, minimum 170°C; smoke point difference (from unheated fat), maximum 50°C; acid value, maximum 2.0%.


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A third International Symposium on Deep-Fat Frying, held March 20–21, 2000 in Hagen/Westphalia, Germany, resulted in adoption of the following recommendations for frying oils (8): 1. The principal quality index for deep fat frying should be the sensory parameters of the food being fried. 2. Analysis of suspect frying fats and oils should utilize two tests to confirm abuse, as follows: Total polar compounds Polymeric materials (polymerized triglycerides) 3. The use of rapid tests for monitoring oil quality is recommended. Rapid tests should exhibit the following characteristics: Correlate with internationally recognized standard methods Provide an objective index Be easy to use Be safe for use in food processing/preparation areas Quantify the oil degradation Be field rugged 4. Affirming previous work: There are no health concerns associated with consumption of frying fats and oils that have not been abused at normal frying conditions. 5. Encourage development of new and improved methods that provide fats and oils chemists and the food industry with tools to conduct work more quickly and easily. Work should strive to develop methods that are environmentally friendly, using lower quantities of and less hazardous solvent systems. 6. Encourage and support basic research focused on understanding the dynamics of deep fat frying and the frying process. Research should be cross-disciplinary, encompassing oil chemistry, food engineering, sensory science, food chemistry, and nutritional sciences. 7. One of the basic tools to ensure food and oil quality is the use of filtration. Filter materials should be used to maintain oil quality as needed. 8. Used, but not abused, frying oils may be topped up or diluted with fresh oil with no adverse effects on quality. Abused fats and oils were defined in the first two recommendations. The symposium delegates left for further discussion the subject of what constitutes a long-life frying oil claim in keeping with recommendations 1 and 2. Hungary There are no mandatory regulations in Hungary for frying oil quality. Standard No. Msz-08–1907–87, valid January 6, 1988, recommends determination of total polar


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compounds for estimation of fat quality as follows: 30%, frying fat is unusable. The National Institute of Food Hygiene and Nutrition recommended that iron and copper fryers should not be used, and that frying temperatures should be kept between 160 and 180°C. Smoke point 180°C; (iii) total polar compounds should not be more than 25 g/100 g; (iv) prepare the food to be fried properly, avoiding the presence of water and addition of salt and spices, which accelerate changes in frying fat, as much as possible; (v) allow excess oil to drain from the food; (vi) change the oil frequently, check the quality of the oil or fat during frying, and do not use oil too long (indicated by darkened color, viscosity, and tendency to smoke); (vii) filter the oil if it will be used again and clean the filter and fryer because charred crust, viscous oily residue, or old oil accelerates alteration of the oil; (viii) avoid “reconditioning” oil (addition of fresh oil) because fresh oil changes rapidly when in contact with used oil; and (ix) protect frying oils and fats from light. Japan There are no formal regulations in Japan regarding the quality of frying oil. With respect to food establishments, however, the following guidelines exist for determining when to discard frying oil: (i) if the smoke point is 2.5; and (iii) if the carbonyl value is >50. Luxembourg There are no specific regulations for frying fat in Luxembourg. General regulations in force for all foods, however, also apply to frying fats. For practical control in food establishments preparing fried food, the food inspector uses E. Merck’s Fritest. If the Fritest is positive, then frying fat is checked for free fatty acids, total polar compounds, taste, color, odor, and appearance. Use is allowed of up to 3 mg/kg of dimethylpolysiloxane in frying fats. The Netherlands Food laws in The Netherlands are enforced by 16 food inspection services, each covering an inspection area of about one million people. Inspectors sample the frying oil or fat in restaurants, snack bars, fish shops, and so forth. Samples are brought to the laboratory where they are checked for odor, taste, acid value, and DPTG content. Frying fat or oil is “unfit for human consumption” if the acid value is >4.5 and/or DPTG content is >16%.


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Portugal There are no specific regulations for frying fats and oils in Portugal. However, the Ministry of Agriculture’s Food Quality Institute examines frying and cooking oil for color and odor and also by E. Merck’s Fritest and Oxifrit Test and Libra Laboratories’ Veri-Fry quick tests. If positive, the oil is analyzed for content of total polar compounds, which should be no >25%. It is recommended that frying temperatures should be not be greater than 180°C. Scandinavian Countries The Scandinavian countries have no specific laws or regulations applicable to frying fats. General regulations applicable to edible fats and oils apply to frying fat. Norway’s laws require foods to be free of pollutants and toxic substances and specify that only tocopherols and citric acid may be added to fats and oils. For practical control in restaurants and fast-food establishments, Norwegian inspectors may use organoleptic evaluation or the Fritest. In Sweden, the Oxifrit Test is used as a quick test, and the method for total polar compounds is used as a reference method. In Finland, fat is considered spoiled when color, odor, and taste are 2.5 and the smoke point is 2, and smoke point is 16, acid value is >2, and smoke point is

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