Recent Trends in Soft Beverages (Woodhead Publishing India)

Recent Trends in Soft Beverages Recent Trends in Soft Beverages-FM.indd 1 3/7/2011 6:28:28 PM 1 Introduction to cof...

Author: L. Jagan Mohan Rao | K Ramalakshmi

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Recent Trends in Soft Beverages

Recent Trends in Soft Beverages-FM.indd 1

3/7/2011 6:28:28 PM

1 Introduction to coffee

1.1 Origin and history of coffee Coffee is native to Ethiopia and introduced to India during 1600 AD. Over the centuries, numerous legends have been accumulated about the discovery of coffee. Possibly, the earliest references to the use of coffee are to be seen in the Old Testament. Coffee cultivation had begun as early as the 16th century. The most well-known story – the discovery of the coffee plant is concerned with a goatherd tending his flock in the hills around a monastery on the banks of the Red Sea. He noticed that his goats, after chewing berries from the bushes growing there, started prancing excitedly. A monk from the monastery observed this behaviour, took some of the berries, roasted them, and brewed them. When he served, the brew kept his people more alert during the long prayers at night and this shows the birth of the world’s most stimulating beverage [1]. The word coffee is derived from the Arabic word “quahweh”, which is a poetic term for “wine”. Since wine is forbidden to devout Muslims, the name was changed to coffee. The wild coffee plant is indigenous to Ethiopia, from which it is spread to Arabia and nearby countries. The transport of coffee from the countries near Arabia to other parts of the world was limited; the raw beans were not allowed out of the country without steeping in boiling water or heating to destroy their germinating power. Strangers were not allowed to visit the plantations; it was Baba Budan, a pilgrim from India, who smuggled out a few seeds capable of germination. He planted the seeds in the Western Ghats of Coorg in South India during 1600 AD. The cultivation was expanded during British rule. In Brazil, coffee entered through a Brazilian officer who, while on visit to French Guyana in 1727, received a plant hidden in a bouquet of flowers as a token of affection from the governor’s wife. This was the start of coffee plantations in Brazil, which now holds supremacy in the world.

1.2 Coffee production scenario Coffee is one of the most important agricultural products traded worldwide. It is grown and exported by over 70 developing countries 3

Chapter 01 Part I.indd 3

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4


in the tropical and subtropical belt and developed countries import and consume most of it. Out of these, 51 countries, including Brazil, Colombia, Guatemala, India and Mexico are responsible for more than 99% of world output and are exporting members of the international coffee agreement. The coffee production statistics are given in Tables 1.1 (2005–06) and 1.2. The export details of coffee from India are given in Tables 1.3 and 1.4. India exports maximum amount of coffee to the countries viz., Italy, Russia, Germany, Spain, Finland, Greece, etc. Table 1.1 List of coffee-producing countries

No.

Country

Type of coffee

Production (Bags in million, 1 bag =60 kg)

1

Brazil

Arabica and Robusta

35.00

2

Cameroon

Arabica and Robusta

1.00

3

Colombia

Arabica

11.0

4

Costa Rica

Arabica and Robusta

0.60

5

Cuba

Arabica

0.28

6

Dominican Republic

Arabica

0.50

7

Ecuador

Arabica and Robusta

0.70

8

El-Salvador

Arabica

1.30

9

Ethiopia

Arabica

4.50

10

Guatemala

Arabica and Robusta

3.70

11

Guinea

Arabica

4.50

12

Haiti

Arabica

0.37

13

Honduras

Arabica

3.00

14

India

Arabica and Robusta

4.60

15

Indonesia

Arabica and Robusta

6.70

16

Ivory Coast

Robusta

2.50

17

Kenya

Arabica

1.00

18

Madagascar

Arabica and Robusta

0.70

19

Mexico

Arabica

4.20

20

Nicaragua

Arabica

1.40

21

Uganda

Arabica and Robusta

2.70

22

Peru

Arabica

2.70

23

Philippines

Arabica and Robusta

0.50

24

Venezuela

Arabica

0.80

25

Vietnam

Robusta

11.00


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5

Introduction to coffee Table 1.2 India – Coffee area, production and productivity [2]

Season

Area (ha)

Production (MT)

Arabica Robusta

Total

Productivity (kg/ha)

Arabica Robusta Arabica Robusta

Average

2000–01

146502

167342

313934

104400

19680

713

1175

950

2001–02

149056

171681

320737

121050 179550

812

1046

937

2002–03

146780

173835

320615

102125 173150

696

996

859

2003–04

148389

176735

325124

101950 168550

687

954

832

2004–05

153280

180058

333338

103400 172100

675

956

826

2005–06

151547

189804

341351

94000

180000

620

948

803

2006–07

151861

191179

343040

99700

188300

657

985

840

2007–08

148354

193959

342313

92500

169500

624

874

765

Table 1.3 Earnings from export of coffee from India (2008) [2]

S. no.

Destination

1

Quantity

Unit value (Rs/MT)

Total value (Rs in crores)

MT

%

Italy

53804

24.57

88567

477

2

Russian Federation

25183

11.50

100657

253

3

Germany

14236

6.50

101695

145

4

Belgium

10615

4.85

94201

100

5

Spain

8802

4.02

81100

71

6

Finland

7914

3.16

92434

73

7

Greece

5470

2.50

80084

44

8

Slovenia

5400

2.47

77728

42

9

Croatia

5011

2.29

83261

42

10

Ukraine

4916

2.25

106524

52

11

Others

77588

35.89

104503

811

Total

218939

100

93741

2110

Table 1.4 Export of speciality and value-added coffee from India*

Grade

2000

2001

2002

2003

2004

2005

2006

2007

2008

Speciality coffee Mysore Nuggets 710 AB Monsoon Malabar 1156 AA


465

760

1037

998

828

1207

1088

838

1204

1827

1832

2528

2180

2462

3425

1516

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6 Monsoon Robusta AA Monsoon Arabica TR Monsoon Robusta TR Monsoon Malabar Basanally Robusta Tapi Royale


861

669

822

824

18

13

13

12

1119

1205

1601

1082

529

9

72

27

8

60

15

3 27

Total

50

52

145

152

289

227

415

411

2541

3059

3957

4160

4259

3828

3809

2680

49522

6540

7807

8947

8769

9457

9860

5981

Value-added coffee Instant

41820

43233

44978

43691

53916

54315

54830

64830

29511

Ground

7

18

17

50

111

51

98

316

57

Roasted seed

147

36

0.4

27

41

20

83

54

51

Total

41974

43287

44995

43767

54068

54386

55012

65246

29619

*quantity in MT [2]

1.3 Botany, agricultural practices and propagation The coffee plant belongs to Rubiaceae family (Table 1.5), which has over 70 species of coffee. But only seven of them have significant economic importance. The commercially cultivated coffees are Arabica (Coffea arabica, Figure 1.1) and Robusta (Coffea canephora, Figure 1.2). Coffea libera, another species, was devastated during the 1940s by an epidemic of trachemycosis due to infection by Fusarium xylaroides and the commercial growth of this species has effectively ceased since then. C. roubusta is noted for resistance to disease and contains more caffeine than C. arabica, and is thus more economical in the manufacture of instant coffee [3].


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7

Introduction to coffee

Figure 1.1 Coffee arabica

Figure 1.2 Coffee Robusta Table 1.5 Systematic taxonomical position of coffee

Division

Angiosperm

Class

Dicotyledonous

Family

Rubiaceae

Genus

Coffea

Species

Arabica, Robusta, etc.

The coffee plant is a small tree and can grow up to 25 ft (7.6 m) in the wild state. C. arabica and C. Robusta are maintained at 5 ft (150 cm) and 5.5–6.0 ft (170–185 cm), respectively. These trees are pruned for two reasons – to facilitate harvesting and maintain optimum tree shape. The primary branches are opposed and horizontally drooping, and the leaves grow in pair on short stalks. They are about 15 cm of length in C. arabica and longer in C. canephora – oval and fairly dark green in colour. Various methods of propagation are being used, including cuttings, grafting and layering. The use of cuttings is the normal commercial practice. The coffee plants start yielding fruits within 3–5 years and last up to 30–40 years. An altitude of 2000–4000 ft (600–1200 m) is ideal for coffee, but it can be grown at


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6000 ft (1800 m). The higher the altitude, the better is the quality of coffee. The limiting factor is that coffee cannot withstand frost. The ideal climatic condition of coffee is 30–40°C and rainfall 60–80 in. (150–200 cm). The yield of coffee is totally dependent on the flowers produced by the plants and more importantly, on the percentage of fruit set from flowers. The blossoming largely depends on timely rainfall, which induces the flower bud to open within 7–10 days. In recent years, sprinkler spraying is widely used for opening flower buds. Insects carry out pollination of flower. The normal development from flower to fruit requires 5–8 months in C. arabica and 9–10 months in C. Robusta. The fruits are borne in clusters at each leaf axil. In the case of C. arabica, each cluster carries 15–20 fruits per node whereas there are 40–80 fruits in C. Robusta. The berry (Figure 1.3) consists of an outer skin, over a fleshy pulp, in which two seeds are embedded. Seeds are flat on one side and convex on the other side. Occasionally, one seed rounded on both sides (peaberry) may be found. The seed is covered by a thin silver skin as well as by a thick layer called parchment [1]. Red berry skin (epicarp) Pulp mesocarp Mucilage Parchement (endocarp) Silver skin (spermoderm) Endosperm

Figure 1.3 Coffee berry – cross-section

1.4 Processing 1.4.1 Green bean processing The processing of green coffee is carried out by two methods namely, wet method and dry method (Figure 1.4). In the wet method (Figure 1.5), only ripe fruits having a reddish brown colour are picked, graded and fed to a pulper to remove the outer skin and mucilage. The parchment (Figure 1.6) is washed thoroughly and dried. The coffee prepared by this method is called parchment coffee, and is practiced in Columbia, Kenya and most of the South and Central American Countries. India also processes arabica coffee by this method. In


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9


the dry method (Figure 1.7), ripe, green and under-ripe fruits are sorted out and then dried separately. The coffee obtained by this method is called cherry coffee. Consumers favour parchment coffee from the wet method [4]. Fresh cherries Wet processing

Dry processing

Biochemical Mechanical

Mucilage removal

Drying

Chemical Washing

Hulling

Drying

Sorting and grading

Polishing

Packing

Sorting and grading

Shipping

Packing Shipping Figure 1.4 Cofee processing - wet and dry methods


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Figure 1.5 Wet processing

Figure 1.6 Parchment coffee

Figure 1.7 Dry processing


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11

1.4.2 Roasting of coffee Roasting is the first step in the preparation of any consumable product from green coffee. The characteristic aroma is developed during roasting. Coffee received at the roasting plant should be free of extraneous matter, but in practice, it is usually contaminated with chaff, strings, wood splinters, stones, pebbles, coins, nails etc., and therefore these must be cleaned well. Large particles are removed using screens and light particles are blown off through air blasting. Nails and other materials are removed using magnetic separators.

Roasting process Roasting of coffee is a process of exposing the coffee beans to a warming process that is sufficient to drive off the free and bound moisture; dry beans are heated to a temperature of 200–250°C. The time required for roasting is 5–10 min in a continuous roaster and more than 20 min in non-continuous roaster [4]. The degree of roasting is critical for the development of flavour in the bean and determines many of the flavour characteristics of the brewed coffee. The relationships between different roasting temperatures, weight loss and cup quality are summarized in Table 1.6. The degree of roast is usually assessed from external colour, a final quantitative assessment made using colour reflectance meters [5, 6]. The conventional roasting equipment consists of a metal container in which green coffee is heated while it is continuously rotated (Figure 1.8). Heat may be supplied by conduction from hot air or more frequently by a mixture of both the methods of heat transfer together. It is necessary that during the roasting process, heat may be supplied quickly, uniformly and the beans are continuously stirred.

Figure 1.8 Coffee roaster


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Table 1.6 Roasting parameters and cup quality

Temperature (°C)

Roast

Weight loss %

Cup quality

180–200

Very light

10–12

Acidic taste, poor aroma

200–220

Light

12–15

Better aroma, acidic cup

220–230

Medium

15–20

Best aroma, optimal quality,

230–240

Dark

20–23

Dark colour, (aroma preferred by Europe)

240–250

Very dark

23–25

Very dark colour, (good taste for Italians)

Different types of roasters are available. Continuous roasters are used in large scale processing plants because these have greater efficiency, and ensure better uniformity than batch-type roasters. Continuous roasters consist of either a perforated drum or a cylinder for roasting and subsequent cooling of the beans. The rotating drum principle is used in the commercial roasters. Fluidised bed roasters are used for large scale roasting of the coffee beans. Both heating and cooling are achieved in the same vessel by a fluidised solid contact technique. Fluidised roasters have better control parameters and deliver the product with uniform roasting. The spouted bed roaster is a variant of the fluidised bed roaster that has an advantage in large scale roasting and tends to develop unstable fluidisation [7, 8, 9 ]. The special feature of the spouted bed roaster is that it has no moving parts or vibratory units, which may damage the final product. The roasting chamber is transparent so that the colour of the roasting beans can be easily controlled visually [10].

Changes during roasting Many types of physical and chemical changes occur during roasting, including changes in colour, size and shape of the bean. The important changes that take place during roasting are loss of moisture, loss of organic matter and production of CO2; swelling of bean and consequent changes in density of the bean; decrease in the breaking strength of the bean, caramelisation of sugar and other constituents, with consequent changes in colour and formation of typical aroma compounds; decrease in the tannin like constituents and sugars increase in water soluble matter and formation of niacin, and increase in its content during roasting. The chemical composition of green, roasted and brewed solids is presented in Fig.1.9 [11]. Roasting results in loss of weight of the bean. Roasting produces a large amount of CO2 inside the bean, which under high pressure bloats the bean


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13


with the corresponding reduction in the specific gravity from 1.2–1.3 to 0.6–0.8. This results in porous structure and reduction in the breaking strength of the roasted bean. The colour of the bean changes from grey green to light brown, dark brown or almost black depending on the type of roast. The pH of the roasted coffee brew falls down to 5.5–5.0 from the pH of 6.0 of green beans. This is mainly due to the formation of organic acids (Figure 1.10). In general, light roasts give more acid cup than dark roasts. The pH of brew cup from medium roast is 5.0, while that of dark roast is up to 5.3. Roasted coffee beans

Green coffee beans starches and pectins 13%

starches and pectins 14%

cellulose (Hyd) 13%

soluble carbohydrates 9%

non volatile acids 7%

trigonelline 1%

non volatile acids 7% caffeine 1%

protein 12%

ash 3%

cellulose (Hyd) 15%

soluble carbohydrate 10%

cellulose (non Hyd) 18%

water 12%

CO2 2%

cellulose (non Hyd) 18%

water 2%

trigonelline 1%

caffeine 1%

oil 11%

protein 13%

ash 4%

oil 13%

Brewed solids non volatile acids 33%

soluble carbohydrates 38%

caffeine 5% ash 17%

oil 1%

protein 6%

Figure 1.9 Chemical composition of green, roasted and brewed solids

Sugars and proteins break down to aldehydes, alcohols and acids. Sucrose is the major sugar, which suffers heavy loss during roasting. Proteins are denatured and are broken down to amino acids. The most significant change occurring during roasting is the formation of aroma compounds. Roasted whole beans retain the characteristic aroma for about a week under normal atmospheric condition. This is mainly due to the carbon dioxide built-up inside the bean providing an inert atmosphere. The volatile compounds of coffee are largely responsible for the aroma. The green bean does not possess any appealing flavour and its infusion is


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14


unpalatable. Roasted coffee contains more than 1000 volatile compounds [12]. The chemical composition of green and roasted coffee, and the important precursors for the formation of volatiles are given in Tables 1.7–1.9 [13]. O

O CH

CH

OH

O

C

CH

CH

COOH

C

HO OH

OH

O

HO

HO

HO

COOH

Quinic acid

Caffeic acid

Caffeoylquinic acid

OH

HO

+

OH

OH

H

O CH

CH

C

OH CH

+

Degradation rapid OH

HO

HO

OH HO

OH

OH

HO

Catechol

Free caffeic acid

OH

HO

4- vinylcatechol

O

+

+

Degradation slow

HO HO

COOH

Quinic acid

CH 2

O

OH Pyrogallol

Catechol

Hydroquinone

OH

HO OH

+ HO COOH

HO HO Gallic acid

Figure 1.10 Formation of organic acids during roasting Table 1.7 Chemical composition of green coffee


Constituent

Arabica (%)

Robusta (%)

Caffeine

0.9–1.2

1.6–2.5

Trigonelline

1.0–1.2

0.7–1.0

Ash

3.0–4.2

4.0–4.4

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Introduction to coffee Chlorogenic acids

5.5–8.0

7.0–10.0

Organic acids

1.5–2.0

1.5–2.0

Sucrose

6.0–8.0

5.0–7.0

Reducing sugars

0.1–1.0

0.4–1.0

Total polysaccharides

44.0–55.0

37.0–47.0

Lignin

2.0–3.0

2.0–3.0

Protein

11.0–13.0

11.0–13.0

Lipids

14.0–16.0

9.0–13.0

Table 1.8 Chemical composition of roasted coffee

Constituent

Arabica (%)

Robusta (%)

Caffeine

1.0–1.3

1.7–2.4

Trigonelline

0.5–1.0

0.3–0.7

Ash

3.0–4.5

4.0–6.0

Chlorogenic acids

2.2–4.5

3.8–4.6

Organic acids

1.0–2.4

1.0–2.6

Sucrose

Nil

Nil

Reducing sugars

0.2–0.3

0.2–0.3

Polysaccharides

24.0–39.0

25.0–37.0

Protein

~ 12

~ 12

Lipids

~ 13

~ 10

Water solubles

26.0–30.0

28.0–32.0

Table 1.9 Generation of coffee volatiles during roasting

Green coffee Lipids Fatty acid

Roast coffee Aliphatic hydrocarbons

Higher terpenoids

Monoterpenoids

Lignin

Phenolic compounds

Starch Sugars

Acids and aldehydes, Ketones

Peptides , amino acids

Nitrogenous and sulfurous compounds

Trigonelline

Nitrogenous compounds

1.4.3 Subsequent operations After developing the coffee flavour by roasting, efficient extraction of the roasted coffee solubles and volatiles that contribute to the coffee flavour and aroma is essential. The solubles could be extracted from the whole roasted


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beans, but the yield would be low and flavour would be poor. Extraction may be made to give a higher yield of solubles by breaking down the whole bean to smaller pieces. Grinding is essential to obtain maximum extraction of solubles including aroma and flavour. Various types of grinders based on the principles of cutting, shearing and crushing are available for the purpose of size reduction during large scale grinding of coffee beans. After grinding, the coffee is suitably packed and stored [14].

1.5 Chemical composition The chemical composition of green coffee depends mainly on the variety of coffee, agricultural practices, processing and storage conditions. Green coffee is especially characterized by its content of caffeine, trigonelline and chlorogenic acids, otherwise its composition is similar to other vegetable substances with their protein, carbohydrates, vegetable oil and mineral content. However, the carbohydrate portion consists mainly of polysaccharides, and the physical hardness of the same is due to mannan (low-degree polymerization). The two main species of coffee, viz., arabica and Robusta differ in composition (Table 1.7) with respect to parameters such as caffeine, chlorogenic acid, and lipids.

1.5.1 Moisture Moisture affects the quality and storage of coffee. It is generally recognized that green coffee should not be allowed to reach moisture content in excess of 12% corresponding to a relative humidity of 70%. Higher moisture content will result in loss of green colour, favour mould growth, flavour deterioration and possibility of mould toxin formation [15]. Deterioration is also markedly accelerated by temperature (low temperature is preferred for retaining the colour and flavour quality). Moisture content of 10.5% for plantation coffee and 11% for cherry coffee is generally recommended. The moisture content in green, roast and instant coffees is determined by air oven, vacuum oven or Karl Fischer method. Moisture meters are now available for quick measurement of moisture content in green coffee. The most commonly used Kappa moisture meter works on the principle of dielectric constant. The instrument needs calibration using a reference method, i.e. oven method [16].

1.5.2 Caffeine This is perhaps the most important chemical component studied in coffee due to its reported physiological effects. Caffeine (Figure 1.11), 1,3,7trimethylxanthine, is an alkaloid with a substituted purine ring system. The


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main physiological effect of caffeine appears to be as a stimulant to the central nervous system. It has an effect on the cardiovascular system with slight increase in blood pressure and heart output. Caffeine also increases the gastric acid secretion. It undergoes bio transformation in the human body to form methylated derivatives of uric acid. Caffeine is definitely not lethal to the system when ingested in the form of beverages, unless one consumes 75 cups of coffee, 125 cups of tea or 200 cola beverages within 30 minutes [17]. O H3C O

N

N N

CH 3

N

CH 3 Figure 1.11 1,3,7- trimethylxanthine

The caffeine content of green coffee bean varies according to the species; Robusta coffee contains about 2.2%, arabica about 1.20% and the hybrid ‚arabusta‘ about 1.72%. Environmental and agricultural factors appear to have minimal effect on the caffeine content. During roasting, there is no significant loss in terms of caffeine. A typical cup of regular coffee contains 70–140 mg of caffeine depending on preparation, blend and cup size [15]. The structure of caffeine is that of purine derivative xanthine, with methyl substituents attached at positions 1, 3 and 7. Reports on the bio-synthesis and degradation of caffeine in coffee are limited. Both processes occur more rapidly in immature than mature fruit. The main biosynthesis route utilises the purine nucleotide for the formation of caffeine is well documented [18]. In coffee plants caffeine is synthesised from xanthosine via 7-methylanthosine, 7-methylxanthine and theobromine. S-adenosylmethionine (SAM) is the actual source of the methyl groups. The caffeine is degraded relatively slowly and involving demethylation steps to yield theobromine and theophylline. Theophylline is catabolised to xanthine via 3-methylxanthine. But it is unclear whether 3-methylxanthine and/or 7-methylxanthine are intermediates in the conversion of theobromine to xanthine. Xanthine is metabolised to urea [18]. On roasting, caffeine is unchanged though some loss occurs due to sublimation. Caffeine is the most important compound in the analytical parameters of coffee and in the standards and specifications of coffee and


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coffee products. There are several analytical procedures for the determination of caffeine in coffee such as Baily Andrew, Levin’s and HPLC methods [13].

1.5.3 Organic acids Chlorogenic acid is one of the important components along with the other organic acids (Figure1.12) present in green and roasted coffee beans. Chlorogenic acids contribute to acidic and astringent tastes. Chlorogenic acid comprises of caffeoylquinic acid ester of caffeic and quinic acids, deiaffeoylquinic acid, feruloylquinic acid, coumaroylquinic acid, caffeoylferuloylquinc acid and feruloylcaffeoylquinic acid. These isomers suffer heavy losses during roasting and the degree of loss depends on the type of roasting. Robusta coffee contains high amounts of chlorogenic acid compared to arabica coffee. High astringency of Robusta coffee is attributed to dicaffeoylquinic acids and the feruloylquinic acids. Further, the higher content of 4, 5-dicaffeoylquinic acid in Robusta appears to contribute to a peculiar lingering metallic taste, which is a negative sensory effect [19]. Chlorogenic acid is determined by spectrometric and chromatographic methods, which allow separation and quantification of individual isomers. During roasting, polysaccharides undergo degradation resulting in several organic acids which contribute to the acidity of coffee brew, and this is an important sensory quality. The acids reported are citric, malic, lactic, quinic, pyruvic, acetic, oxalic, tartaric, propionic, butyric, valeric, etc.

1.5.4 Trigonelline and nicotinic acid Trigonelline (Figure 1.13) present in green coffee (about 1%) degrades rapidly on roasting, yielding nicotinic acid, nicotinamide and a range of aroma volatiles, which includes pyridines and pyrroles. Roast coffee contains 10–40 mg of nicotinic acid per 100 g depending on the degree of roasting [16].

1.5.5 Proteins Proteins and amino acids have received relatively little attention. Considerable research [16] has been carried out to correlate the initial protein content in green coffee to the aroma and taste of the coffee brew obtained from the roasted and ground powder, but with limited success. In green coffee, proteins exist in unbound form predominantly in the cytoplasm or are bound to cell wall polysaccharides. Proteins are denatured during roasting and broken down to amino acids. The sulphur amino acids like cystein, cysteine and methionine degrade alone or react with maillard intermediates. Hydroxyl amino acids like


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serine and threonine react with sugars during roasting to yield pyrazine and their derivates, and pyridines and their derivatives. Free amino acids occur only in traces in roasted coffee [20]. O CH

CH

C

OH

OH HO HO

HO

OH

C OH

O HO

Quinic acid

Caffeic acid

O CH

CH

C

O OH

CH

CH

C

OH

OH

HO o-coumaric acid

p-coumaric acid

O CH

CH

C

O OH

CH

CH

C

OH

O

C O

HO OCH 3 HO Ferulic acid

HO

OH

HO HO

Chlorogenic acid

Figure 1.12 Organic acids present in coffee

1.5.6 Carbohydrates Green coffee contains sucrose and a wide range of pol3ysaccharides (arabinogalactan, galactomannan and cellulose). Sucrose is the major sugar which suffers heavy loss during roasting due to caramelisation and other reactions. Because of the severe conditions employed for extraction in instant coffee manufacture, hydrolysis of insoluble polysaccharides takes


2/5/2011 4:49:35 PM

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place yielding soluble oligosaccharides mainly, polymers of mannose and galactose, arabinose and mannose monomers [21]. The sugar analysis involves determination of free sugar in green coffee, oligosaccharides in instant coffee and monosaccharides (after hydrolysis of polysaccharides) in all coffee products. O C

O

COOH

+ N

N

CH3

Trigonelline

Nicotinic acid

Figure 1.13 Trigonelline and nicotinic acid

1.5.7 Melanoidins Proteins and carbohydrates react during roasting, forming melanoidins. Melanoidins are derived from Maillard reactions or from carbohydrate caramelization. The melanoidins are the caramelized substances consisting of complicated structures involving fragments of phenols, carbocycles, N-hetero-cycles, benzenoids and furanoids. Attempts to isolate browning substance in roasted coffee have remained unsuccessful. Melanoidins appear to have a stimulating effect on the stomach intestinal tract causing irritation in some persons. This irritation is reported to reduce substantially by treating the coffee beans with steam prior to roasting [22].

1.5.8 Minerals The ash content of green coffee is about 4% (dry matter basis) of which 40% is potassium (dry ashing at 580C and estimation by flame photometry or atomic absorption spectrometery). In addition to potassium, 30 more elements were quantified in coffee products by atomic absorption or neutron activation analysis and these include magnesium, calcium, rubidium and iron. Manganese content is higher in arabica (25–60 ppm) and lower in Robusta coffees (10– 33 ppm). The other trace elements reported in green coffee include zinc, molybdenum, cobalt, copper, strontium and others. There can be considerable contribution of trace elements to the instant coffee from the processing water and this varies with the source of water employed [23].


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1.5.9 Lipids Lipids constitute one of the major components of green coffee (arabica 14–16% and Robusta 9–13%). Coffee beans are coated with a polar wax (0.2–0.3%), which consists largely of fatty acid esters of 5-hydroxytryptamine, which are known to act as mucosal irritants [12]. The lipids content in boiled coffee, espresso and filter coffee are reported as 2.2%, 0.4% and 0.2% respectively on ground coffee basis. Instant coffee contains very little lipid materials, apart from coffee oil that may be added for aromatization at the end of the process.

1.5.10 Volatile compounds The green coffee is devoid of any appealing taste or aroma. The pleasant flavour of coffee is formed during roasting involving a wide range of complex chemical reactions like oxidation, reduction, hydrolysis, polymerization and decarboxylation. Roasting alters the colour, size and shape of the bean. The degree of roast is based on flavour preference, which varies from place to place. The most important change occurring in coffee during roasting is the formation of aroma compounds. The important aroma precursors are amino acids, sugars and chlorogenic acids. Some minor compounds are formed from other compounds such as terpenes, trigonelline, sterols and lipids. The most significant reaction in coffee aroma formation is interaction between amino acids and reducing sugars (browning reaction), and also the direct caramelisation [24, 25, 5]. The study of flavour compounds includes total volatiles analysis including headspace compounds. Recently, there has been a remarkable progress in the isolation and recovery of the flavour volatiles. Initially, the flavour analysis met with several problems such as (a) the number of volatile substances was extremely large, (b) the compounds varied in physical and chemical properties and in the levels of concentration and (c) isolation and identification procedures could alter the nature of several sensitive compounds resulting in artefacts. In spite of these inherent difficulties, the flavour chemistry of coffee has received maximum attention world over and about 800 flavour components have so far been identified though relatively small number of compounds make a significant contribution to overall flavour. Volatile compounds are being considered desirable at low concentrations while undesirable at higher concentrations. Studies on flavour formation also have received some attention in recent years. The origin of various volatiles [5, 26] in roast coffee is correlated to aroma precursors such as amino acids, proteins and sugars (Table 1.10). The complete mechanism of flavour formation in coffee from the precursors is not well understood. The search for key flavour compounds responsible for the characteristic aroma of coffee has not yielded good results. However, some of the important


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aroma compounds and their contribution to overall flavour are presented in Table 1. 11 [27, 28, 29]. Table 1.10 Formation of aroma volatiles in coffee

Type of volatile compound

Possible precursor

Mechanism of formation

Saturated hydrocarbons, dicarboxylic amino acids Glucose, aromatic amino acids Sugars, fatty acids, amino acids

Pyrolysis, oxidative, decarboxylation

Alcohols

Carbonyl compounds

Reduction

Olefinic hydrocarbons Aromatic hydrocarbons Carbonyl compounds

Pyrolysis Pyrolysis

Phenols

Tannins, chlorogenic acid

Pyrolytic degradation

Mercaptans, sulphides, thiophenes

Sulphur amino acids

Pyrolysis

Thiazoles

Cysteine

Pyrolysis

Furan compounds

Carbohydrates

Cyclisation

Pyrazines

Carbohydrates – Amino acid/ ammonia

-

Pyrroles

Prolines

-

Pyridines

Trigonelline

-

Table 1.11 Possible aroma impact compounds


Aroma compound

Flavour effect

Furyl-2-methanethiol

Fresh coffee aroma (10–500 mg/kg/) Stale note (1–10 mg/kg)

Kahweofuran

Slight coffee note (10–100 mg/kg)

n-furyl-2-methylpyrrole

Stale coffee odour

2-ethyl furan

Burnt, sweet, coffee-like aroma

n-ethyl-2-formyl pyrrole

Burnt, roast coffee

Thiobutyrolactone

Burnt coffee odour

2-methyl-2-acetyl thiophene

Coffee-like aroma

2-methyl isoborneol

Earthy, musty

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1.5.11 Amines Amines are organic bases formed during metabolic processes in all living organisms, thus present in most food products. The predominant amines in green coffee were serotonin and putrescine, followed by spermidine and spermine [30]. Total amine levels in green coffee ranged from 3.03 mg to 4.44 mg per 100 g. During roasting, there was a total loss of putrescine and spermine but less loss of spermidine and serotonin.

1.5.12 Foreign compounds At every stage of processing of coffee beans, there may be deliberate or accidental introduction of some foreign compounds. Additives and contaminants found in some coffee samples are discussed below.

Mycotoxins Fungal attack following coffee borer beetle damage, leads to the formation of viridic acid. The viridic acid test (a colour reaction) has been used to estimate the extent of pre-harvest damage by the coffee borer beetle. Fungal damage to coffee beans can also occur during fermentation processes used to separate the coffee bean from the coffee berry pulp. However, green coffee beans are highly susceptible to fungal attack if they are stored in warm humid conditions. Ochratoxin A can be produced in green coffee beans stored in warm humid conditions, due to Aspergillus ochraceous growth. Improperly stored coffee was found to contain aflatoxin. It is very interesting to note that decaffeinated green coffee beans are much more susceptible to fungal attack, than untreated green coffee. Caffeine has an antifungal effect at or above 2 mg/g. In addition, decaffeinated beans have lost their protective surface wax covering. Roasting does reduce the levels of several mycotoxins, if these are present in green coffee beans. For example, ochratoxin A is reduced by 80–90% on roasting the contaminated coffee beans. Ochratoxin A in coffee beans is estimated by solid-phase micro extraction and liquid chromatography with fluorescence detection [31].

1.6 Additives in coffee Many types of additives or substitutes are used in coffee in order to increase the brew strength. Cyclodextrins used as an additive couples with undesirable taste components and imparts smoothness to the flavour of the beverage. Cyclodextrins are heat stable and addition of cyclodextrin in the concentrated extract does not alter the characteristics of coffee [32]. Chelating agents


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like phytic acid and its alkali metal salts are used to prevent foam and scum formation in the reconstituted instant coffee beverage. Substitutes like chicory, barley, malt and rye are used to increase the brew strength.

1.6.1 Chicory: the adjunct and the extender Chicory is a permitted additive to coffee powder and very safe to the human system. Chicory (Cichorium intybus Linn.) is a tuberous plant of which the root is used for coffee adjunct. The cut pieces of these roots are dried, roasted and ground for mixing with coffee powder. It is cultivated in Gujarat (Jamanagar, Mehsana and Kaira) and Tamil Nadu (Coimbatore and Nilgiris). As per the Indian standard (IS 3802:1992) the coffee content in the coffee-chicory blend shall not be less than 51%. As per the Prevention of Food Adultration Act (PFA), the maximum percentage level of chicory that could be mixed with the roasted and ground coffee is governed by the following two requirements:

(i) C affeine content of the coffee-chicory mixture shall not be less than 0.6%, and (ii) The aqueous extract shall not be more than 50% [33].

The Bureau of Indian Standards in collaboration with the Coffee Board of India and CFTRI screened various commercial samples of chicory (Cichorium intybus) powder for chemical composition. All samples conformed to ISI specifications in respect of contents of total ash (3.5–8.0%), acid insoluble ash (max. 1.5%) and water-soluble matter (60% min.). Moisture content of 2 samples marginally exceeded the prescribed limit of 10% [34].

1.7 Tasting of coffee Coffee products are evaluated by trained and experienced tasters who have an extensive vocabulary to describe desirable and undesirable attributes of the beverages such as sweet, salty, acidic, sour, bitter, balanced, flat, stale, rancid, astringent, metallic, burnt, etc. Often flavours are described by several less well-defined terms such as brisky, cereal, chemical, earthy, grassy, green, onion, oxidized, peppery, unclean, wood, etc. Some of the important terms are discussed in the following sections [26].

1.7.1 Acidity and sourness Acidity is a desirable attribute where as sourness is undesirable, although the layman considers it synonymous. The sourness is associated with a mixture of acids, alcohols, and esters produced by microbial fermentation. Acidity is associated with protons. Wet processed, high grown C. arabica produces the


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most acid beverage; dry processed C. Robusta – the least, and dry processed C. arabica – intermediate, for a given roast and colour. Acidity is considered an important characteristic of medium roast. High acidity provides better colour and intense aroma to the beverage. It is generally agreed that pH 4.9–5.2 is the ideal range for beverage. Under ideal roasting conditions, roasted C. arabica yields a brew of the beverage in the pH range and C. Robusta yields a less acid brew of pH 5.0–5.8 [26].

1.7.2 Bitterness An element of bitterness is desirable in coffee. Bitterness has been attributed to caffeine, but even decaffeinated have been found to possess profound bitterness. It appears that other heterocyclic compounds contribute to bitterness [26].

1.7.3 Astringency Astringency is not a primary taste. Many astringent molecules are bitter, and these sensations may be confused; these are distinguished by expert tasters. Caffeoyl quinic acids, dicaffeoyl quinic acid and caffeic acid are the likely astringent components of the coffee [26].

1.7.4 Staling Staling refers to the deterioration of taste and odour on storage of coffee powder. The roasted and ground coffee preserves aroma up to 6 months under inert conditions and low temperatures. The entrapped carbon dioxide is instrumental in achieving this storage life. During storage, many volatiles decline in concentration as a result of volatility. Similarly, many new compounds are formed as a result of oxidation and other interactions [26].


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2 Health benefits

2.1 Introduction Coffee is a complex chemical mixture composed of several chemicals. It is responsible for a number of bioactivities and a number of compounds accounting for these effects. Few of the significant bioactivities documented are antioxidant activity, anticarcinogenic activity, antimutagenic activity etc. Various compounds responsible for the chemoprotective effects of coffee are mainly polyphenols, including chlorogenic acids and their degradation products. Others include caffeine, kahweol, cafestol, and other phenolics. Coffee also shows adverse effects on various systems like the skeletal (bone) system, the reproductive system, the nervous system, the cardiovascular system, the homocysteine levels, the cholesterol levels, etc. Harmful effects of coffee are associated with people who are sensitive to stimulants.

2.2 Antioxidant activity The antioxidant activity of coffee brews, using different methods of preparation was studied by Sanchez-gonaza. I, et al [35]. They observed that the antioxidant activity of coffee brews increased significantly when the brews were kept hot (80°C). The cause of this increase may be the formation of Maillard reaction in products during the heat process. These antioxidant properties are due to scavenging action of molecule for the free radical (Figure 2.1). The common antioxidant compounds in coffee are caffeine, chlorogenic acids etc. Higher antioxidant capacity was observed in Colombian conventional roasted coffee blends due to the presence of more Robusta coffee beans that contained more chlorogenic acids [36].

27


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Figure 2.1 Mechanism of scavenging of free radicals by caffeine

2.3 Anticarcinogenic activity Cavin.C, et al [37] studied the anticacinogenic properties coffee. The anticarcinogenic properties due to Cafestol, Kahweol, Caffeine and polyphenols including chlorogenic acids, and their degradation products were considered potentially responsible for the chemo-protective effects of coffee [38]. The chemo-preventive function of coffee for the anticacinogenic properties is mediated by the induction of transcription factor Nrf2. This factor is due to the coffee specific diterpenes cafestol and kahweol [39].

2.4 Central Nervous System (CNS) Coffee is an enjoyable beverage containing the alkaloid caffeine with psychotropic effects. A usual cup of coffee contains about 100 mg of caffeine. Caffeine is a strong stimulating agent of the brain cortex, respiratory and circulatory centres. Higher doses of caffeine (Single dose of 1000–1500 mg) may lead to symptoms such as trembling, anxiety, loss of mental concentration, tachycardia and sleep disorder. Coffee was known to increase alertness as seen with the central nervous system (CNS), improve performance on vigilance tasks and reduce fatigue [40]. It was known to provide a potential preventive influence of caffeine on suicide and depression. A dose dependent study showed that people consuming more than six cups of coffee/day showed a 5 fold lower risk of suicide than non-consumers [41]. Earlier, it was believed that the action of caffeine was related to the inhibition of phosphodiesterase, leading to increased concentrations of cyclic AMP. However, for the inhibition much higher doses of caffeine is required [42].


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2.5 Reproductive system Several reports attempted to determine whether women who consume caffeinecontaining beverages had any adverse effect in their reproductive system or during the developmental stage of the foetus. The results of the studies were conflicting. Since caffeine was shown to be teratogenic in animal models, safety concerns were raised regarding coffee drinking during pregnancy [43]. It is well documented that caffeine metabolism is slower in pregnant women, resulting in longer and possibly higher exposures.

2.6 Bone system The effect of coffee on bone health and calcium metabolism was studied [44]. The potential role of caffeine, mainly through coffee consumption, as a contributing factor of bone loss in humans has received a lot of attention. In recent years, numerous studies have reported a possible risk of osteoporosis on caffeine consumption.

2.7 Cardiovascular system The possible effects of coffee on cardiovascular risk factors are hypertension, elevated blood cholesterol, and, more recently, increased homocysteine levels. In a case control study, neither caffeinated nor decaffeinated coffee was associated with the risk of myocardial infarction, even for those drinking more than four cups a day [45]. There is no clear cut evidence showing any correlation between coffee consumption and myocardial infarction for moderate coffee drinkers, but the risk at the same time cannot be ruled out for high coffee consumers. Caffeine is the most widely used pharmacologic substance in the world, which is found in coffee. The effects of caffeine on cardiovascular diseases, including hypertension, remain controversial, and there is little information on its direct effect on vascular function. It is found that acute administration of caffeine augments endothelium-dependent vasodilation, in healthy young men, through an increase in nitric oxide production.

2.8 Antidiabetes effect for type-2 diabetes The diabetes type-2 is known to be caused by 11 β-hydroxysteroid dehydrogenase type-1 (11b-HSD1) activity. Epidemiological studies demonstrated a beneficial effect of coffee consumption for the prevention of type- 2 diabetes. The coffee extract corresponding to an Italian Espresso,


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inhibits recombinant and endogenous 11b-hydroxysteroid dehydrogenase type-1 (11b-HSD1) activity. Thus, coffee has the antidiabetes effect for type-2 diabetes [46].

2.9 Antimicrobial effect Antimicrobial effect may be due to the mutagenic effect of coffee on the microbes [47]. Roasted coffee was shown to possess antibacterial activity against both gram-positive and gram-negative bacteria, including Streptococcus mutans, which is considered to be a causative agent for dental caries in humans.


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3 Recent trends in value addition

3.1 Introduction Value addition is a process of development of the product from the raw materials so that the resulted product is totally different from the raw materials. The product may be new to market or an improvement of the existing one by changing ingredients (fortification enrichment) or by processing technologies. A new product is one that is unique and puts the company into a new business area, usually, as a result of new technology, innovation or consumer demand. Over the years various value-added products of coffee have been invented. Some of the value-added coffee products have been developed in order to target market segments. For this purpose various new products of coffee have been developed by different innovative ways of processing in order to explore the beneficial properties of the specific chemical components of coffee, and by mixing of compatible ingredients keeping the coffee as a base material. This has been possible due to constant research by the scientist and technologists. Because of this coffee beverage becoming the more popular than ever. The various value-added products have been described below.

3.2 Coffee beverage Beverages are defined as the liquid with some nutritional factor. In coffee beverage, water acts as a liquid medium and coffee solids function as a matrix. During the brewing process coffee solids are extracted into the liquid system. The extraction takes place by means of leaching from coffee roasted and ground powder. The various methods of preparation of coffee beverages are decoction, infusion and pressure methods [48].

3.2.1 Boiled coffee The coffee soluble solid is kept in contact with given amount of water at appropriate temperature for a considerable time period. The extraction takes place by the law of mass action. Higher temperature favours the higher extraction yield and rate.

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Prolonged extraction may cause unfavourable flavour and taste. This is due to the loss of volatiles and hydrolytic changes. Taste of the coffee is much better, if the boiled water is added to the ground coffee. The coarse- ground coffee is put in the water in a pot or jug and allowed to warm up to the boiling point, and then brew is collected as boiled coffee [48]. Boiled coffee consumption increases the blood cholesterol, since it contain considerable amount of suspended solid and is ingested along with the liquid. These contain insoluble diterpene, viz. cafestol which acts as a blood cholesterol up regulator. A simple filtering step through filter paper is enough to remove this fraction [49].

3.2.2 Turkish coffee The coffee is ground into very fine particle to increase surface area. Special equipment, viz. ibrik ( Figure 3.1) is loaded with ground coffee along with sugar. Then, it is filled with cold water and placed on an open flame. After reaching the ebullition temperature, revealed by vigorous foaming, the pot is removed from the flame and allowed to cool down and then replaced on the flame to a second time and there after third boiling. Then, the ibrik’s liquid content is collected. This method is popular in all the Mediterranean countries [48].

Figure 3.1 Turkish coffee

3.2.3 Percolator coffee During the extraction process the coffee brew is recycled several times along with the heating in percolator. Repeated circulation results more enriched


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coffee brew, exploiting the ground coffee completely. The beverage is harsh and unpleasant taste, along with the loss of aroma volatile compounds. Brewing of coffee in the aluminium percolator found to increase the aluminium content in the brew with the time of storage [50].

3.2.4 Vacuum coffee This coffee beverage is prepared in a special type of equipment consisting of two flasks – top flask and bottom flask. The top one is funnel-shaped glass flask with perforated screen. The ground coffee is placed on the perforated screen and water in the bottom flask. The assembly of the two vessels is heated up to boiling. Because of the steam pressure, the hot water forced into the upper vessel and mixes with the ground coffee and results in extraction. After the heat source is removed, the assembly is allowed to cool down until the pressure in the lower flask is reduced. The pressure is low enough to allow the upper liquid to flow down through the same funnel neck. The coffee beverage is served directly from the lower bowl. The commercial model of this equipment is called Cona [48].

3.2.5 Filter coffee The pulverized coffee is boiled in hot water for a short time. The hot water flows through partially soluble coffee bed continuously at a constant temperature between 80°C and 100°C. Due to the shorter contact time, the infused beverages are milder, enhanced acidity and more flavoured than the decocted ones. The typical set up for filter coffee consists of a simple device, where a filter paper is placed in a plastic cone-shaped holder. Medium ground coffee is put into the filter and the holder is placed on the top of a glass jug. Boiled water is then poured into the filter and allowed to steep through. This coffee is also known as drip coffee. Now many automatic or semi-automatic machines are available. The hot water drips at a controlled rate on the ground coffee for proper infusion. The machines are called drip coffee machines [48].

3.2.6 Napoletana coffee The instrument for this type of coffee is called macchinetta napoletana and is also known as flip drip pot. Gravity makes hot water to percolate through a bed of medium-coarse ground coffee. A pot, on top of which a perforated bushel contains the ground coffee, filled with water and heated indirectly by flames. After reaching the boiling point, the macchinetta is removed from the heat and turned upside down, allowing hot water to drip through the coffee into the second-half of the device. The main mechanical difference between drip filter and Napoletana method is that in the latter the ground coffee is immobilized


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between two filtering perforated plates, preventing the movement of the granules in the water. The water is flowing through the coffee and is not swing within the water. During the heating of water, the steam comes in contact with ground coffee and results scalding of coffee and causes bitterness in it [48].

3.2.7 Espresso brewing Espresso in Italian language means prepared at present or at this very moment. The coffee prepared by the espresso method could be immediately consumed soon after preparation relishing all the aroma and flavour of freshly ground and brewed coffee [48,51]. The espresso coffee beverage is a polyphase colloidal system, in which the liquid phase is topped by a wet foam of tiny sphereshaped gas bubbles. Each sphere is surrounded by a liquid film (lamellae) that separates it from its neighbours and hosts biopolymers and natural surfactants. Foaming biopolymers of coffee (proteins/melanoidins fraction and polysaccharides fraction) were extracted from defatted and roasted ground coffee [52]. Espresso coffee beverage is prepared from the roasted and ground coffee beans, by means of hot water pressure applied for a short time to a compact roast and ground cake by a percolation machine. Pressure is applied for the percolation of water through the ground coffee. Due to the driving force of pressure, the micron-sized solid particles and oil droplet goes along with coffee brew. This may change the beverage properties dramatically, enhancing the sensory characters [48]. Quantity of ground coffee and the parameters for a cup of espresso coffee beverage are as follows: • • • •

Ground coffee Water temperature Inlet water pressure Percolation time

- 6.5±1.5 g - 90±5°C - 9±2 bar - 30±5 s

The key role in espresso method is played by pressure. The pressure is transformed into kinetic energy. Some part of kinetic energy is transformed into the surface potential energy and partly into heat energy. This energy substantially modified the behaviour of ground coffee undergoing extraction. The external appearance and organoleptic character of beverage differs from the other methods of preparing coffee beverages. The liquid is crowned with an abundant layer of compact foam. This forms the oil in emulsion [51]. The peculiar organoleptic properties are due to the non-hydro soluble substances which are absent in the other methods of brewing. The emulsion of the liquid droplet imparts espresso its peculiar texture taste and mouth feel. Milk with little cream and sugar are added to taste. Espresso can also be taken with flavours like chocolate, cardamom and clove.


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The use of sophisticated machinery and technology enhances the visual olfactive and gustative characteristics of coffee beverage. In fact, maximum aroma can obtained with the espresso method due to the presence of essential oils, various colloidal substances and other noble components. Another advantage of espresso coffee is the drastic reduction of caffeine in the cup compared to the other methods of coffee brewing due to its short percolating time. It is estimated that the caffeine content of cup of espresso coffee is in between 60 and 120 mg while the content ranges from 150 to 300 mg per cup of coffee brewed employing other traditional method. Four important factors responsible for the preparation of espresso coffee are generally recognized as 4 M factors [51], which are as follows: • • • •

Miscella (blend) Macinino (coffee grinder) Maccihina espresso (espressomachin) Mano (hand of the operator)

Miscella (Blend) A good single variety of coffee may contain some deficiencies, which are to be complimented with a balanced combination of other varieties to even out the deficiencies and at the same time for enhancing the organoleptic qualities. The formulation of the different blends for espresso coffee is usually entrusted with a cup taster. A cup taster looks at the presence and combination of different characteristics like colour, body, sweetness, acidity, bitterness and a very intense aroma in different coffees while preparing blends for espresso machines. In the espresso type of coffee brewing, the colour of the final brew and the thick persistent foam or cream is having commercial importance. The foam acts as an aroma sealing cover and preserves the aroma and volatile oils. If the blends prepared by the cup taster are totally composed of Arabica then the colour of the espresso coffee liquor is deep hazel with reddish shades and with more thick and persistent cream. If the coffee is browner with greyish shades, less compact and less persistent cream, then the blend must be composed totally or dominant of Robusta coffees. These Robusta blends are less aromatic and bitter in taste.

(Macinino) Coffee grinder In the method of espresso coffee preparation, incorrect use of the coffee grinder can strongly affect the quality of coffee. If the hopper of the coffee grinder is kept unclean, the taste of rancid oils can be detected in the cup. Poor cleaning


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of dispenser outlet causes powder to become rancid and interfere with the doser, dispensing the right quantity. To avoid staleness in the espresso cup, minimum amount of coffee powder is kept in the dispenser and in the grinder, just enough for 30 min consumption. It is also important that during grinding the temperature should not exceed 40–50°C. A temperature of more than 50°C will burn the components of the ground coffee and impoverish the cup of espresso coffee, which will become harsher, bitter and certainly less aromatic. In the espresso preparation, the grain size of coffee powder is very important. Generally, fine grind is preferred for espresso coffee preparation. The roasted coffee beans should ground according to the prevailing atmospheric humidity. If the humidity is high, slightly coarser grind is required, and if humidity is low, finer grind is required. If the grain size is coarser, the machine will produce under extracted coffee and when the grain size is over fine the machine will produce over extracted coffee.

Maccihina Espresso ( Espresso machine) The function of espresso machine is to provide energy, i.e. heat and pressure to the water, enabling it to pass through the fine coffee powder swiftly so as to extract its best qualities. The heat around 92°C [53] and the pressure of 9–10 bars are provided by hot water in the boiler and electro magnetic pump respectively. The espresso machine consists of following components. • • • • •

Gas or electricity (source of heat) Exchanger (hot water element) Pump Hot water tap Control instruments

(Mano) Hand of the operator The 4th “M” corresponds to the Mano which is the hand of the operator. Today, with the use of the modern and fully automated espresso machines the word ‘Mano’ can be changed into ‘Mente’, which means the mind of operator. In the most advanced and complicated models of espresso machines, the instruments are provided with functions like measure consumption, checking cleanliness, and wear and tear. Naturally, an operator of these machines is required to use more of his mind than his hand. Perfect application of all the four “M” factors give a perfect espresso coffee which must have a compact, fine grained long lasting cream/foam and a fine button hole. The foam must be persistent, long lasting and 3–4 mm thick.


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Colours vary from deep hazel to dark brown with reddish shades and light hazel streaks. Taste must be sweet with slight acidity, a pinch of bitterness, chocolate like taste, intense aroma and pleasant after taste [51].

3.3 Canned coffee beverages Pre-brewed canned coffee beverage is a convenient product, where right brewing equipment is not available. The pleasure of the canned coffee is not as good as that of the fresh one. Pre-brewed coffee is filled in cans and subjected to sterilization, pasteurization, etc. Prolonged heating of coffee causes taste deterioration due to degradation products of acids [54].

3.4 Ready-mix coffee beverage All the ingredients in this coffee beverage are in the dry form. The soluble coffee, milk powder and sugar are mixed in the proportion 1:5:10. For getting homogeneous mixture, all the ingredients are thoroughly mixed. The particle size of all the ingredients should be uniform. This coffee beverage is highly hygroscopic in nature, so the packaging material possesses barrier properties to both oxygen and moisture. Shelf-life is very short (~10 days). However, shelf- life of the coffee ready mix is enhanced through vacuum packaging or inert gas packaging. About 25 g of the mix are needed for a cup (8 oz) of coffee [55].

3.5 Coffee–milk admixture

In coffee–milk admixture, the milk adjusts or masks the objectionable flavour of the coffee brew. The milk fat emulsions maintain the aroma balance of coffee brew. The milk fat improves the appearance, texture and after-taste persistence of coffee drink. The protein and fat contents in milk are critical to the foam development. Skimmed milk contains the greatest percentage of the protein, and foams better than the low fat or whole milk. The fat content in the milk helps to keep the foam stable [48]. Milk proteins (casein and whey proteins) and milk fat influence the release of flavour compounds from white coffee beverage in the oral cavity. For this reason a retro-nasal headspace technique for measurement of the flavour was adapted. A gas sampler equipped with a mouthpiece was used as an Oral Breath Sampler (OBS). Analyses were performed by gas chromatography with mass spectrometric detection. It was noticed that the sampling at different hours resulted in different standard deviations. The flavour release is more constant in the morning (Variation coefficient from 3% to 28%; median: 10%) than in the afternoon (7–52%; median: 23%). The relationships between flavour release and some salivary


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parameters like salivation rate, buffer capability and protein content were also studied. The Oral Breath Sampling was considered to be a valuable sampling method for the analysis of the retro-nasal aroma release from coffee beverages [56].

3.6 Coffee jelly beverage Coffee jelly beverage (Figure 3.2) is prepared by regulating a solution containing coffee and jellying agent at a pH less than 4.0 using acid. The acidifier may be either of phosphoric acid, gluconic acid or phytic acid. Generally, phosphoric acid is chosen. The amount of sugar required is in the range of 0.1–20% by weight. After preparation of solution, it is subjected to sterilisation process at a temperature of 65–100°C [57].

Figure 3.2 Coffee jelly beverage

3.7 Fortified coffee beverages Iron-fortified soluble coffee is prepared in two steps, viz. precipitation of polyhydroxyphenols and polyhydroxyphenol-polysaccharides from the coffee extract at 2–20°C; addition of an assimilable elemental iron at the rate of 0.01–1% by weight of coffee solids. Liquid coffee extract having a solid concentration of about 10–30% was maintained at a temperature below about 70°F for a period of time sufficient to precipitate the components which interact with elemental iron. Then, the extract was clarified and fortified with nutritive ingredients including a soluble iron compound containing assimilable iron, and then dried by freeze drying [58].


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3.8 Fortified coffee drink A soluble powder that produces a low-fat coffee beverage fortified with vitamins and minerals when reconstituted with water is described. The powder consists of an instant coffee component, a protein component, a vitamin/mineral component which provides greater than or equal to 25% of the United States Recommended Daily Intake (US RDI) per 8 oz serving, and a carbohydrate component which provides approximately 140 cal/8 oz serving [59].

3.9 Honeyed coffee Honey coffee is prepared from dry de-pulped coffee beans. The coffee beans are dried as such along with the parchment and mucilage on a perforated conveyer over a period of 1–20 days. During the process of drying, the sweetness in coffee increases since the coffee beans absorb water, sugars and other constituents from the mucilage by capillary processes. Further processing is done as per the conventional method [60].

3.10 Coffee tablet Kaku and Chandler developed a process for the preparation of coffee tablet [61]. The roasted coffee is compressed in a roller press (briquette press) to form a tablet which is then crushed to provide and agglomerate, and later introduced into a sachet for beverage preparation. In an alternate method, coffee tablet is prepared by mixing ground coffee with hydrophilic substance. The hydrophilic substances absorb water. Then the mixture is compressed into tablet form. The tablet is used in preparation of coffee drink [62]. Coffee tablets with integrated aroma are obtained by combining the dry instant coffee with roast coffee aroma concentrate. The coffee tablet is packaged in retail containers similar to those used for pharmaceutical tablets [63].

3.11 Freeze-dried coffee tablets The freeze-dried coffee tablet is used in beverage preparation. These tablets are prepared through moulding and freeze-drying a solution of coffee solids into a desired shape. It has improved solubility, a smooth surface and porous nature in which most of the pores are interconnected, and are between 10 and 50 µ in size. A coating can also be added to the tablet containing coffee flavourings, colourants or aroma compounds. The coffee tablet is packaged in an aroma-filled environment, leading to a product that exhibits fresh, strong flavour and aroma upon beverage preparation, even after long-term storage [64].


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3.12 Flavoured coffee 3.12.1 Cerelac flavoured with instant coffee Instant coffee is added to the cerelac (nutritious food for health and growth) by physical mixing. Composition, microbiological quality and sensory quality are compared with those of the original product of cerelac. Coffee flavoured with cerelac showed high sensory quality and acceptance; composition and microbiological quality are similar to those of the original type of cerelac [65].

3.12.2 Flavoured coffee paste Flavoured coffee paste is prepared by mixing of the concentrated coffee extract with pulverized coffee bean. The average size of the pulverized coffee grain is about 30–50 µ [66].

3.12.3 Yoghurts flavoured with instant coffee Yoghurts are flavoured with instant coffee at concentration of 0.5%, 0.7% and 0.9%, and sweetened with sugar (4 or 5%). Physicochemical, microbiological and sensory properties of experimental yoghurts are compared with those of control yoghurt (no coffee or sugar). It is found that the added ingredients generally have no effect on the chemical, physical and microbiological quality of yoghurts initially as compared to the control. During 15 days storage at 57°C, pH and lactic acid bacteria counts decreased and titratable acidity increased in all samples. Yoghurts with 0.5% coffee flavouring and 4 or 5% sugar met Turkish Institute Standards for yoghurt sensory quality when evaluated by a trained 10-member panel. Yoghurt flavoured with 0.5% coffee as well as 5% sugar possessed most attributes rated in the 'like' category by 50% or more of consumer panellists [67].

3.12.4 Flavoured coffee beverage Coffee can be flavoured with vanilla nut, Irish cream, chocolate, vanilla, macadamia nut, chocolate almond, coconut, cinnamon and chocolate raspberry cream. The flavouring substances are used either in a liquid form or in a powder form. The key operation is thorough mixing of the liquid additive with whole roasted beans or powder flavouring agent with ground coffee. The flavouring agent is mixed at 2% concentration. The new way of flavouring the coffee beverage is by directly putting the flavour-coated stirrer into the cup. During the agitation, the flavoured ingredients are released from the stirrer to make flavoured coffee [48].


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3.13 Coffee wine Coffee wine is prepared using a wine-making procedure. Brewed wines are manufactured from Cavita coffee beans. Wines are fermented in polycarbonate plastics containers, rather than wooden barrels, in order to avoid methanol formation. Boiling and filtration stages are carried out to ensure high quality wine. Distillation is avoided in order to preserve natural flavour of the raw material. Wines obtained are free from methanol and contain an ethanol content of about 12.5% [68].

3.14 Candy from coffee beans The coffee beans are roasted at 200–270°C in a fluidised bed using a mixture of steam and coffee roasting gases. After roasting for 70–200 s, crystalline sugar or sugar solution (2–4 g sugar per gram of water) are finely dispersed onto the fluidised bed. The sugar dries and caramelises on the surface of the coffee beans to form a uniform layer over each coffee bean. The coffee beans, still fluidised, are then cooled to 10–60°C with ambient air over a period of 110–400 s. Cooling may take place in 2 stages. The preliminary cooling to set the candied sugar coating so the coffee beans do not stick together and followed by final cooling [69].

3.15 Torrefacto coffee Torrefacto coffee is prepared by the coating of roasted coffee beans with caramelised sugar. Green coffee beans are roasted, cooled and coated with caramelised sugar (in aqueous solution) to give a caramelised sugar content of 5–15% by weight. The finished product may be marketed as whole or ground coffee beans [59].

3.16 Germinated coffee Germinated coffee contains good balance of nutrients particularly, amino acids and it possesses a mild flavour. It may be used in both beverages and processed foods. Fresh coffee beans are immersed in water at a temperature of 5–50°C until they absorb the water required for germination. Water (20–40°C) is sprayed during germination process to avoid drying. After germination, these are washed with water to remove extraneous matter and dried until their water content is reduced to approximately 11% or below. The germinated coffee beans are stored and distributed like fresh coffee beans [70].


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3.17 Coffee filled packet Coffee bean particles are filled in the water permeable packet. The packet size should fit between the cheek and gum. This packet is directly placed into the mouth. This type of packet is used when an individual is away from civilization or has no access to hot water or a coffee maker [71].

3.18 Cookie formulation with coffee Three varieties of cookie are formulated using coffee as espresso beverage, instant coffee and roasted coffee powder. The average proximate composition (dry basis) of the formulation is 70% carbohydrates, 8% protein, 21% fat and 1% minerals. The average calorific value of each formulation is 499 kcal/100 g products. Both the proximate composition and average calorific value is similar to the values reported for existing commercial brands of cookies. The sensory properties (flavour and texture) of cookies are influenced by the way in which coffee is added to formulation. The formulation employing the espresso beverage is presented in lower values for cracking, crumbling, presence of dark spots and coffee as well as burnt flavour. The product manufactured using the instant coffee powder exhibited higher values for brown colour intensity, shine, coffee as well as burnt flavour along with residual brown sugar flavour and crunchiness, and lower values for concavity. Samples made with roasted coffee powder displayed higher values for the presence of dark spots. All three formulations showed satisfactory acceptance levels when assessed [72].

3.19 Coating of frozen pizza with coffee colorant Microwave processed pizza involved coating of the outer edge of the pizza crust with an aqueous colouring solution, containing an edible dispersion agent and a natural colorant such as coffee [73].

3.20 Carbonated coffee It is sparkling carbonated beverage containing coffee brew, sugar, acid, carbon dioxide and preservatives. Its preparation consists of mixing of sugar syrup, coffee brew, acids, preservatives followed by dilution and carbonation. It is best enjoyed as a chilled beverage. It is possible to replace the coffee brew with soluble coffee powder. Because of coffee aroma, it is called coffee flavoured novel beverage. This beverage is also flavoured with chocolate, cardamom, vanilla for better value addition. It has shelf-life like that of any other soft drink [12].


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3.21 Decaffeinated coffee Caffeine present in coffee is responsible for most of the physiological effects of the beverage. Selected people do not tolerate caffeine. It stimulates the central nervous system, shows toxicity when fed in excess and is even mutagenic in vitro [74, 75]. It can cause excessive influence on the central nervous system and respiratory system. The symptoms are restlessness, excitement and insomnia. Excessive consumption of caffeine through beverages is associated with a number of health problems like adrenal stimulation, irregular muscular activity [76,77), cardiac arrhythmias [78] and increased heart output. Excess caffeine is reported to cause mutation, inhibition of DNA repairs and inhibition of adenosine monophosphodiesterase [79], and during pregnancy causes malformation of foetus and may reduce fertility rates [80]. The various decaffeination processes are presented in Fig. 3.3. Green coffee beans Water

Wet beans

Solvent

Water

Solvent rich Decaffeinated beans in caffeine wet beans Solvent Caffeine

Solvent removal

Caffeine rich extract

Super critical CO2

Decaffeinated wet beans Drying

Decaffeinated wet Drying

Caffeine

Decaffeinated coffee beans Figure 3.3 Various decaffeination processes of coffee

Decaffeination of coffee is reported using organic solvent, water and super critical carbon dioxide, and biological method [81]. The impact of the water decaffeination process on chlorogenic acid (CGA) and chlorogenic gammaquinolactones (CGL) levels of green and roasted arabica coffees was evaluated


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[82]. Decaffeination produced on an average a 16% increase in the levels of total CGA in green coffee. In this process, water is used as the extracting solvent and extraction is carried out at about 90–95°C. Super critical carbon dioxide method of decaffeination of coffee was studied by [83]. Under high pressure, carbon dioxide gas acts like a fluid and can be used as a solvent and decaffeination of coffee beans is done. Studies on the degradation of caffeine were carried out using a strain of Pseudomonas alcaligenes CFR 1708, isolated from coffee plantation soil [84]. Gokulakrishnan et al reported that the different microbial and enzymatic methods of caffeine removal [85]. The literature revealed that major caffeine degrading strains belong to Pseudomonas and Aspergillus.

3.22 Soluble coffee Soluble coffee is ready in an instant. It is transportable and has a long shelflife. Value-added soluble coffee products such as iced coffee and flavoured cappuccinos are popular in convenience stores. Many consumers use it by choice as a quick caffeine fix in the morning [86]. Instant coffee spoils fast if it is not kept dry. Instant coffee differs in make-up and taste to ground coffee. In particular, the percentage of caffeine in instant coffee is less, and bitter flavour components are more evident. Bel-Rhlid describes the method for reduction of the bitterness in soluble coffee [87]. The lowest quality coffee beans are often used in the production of soluble coffee. Silver and Whalen describes enzyme-assisted soluble coffee production [88]. The method for producing the soluble coffee involves combining roast and ground coffee with water, adding hydrolase enzymes, wet-milling to a mean particle size of approximately 10–250 µ,treating the reaction mixture at a temperature of approximately 50–60°C, and circulating the reaction mixture through a crossflow, semi-permeable membrane separation device to yield a soluble coffee extract. Sediments are a major problem in the instant coffee preparation. This problem is due to the galactomanon fraction of polysaccharides. This problem can be solved by enzymatic hydrolysis during the extraction processes of soluble coffee fraction. The highest sediment reduction was obtained using Rophapect and Galactomannanase at concentrations of 0.3 and 0.1 mg protein per gram substrate, respectively [89]. The fundamental steps of soluble coffee preparation are shown in the Fig. 3.4. Boss et al optimised the temperature and time for the freeze drying of soluble concentrate [90]. The biggest problem is the time of drying, since the longer the time, higher are the energy costs. Because of this, the goal function is to minimize the drying time for the soluble concentrate of coffee. However, it is found that the actual industrial processing takes much more time with less


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removal of water compared to the optimised time of processing. Further, it was reported that retention of water in the real industrial data is more than the optimised data against the time. The optimisation of the freeze drying process is a tool of extreme importance which should be used to decrease the processing time as well as to decrease the cost of the process. It is also observed that the process is very sensitive and small alterations in suitable variables may allow the process to be operated with larger efficiency and productivity. Green coffee beans

Roasting

Grinding

Blending

Extraction

Concentration

Drying and agglomeration Aroma Soluble coffee

Figure 3.4 Conversion of green coffee into soluble coffee

3.23 Instant hot cappuccino Dry mix instant hot cappuccino coffees consist of water-soluble coffee, a foam generator, an optional cream and an optional sweetener. The foam-


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generating component comprises gluconolactone and an alkali metal carbonate or bicarbonate. Cappuccino beverages are prepared by mixing a liquid component and the dry mix composition and heating. A good quality cappuccino is produced with either dairy or non-dairy creamer. With dairy creamers, the formation of floating white aggregates on the surface of the beverage is avoided. Cappuccino coffee is prepared from the espresso coffee beverage. For the preparation of the cappuccino dry-mix, foaming creamer composition comprising a particulate protein component in an amount from 1 to 30%, a foam-generating carbohydrate (a bulk density of less than 0.3 g/cc) in an amount of 20–90% and a lipid in an amount of 0–30% are taken [91].

3.24 Monsoon coffee Monsooning of coffee beans is a flavour induction process employed in India, where coffee beans are exposed to moist monsoon winds in open warehouses. Monsooned coffee is prepared in west coast of India during monsoon season. The varieties used in preparation of monsoon coffee are AA and AB grades of arabica and Robusta. The beans are exposed to a humid atmosphere causing them to absorb moisture upto 15–16%. The green coffee is spread in wellventilated brick-floored warehouses to a thickness of 4–6 inches during the monsoon season. The coffee beans are raked periodically and exposed to humid atmosphere for periods ranging from 6 to 8 weeks. These are packed in loosely woven gunny bags, stacked, bulked and re-bagged. This result in swelling to one-and-half times the normal size of cherry beans and a change in colour to pale white or golden/light brown. These swollen beans are then polished through hullers, graded and garbled by sorter. Through monsooning, the dry-processed coffee acquires a special natural mellow flavour. Monsooned Arabica / Monsooned AA and Monsooned Robusta AA are in great demand in the international market. Indian monsooned coffee is mainly exported to Europe [92].

3.24.1 Flavour compounds in monsooned coffee Volatile aroma principles, non-volatile flavour compounds (caffeine, and chlorogenic and caffeic acids), and glycosidically bound aroma compounds of monsooned and non-monsooned raw arabica coffee were analysed using GC-MS and HPLC. The most potent odour-active constituents known to contribute to the aroma of the green beans are 3-isopropyl-2-methoxypyrazine, 3-isobutyl-2-methoxypyrazine, 4-vinylguaiacol, beta-damascenone, (E)-2nonenal, trans-2, 4-decadienal, phenylacetaldehyde and 3-methylbutyric acid. A decrease in content of methoxypyrazines and an increase in 4-vinylguaiacol and isoeugenol resulted in a dominant spicy note of monsooned coffee.


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These phenols exist partly as their glycosides and their release from the bound precursors during monsooning accounted for their higher content in monsooned coffee. A considerable decrease in astringent chlorogenic acid as a consequence of hydrolysis to bitter caffeic acid was noted in monsooned coffee [93].

3.24.2 Impact of gamma irradiation on the monsooning of coffee beans High-moisture content during monsooning process favours the growth of microorganisms on coffee beans, which affects the product quality. Coffee beans (Arabica and Robusta varieties) were subjected to gamma-irradiation at 5 and 10 kGy doses. Both treatment doses reduced populations of natural mycoflora on beans with a greater effect observed at 10 kGy. Prior to monsooning, Aspergillus niger was the predominant fungal species on coffee beans however, A. ochraceus became the dominant species during monsooning. Other Aspergillus spp., Penicillium spp., Absidia spp., Syncephalastrum spp., Mucor spp. and Rhizopus spp. were also identified in samples, in much lower numbers. During monsooning, fungal growth occurred at a lower rate on gammairradiated samples compared with non-irradiated samples. Monsooning time was substantially reduced by gamma-irradiation; completion of monsooning took 5 weeks in non-irradiated samples, compared with 2 weeks for samples subjected to gamma-irradiation [94]. Radiation processing of non-monsooned beans at a dose of 5 kGy resulted in an increased rate of monsooning. At this dose, a quantitative increase in most of the aroma active components could be observed in all samples studied. Hydrolysis of chlorogenic acid to caffeic acid was noted in radiationprocessed monsooned coffee beans irrespective of whether the treatment was carried out before or after monsooning [93].

3.25 Coffee paste This is a ready-to-serve coffee beverage in highly concentrated form. The liquid ingredients, milk and coffee brew are separately concentrated, mixed with sugar thoroughly to obtain the product in a paste form. During the extraction of coffee powder, the aroma rich initial extract is collected separately and mixed with the concentrated milk and brew in the end. This product is best canned and stored under refrigerated conditions. Consumer (unit) packs can be made in aluminium-foil-laminated pouches [13].


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4 Value-added by-products

4.1 Introduction The waste products from the coffee industries consist of silver skin, parchment, mucilage, pulp, etc. In the conventional way these are utilised for the production of the manure, compost, fertilizer and live stock feed. However, these applications utilise only a fraction of available quantity and are not technically very efficient. Using the recent technologies, value added products can be obtained from coffee industry waste which is much more economical than the conventional method of utilising the coffee waste. Byproducts from coffee processing are presented in Fig. 4.1. Advances in industrial biotechnology offer potential opportunities for the economic utilisation of agro-industrial residues such as coffee pulp and coffee husk. Coffee pulp or husk is a fibrous mucilaginous material, obtained during the processing of coffee cherries by wet or dry process respectively. Coffee pulp/ husk contain some amount of caffeine and tannins, which makes it toxic in nature, resulting in the disposal problem. However, it is rich in organic compounds, which makes it an ideal substrate for microbial processes for the production of value-added products. Several solutions and alternative uses of the coffee pulp and husk have been attempted. These include fertilizers, livestock feed, compost, etc. However, these applications utilise only a fraction of available quantity and are not technically very efficient. Attempts have been made to detoxify for improved application as feed, and to produce several products such as enzymes, organic acids, flavour and aroma compounds, mushrooms etc, from coffee pulp/husk. Solid-state fermentation has been mostly employed for bio-conversion processes [95].

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Recent Trends in Soft Beverages Coffee cherries

Dry process

Washing

Wet process

Drying

De-pulping

Cleaning

Coffee pulp

De-hulling

Mucilage

Fermentation Washing

Selection Hulls

Packing

De-hulling Drying

Quality coffee

Coffee husk

Packing Quality coffee

Figure 4.1 Industrial processing of coffee and coffee by-products

4.2 Source of dietary fibre Coffee is a major food commodity, therefore coffee by-products are amply available. The coffee silver skin (CS) is a tegument of coffee beans that constitutes a by-product of the roasting procedure. The process of obtaining the silver skin from coffee is presented in Fig 4.2. The coffee silver skin can be used as potential source for the dietary fibre, antioxidative activity and prebiotic activity [96].

4.3 Coffee spirit Bodmer and Ruder developed a process for the production of spirit (alcohol ≤ 20%) from the coffee cherries [97]. The flesh of the coffee cherries is separated


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Value-added by-products

and is subjected to the fermentation process by adding sugar. The fermented material is subjected to distillation processes for separating the alcohol. The distillate can be used for the drinking after dilution. Coffee cherries Mechanical removal

Outer skin and pulp Mucilaginous parchment beans

Fermentation

Remaining mucila ge

Parchment beans Drying dehulling

Parchment hulls Raw beans

Roasting

Coffee silver skin Roasted coffee beans

Figure 4.2 Production of silver skin (CS) from wet processing of coffee

4.4 Charcoal production Charcoal is produced from the dried coffee bean residues using carbonisation process. The carbonisation process is done at higher temperature of 800, 1000 or 1200°C. The prepared charcoal is sieved, washed and dried. Charcoal from waste coffee ground is a very useful source for the removal of acidic dye. The charcoal from the spent coffee can be used for the decolourisation of acidic dye, viz. acid orange 7 [98].

4.5 Mushroom cultivation Industrial coffee wastes such as coffee husk and spent coffee ground are used for the production of Pleurotus ostreatus by the solid-state fermentation (SSF). Coffee pulp is a substrate component for Pleurotus ostreatus production [99]. Using coffee husk and spent coffee ground as substrates without pre-treatment for cultivation of an edible fungus in SSF, provides a better step towards the utilisation [100].


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4.6 Production of citric acid and gibberellic acid Citric acid is produced from the coffee husk by the processes of SSF, using the Aspergillus niger CFTRI 30 strain as the culture. This strain produces 1.3 g citric acid per 10 g of dry coffee husk in 72-h solid-state fermentation. Production is increased by 17% by adding a mixture of iron, copper and zinc to the medium. The sugar conversion rate is 84%. Hence, the coffee husk is the potential source for the production of citric acid [101]. Machado et al reported that the production of gibberellins (plant hormones) in submerged fermentation (SmF) and SSF, utilising coffee husk as the carbon source [102]. Five strains of Gibberella fujikuroi and one of its imperfect state, Fusarium moniliforme, were used for comparison. Results showed the production of gibberellic acid (GA3) in all the fermented samples. SSF appeared superior to SmF.

4.7 Antioxidant compounds Yen et al evaluated the antioxidant activity of roasted coffee spent residues, in different in vitro model systems [103]. The coffee spent residues have excellent potential for use as a natural antioxidant source because the antioxidant compounds remain in roasted coffee residues. The antioxidant activity of spent coffee residues may be due to the presence of phenoloic compounds such as chlorogenic acid and caffeic acid.

4.8 Source of natural food colour The anthocyanin content and profile of fresh coffee husks (outer skin and pulp) were analysed. Cyanidin 3-rutinoside was the major anthocyanin encountered in the extracts, followed by a small amount of cyanidin 3-glycoside. Thus, the fresh coffee husk can be used as potential source of natural food colour [104].

4.9 Production of aroma compounds A novel approach on value addition of coffee husk is to use it as a substrate for the production of aroma compounds for food industry application with yeast and fungi. Soares et al used the yeast Pachysolen tannophilus in SSF for synthesizing aroma compounds, using coffee husk as a medium. The yeast culture produced a strong alcoholic aroma with fruity flavour. Along with ethanol, which was the major compound produced, acetaldehyde, ethyl acetate, isobutanol, isobutyl acetate, ethyl-3-hexanoate and isoamyl acetate


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Value-added by-products

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were also produced by the culture, giving a strong pineapple aroma. When leucine was added to the medium, a strong banana odour was found with increased amounts of isoamyl alcohol and isoamyl acetate [95].

4.10 Biogas production Attempts have been made to use coffee industry residues, mainly coffee pulp and husk for biogas production in anaerobic digestion. According to the estimates, from one ton of coffee pulp, about 131 m3 biogas could be produced by anaerobic digestion which would be equivalent to 100 l of petrol in fuel value. Robusta and arabica coffee solid residues generate about 650 and 730 m3 methane per ton of solids, respectively [95].

4.11 Source of phenolic compounds Agro-industrial by-products are a potential source of value added phenolic acids, with promising applications in the food and pharmaceutical industries. Two purified forms of feruloyl esterases from Aspergillus niger, Feruloyl Esterases A and Feruloyl Esterases B, were tested for their ability to release phenolic acids such as caffeic acid, p-coumaric acid and ferulic acid from the coffee pulp. Feruloyl esterase B is a potential source for releasing of phenolic compound from the coffee pulp [105].

4.12 Summary and conclusion The major coffee-producing countries are Brazil, Vietnam, Columbia, Indonesia, Ethiopia, India, Guatemala, Mexico, etc. Among these, Brazil is first in the production and India is at 6th position in production. India accounts for about 4% of world coffee production. Main importing countries of Indian coffee are Italy, Germany, Russian federation, Spain, Belgium, Slovenia, USA, Japan, Greece, Netherlands and France. The fruit of coffee is called berry. It consists of the two flat-shaped coffee beans. The bean is surrounded by silverskin, pulp and outer skin. The bean is made up of the endosperm, which is the commercial edible part. Coffee fruits are processed for the production of parchment coffee and cherry coffee beans. The parchment coffee is prepared by wet processing method and the cherry coffee is prepared by dry processing method. The green coffee is further subjected to processing for the production of the coffee roast and the coffee ground. Roasting is the most important step in the coffee processing. It provides the unique characteristics of the coffee such as physical and the chemical properties. Utmost care is taken for the production of the good coffee product during the roasting.


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Coffee contains a complex mixture of chemical compounds. Substances that dissolve in water to form the beverage during brewing are classified as nonvolatile components (viz., caffeine, trigonelline, chlorogenic acid, phenolic acids, amino acids, carbohydrates, and minerals) and volatile components. Volatile aroma components include organic acids, aldehydes, ketones, esters, amines, and mercaptans. The aroma related to the aroma chemicals are produced during roasting of the green beans. It is generally accepted that caffeine is responsible for many of its physiological effects. Caffeine influences the central nervous system in a number of ways mainly it enhances alertness, concentration, and mental and physical performance. Coffee has been enjoyed as a drink by millions of people worldwide for over at least one thousand years. The various value-added products that obtained from the coffee are boiled coffee, turkish coffee, vacuum coffee, filter coffee, espresso coffee, canned coffee beverages, ready mix coffee beverage, coffee–milk admixture, coffee jelly beverage, fortified coffee beverages, fortified coffee drink, honeyed coffee, flavoured coffee, coffee wine, candy coffee, torrefacto coffee, germinated coffee, cookie formulation with coffee, carbonated coffee, decaffeinated coffee, instant hot cappuccino, monsoon coffee, Instant coffee etc. Each value-added product has its own speciality in terms of preparation and quality. There are many value added products are available in the market. The consumer acceptance to value added products is ever increasing. The consumer preference changes as the time passes. So continuous research, regarding the value addition to the coffee has to be kept on alert for developing further the new coffee value added products. Lastly, any industry in order to maximize the profits and maintain the environmental policy, they are converting the industrial waste into the suitable value added by-products. Value addition to the coffee waste is done through biotechnological processes. Now many biotechnological processes have been developed for the production of the value added products from the coffee waste. The various value added products that obtained from the coffee waste are dietary fibre, coffee spirit, charcoal, production of mushroom, citric acid, gibberellic acid, antioxidant compounds, natural food colour, aroma compounds, biogas, phenol compounds etc. These compounds are the potential sources for the further utilization in the food industries and pharmaceutical industries. Regarding the value addition to the coffee waste one has to consider the economics of obtaining these by-products.


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References

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[27] Natarajan, C. P., Balakrishnan Nair, R., Gopalakrishna Rao, N., Viraktamath, C.S., Bhatia, D. S. and Sankaran, A. N. (1960). Studies on the roasting of coffee. Journal of Scientific and Industrial Research, 19 (A): pp. 32–37. [28] Shibamoto, T. (1991). An overview of coffee aroma and flavour chemistry. Fourteenth International Scientific Colloquium on Coffee, ASIC, San Francisco, pp. 107–110. [29] Abraham, K. O. and Shankaranarayana, M. L. (1987). Volatile flavour compounds in coffee. Indian Coffee, 51 (8): pp. 8–19. [30] Marcos, P. G. C., Ana, F. S. C., Clarissa, M. A., Flavia, R. B. G., Francisco, D. N., Gloria, M. B. A. (2003). Profile and levels of bioactive amines in green and roasted coffee, Food Chemistry, 82: pp. 397–402. [31] Vatinno, R., Aresta, A., Zambonin, C. G. and Palmisano, F. (2008). Determination of ochratoxin-A in green coffee beans by solidphase microextraction and liquid chromatography with fluorescence detection. Journal of Chromatography, 1187(12): pp. 145–150. [32] Zeller, B. L. and Kim, D. A. (2008). Gasified food products and methods of preparation thereof, US 0069924A1. [33] Raju, K. I. (1998). Coffee, adjuncts and adulterants. Indian Coffee, 62(4): pp. 7–10. [34] Ramalakshmi, K., Rao Prabhakara, P. G. and Abraham, K. O. (1994). Chemical analysis of chicory samples. Indian Coffee, 58(3): pp. 22– 24. [35] Sanchez-Gonaza, I., Jimenez-Escrig, F. and Saura-Calixto, F. (2005). In vitro antioxidant activity of coffees brewed using different procedures (Italian, espresso and filter). Food Chemistry, 90: pp. 133–139. [36] Galilea, L. I., Andueza, S., Leonarda, I., de Peña, M. P. and Cid, C. (2006). Influence of torrefacto roast on antioxidant and pro-oxidant activity of coffee. Food Chemistry, 94: pp. 75–80. [37] Cavin, C., Holzhaeuser, D., Scharf, G., Constable, A., Huber, W. W. and Schilter, B. (2002). Cafestol and kahweol, two coffee specific diterpenes with anticarcinogenic activity. Food and Chemical Toxicology, 40: pp. 1155–1163. [38] Schilter, B., Holzhaeuser, D. and Cavin, C. (2001). Health benefits of coffee. Proceedings of the 19th International Scientific Colloqium on Coffee. Trieste, pp. 14–18.


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[39] Higgins, L. G, Cavin, C., Itoh, K., Yamamoto, M., Hayes, J. D. (2007). Induction of cancer chemopreventive enzymes by coffee is mediated by transcription factor Nrf2. Toxicology and Applied Pharmacology, 226: pp. 328–337. [40] Smith, A. (2002). Effects of caffeine on human behaviour. Food Chemical Toxicology, 40: pp. 1243–1255. [41] Klatsky, A. L., Amstrong M. A., and Friedman, G. D. (1993). Coffee, tea and mortality. American Journal of Epidemiol, 3: pp. 375–381. [42] Mandel, H. G. (2002). Update on caffeine: consumption, disposition and action. Food Chemical Toxicology, 40: pp. 1231–1234. [43] Cook, D. G., Peacock, J. L., Feyerabend, C., Carey, I. M., Jarvis, M. J., Anderson, H. R. and Bland, J. M. (1996). Relation of caffeine intake and blood caffeine concentrations during pregnancy to foetal growth: prospective population based study. BMJ, 313: pp. 1358–1362. [44] Sakamoto, W., Nishihira, J., Fujie, K., Iizuka, T., Handa, H., Ozaki, M. and Yukawa, S. (2001). Effect of coffee consumption on bone metabolism. Bone, 28: pp. 332–336. [45] Sesso, H. D., Gaziano, J. M., Buring, J. E. and Hennekens, C. H. (1999). Coffee and tea and the risk of myocardial infarction. American Journal of Epidemiology, 149: pp. 162–167. [46] Atanas, G. A., Anna, A. D., Roberto, A. S., Schweizer, L. G., Nashev, E. M. and Maurer, A. D. (2006). Coffee inhibits the reactivation of glucocorticoids by 11b-hydroxysteroid dehydrogenase type 1: A glucocorticoid connection in the anti-diabetic action of coffee. FEBS Letters, 580: pp. 4081–4085. [47] Alan, H. V. and Jane, P. S. (1994). Coffee. Beverages, 2: pp. 191–236. [48] Petracco, M., (2001). Beverage preparation. In: Coffee Recent Developments, Clarke R. J. and Vitzthum, O. G. (eds.), pp. 140–162. [49] Urgert, R. (1997). Health effect of unfiltered coffee. Thesis, Agricultural University of Wageningen, The Netherlands. [50] Lione, A. A., Allen, P. V. and Crispin Smith, J. (1984). Aluminium coffee percolators as a source of dietary aluminium. Food and Chemical Toxicology, 22(4): pp. 265–268. [51] Basavaraj, K. (1997). Espresso coffee drinking. Indian Coffee, 61(7): pp. 3–5. [52] Piazza, L., Gigli, J. and Bulbarello, A. (2008). Interfacial rheology study of espresso coffee foam structure and properties. Journal of Food Engineering, 84: pp. 420–429.


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[53] Andueza, S., Vila, M. A., de Pena, M. P. and Cid, C. (2007). Influence of coffee/water ratio on the final quality of espresso coffee. Journal of the Science of Food and Agriculture, 87(4): pp. 586–592. [54] Yamada, M., Komatsu, S. and Shirasu, Y. (1997). Changes in components of canned coffee beverage stored at high temperature. In: Proceedings of the 17th ASIC Colloquium (Nairobi), pp. 250–210. [55] Gopalakrishna Rao, Natarajan, C. P. and Balachandran, A. (1970). Ready-mix coffee beverage. Indian Coffee, 34 (1): pp. 12–14. [56] Denker, M., Parat Wilhelms, M., Drichelt, G., Paucke, J., Luger, A., Borcherding, K., Hoffmann, W. and Steinhart, H. (2006). Investigation of the retronasal flavour release during the consumption of coffee with additions of milk constituents by oral breath sampling. Food Chemistry, 98: pp. 201–208. [57] Yamaguchi, T., Tsuchiya, H. and Kawauma, T. (2007). Coffee jelly beverage. JP 189922A. [58] Klug, S., Patrizio, F., Einstman, J., William, J. (1977). Iron-fortified soluble coffee and method for preparing same. US4006263. [59] Atkinson, J. R., Deis, D. A. and Marchio, A. L. (2001). Fortified coffee drink, U S 6207203B1. [60] Ros G. C. (2006). Procedure is for production of sweetened coffee, involves cleansing of impurities from gathered beans, selection by flotation and dry pulp extraction ES 2264375. [61] Kaku, K. and Chandler, K. P. (2004). Preparation of a coffee tablet. GB2394165A. [62] Barani, R. and Avanesions Z. S. (1997). A tablet for preparation of coffee drinks and a process for obtaining the tablet, EP 0813816A1. [63] Falkenstein, K. (1997). Coffee tablets with integrated roast aroma, US 2264375A1. [64] Kessler, U. (2004). Freeze dried coffee tablets. GB 2394163A. [65] Martinez G. G., Espinosa V. B., Valdez F. L. and Garcia U. A. (2003). Flavoured coffee. Alimentaria, 342: pp. 13–14. [66] Koda, M. and Takigawa, T. (2007). Flavoured coffee paste and method for producing the same, JP 289035A. [67] Tan, G. and Korel, F. (2007). Quality of Flavoured yogurt containing added coffee and sugar. Journal of Food Quality, 30(3): pp. 342–356.


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[68] Castaneda, R. R. (2003). Three fermented wines in same formula. Don Roberto’s sweet (yellow) mango wine, (dry) green mango wine and brewed coffee wine, WO 03/010279A1. [69] Winkelmann, M., Roebert, L., Arndt, T., Roesler, M., Moerl, L., Krueger, G. and Heinrich, S. (2000). Process for candying of coffee beans, DE 19902786 C1. [70] Ichikawa, H. (2008). Germinated coffee, WO 029578A1. [71] Gillenwater, R. E. and Gillenwater, L. A. (2008). Coffee filled packet, GE 2394164A. [72] Abreu A. R. M., Silva L. G., Silva F. A. and Motta, S. (2007). Development of cookie formulations containing coffee. Ciencia-eTecnologia-de-Alimentos, 27(1): pp. 162–169. [73] Peleg, Y. (1993). Microwave reconstitution of frozen pizza, US 5260070. [74] Ritchie, J. M. (1975). The xanthines. In: The Pharmacological Basis of Therapeutics. 5th ed., MacMillan, New York, pp. 367–368. [75] Europaisches, A. (1978). Degradation of caffeine by Pseudomonas alcaligenes CFR 1708 In: Coffeinum Theophyllinum, Deutscher Apotheker Verlag, Stuttgart, p. 670 and p. 1213. [76] Essig, D., Costill, D. L. and Van Handel, P. J. (1980). Effects of caffeine ingestion on utilization of muscle glycogen and lipid during leg ergometer cycling. International Journal of Sports Med, 1: pp. 86–90. [77] Spriet, L. L., MacLean, D. A., Dyck, D. J., Hultman, E., Cederblad, G. and Graham, T. E. (1992). Caffeine ingestion and muscle metabolism during prolonged exercise in humans. American Journal Physiology Endocrinology and Metabolism, 262: pp. 891–898. [78] Kalmar, J. M and Cafraelli, E. (1999). Effects of caffeine on neuromuscular function. Journal of Applied Physiology, 87: pp. 801–808. [79] Blecher, R. and Lingens, F. (1997). The metabolism of caffeine by a Pseudomonas putida strain. Hoppe-Seyler’s Z Physiol Chem, 358: pp. 807–817. [80] Srisuphan, W. and Bracken, M. B. (1986). Caffeine consumption during pregnancy and association with late spontaneous abortion. American Journal of Obstetrics Gynaecology, 155: pp. 14–20. [81] Mabbett, T. (2001). Common cause. Coffee and Cocoa-International, 28(6): pp. 27–28.


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[82] Farah, A., de Paulis, T.., Moreira, D. P., Trugo, L. C. and Martin, P. R. (2007). Chlorogenic acids and lactones in regular and waterdecaffeinated arabica coffees. Journal of Agricultural and Food Chemistry, 54(2): pp. 374–381. [83] Geyer, S. and Schulmeyr, J. (2007). Ecological and gentle technology – CO2 extraction and its use in food technology. Innovations-in-FoodTechnology, 34: pp. 44–46. [84] Sarath Babu, V. R., Patra, S., Thakur, M. S., Karanth N, G. and Varadaraj, M. C. (2005). Degradation of caffeine by Pseudomonas alcaligenes CFR 1708. Enzyme and Microbial Technology, 37: pp. 617–624. [85] Gokulakrishnan, S., Chandraraj, K., Sathyanarayana, N. and Gummadi. (2005). Microbial and enzymatic methods for the removal of caffeine. Enzyme and Microbial Technology, 37: pp. 225–232. [86] Sturdivant, S., (2001). Soluble coffee: Over a century of convenience. Tea and Coffee Trade Journal, 173 (4): pp. 25–29. [87] Bel-Rhlid, R., Kraehenbuehl, K., Lerch, K. and Aeschbach, R. (2006). Soluble coffee product, EP 1726213A1. [88] Silver, R.S. and Whalen P. E. (2007). Stabilized enzyme compositions, US 0237857A1. [89] Delgado, P. A., Vignoli, J. A., Siikaaho, M. and Franco, T. T. (2008). Sediments in coffee extracts: Composition and control by enzymatic hydrolysis. Food Chemistry, 110: pp. 168–176. [90] Boss, E. A., Rubens M. F. and Eduardo C. V. T. (2004). Freeze drying process: Real time model and optimization. Chemical Engineering and Processing, 43: pp. 1475–1485. [91] Zeller, B. L. and Kiessling, T. R. (2000). Foaming cappuccino

creamer containing gasified carbohydrate, US6129943, 10/10/2000.

[92] Nagabhushana, R. L. (1989). Speciality Indian golden mansooned coffee. Indian Coffee, 53(3): pp. 7–8. [93] Variyar, P. S., Rasheed A., Rajeev B., Zareena N. and Arun S. (2003). Flavouring components of raw monsooned arabica coffee and their changes during radiation processing. Journal of Agricultural and Food Chemistry, 51(27): pp. 7945–7950. [94] Rasheed A., Babitha T. and Bongirwar, D. R. (2003). Impact of gamma irradiation on the monsooning of coffee beans. Journal of Stored Products Research, 39(2): pp. 149–157.


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[95] Pandey, A., Soccol, C. R. and Larroche , C. (2008). Current Developments in Solid-state Fermentation, New York: Springer, pp. 356–376. [96] Borrelli, R. C., Fabrizio, E., Aurora, N., Alberto, R. and Vincenzo, F. (2004). Characterization of a new potential functional ingredient: Coffee silverskin. Journal of Agriculture and Food Chemistry, 52: pp. 1343–1338. [97] Bodmer, S. D. and Ruder, F. D. (2005). Coffee cherries’ spirit and its process of manufacture, EP 1593735A1. [98] Nakamura, T., Tokimoto, T., Tamura, T., Kawasaki, N. and Tanada, S. (2003). Decolorization of acidic dye by charcoal from coffee grounds. Journal of Health Science, 49(6): pp. 520–523. [99] Hernandez, D., Sanchez, J., Yamasaki, K. (2003). A simple procedure for preparing substrate for Pleurotus ostreatus cultivation. Bioresource Technology, 90: pp.145–150 [100] Fan, L., Pandey, A., Mohan, R. and Soccol, C. R. (2000). Use of various coffee industry residues for the cultivation of Pleurotus ostreatus in solid state fermentation. Acta-Biotechnologica, 20(1): pp. 41–52. [101] Shankaranand, V. S. and Lonsane, B. K., (1994). Coffee husk: An inexpensive substrate for production of citric acid by Aspergillus niger in a solid-state fermentation system. World Journal of Microbiology and Biotechnology, 10(2): pp. 165–168. [102] Machado, C. M. M., Oliveira, B. H., Pandey, A. and Soccol, C. R. (1999). Production of gibberllic acid from coffee byproduct. Proceedings of the Paper Presented at the 3rd International Seminar on Biotechnology in the Coffee Agro-industry, Londrina, Brazil, 39. [103] Yen, W., Wang, B., Chang L., and Duh, P. (2005). Antioxidant properties of coffee residues. Journal of Agriculture and Food Chemistry, 53: pp. 2658–2663. [104] Emille, R. B. A. and Leandro, S. (2007). Fresh coffee husks as potential sources of anthocyanins. LWT, 40: pp. 1555–1560. [105] Benoit, I., Navarro, D., Marnet, N., Rakotomanomana, N., Lesage, L., Sigoillot, J., and Aster, M. 2006. Feruloyl esterase as a tool for the release of phenolic compounds from agro-industrial by-products. Carbohydrate Research 341: pp. 1820–1827.


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5 Introduction to tea

5.1 Introduction Tea is continuing to expand in all of its forms – in grocery stores, convenience stores and on the favourite restaurant menu. Consumers are embracing Camellia sinensis for its health benefits as well as its delicious taste. In addition to increased availability of wide varieties of tea, improved brewing methods and equipments have changed the way people perceive tea [1].

5.2 Origin and history Teas have been cultivated for thousands of years in Asia. Based on the differences in morphology between Camellia sinensis (var. assamica) and Camellia sinensis (var. sinensis), botanists have long asserted a dual botanical origin for tea. Camellia sinensis (var. assamica) is native to the area from Yunnan province in China to the northern region of Myanmar and the state of Assam in India. Camellia sinensis (var. sinensis) is native to eastern and south-eastern China [2]. However, recent research questions this. The same chromosome number (2n=30) for the two varieties, easy hybridization, and various types of intermediate hybrids and spontaneous polyploids all appear to demonstrate a single place of origin for Camellia sinensis – the area including the northern part of Myanmar, Yunnan and Sichuan provinces of China [2]. Story of tea began in ancient China over 5,000 years ago (some time around 2737 BC). According to legend, the Shen Nong, an early emperor was a skilled ruler, creative scientist, and patron of the arts. His far-sighted edicts required among other things, that all drinking water be boiled as a hygienic precaution. One summer day while visiting a distant region of his realm, he and the court stopped to rest. In accordance to his ruling, the servants began to boil water for the court to drink. Dried leaves from the nearby bush fell into the boiling water, and a brown liquid was infused into the water [3]. The ever inquisitive

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and curious monarch took a sip of the brew and was pleasantly surprised by its flavour and its restorative properties. A variant of the legend tells that the emperor tested the medical properties of various herbs on him. Some were poisonous, but found tea to work as an antidote. Shen Nong is also mentioned in Lu Yu’s ‘Cha Jing’, a famous early work on the subject [4]. As a scientist, the emperor was interested in the new liquid, drank some and found it very refreshing. Therefore, according to the legend, tea was created. (This myth maintains such a practical narrative, that many mythologists believe it may relate closely to the actual events now lost in ancient history). According to a Tang dynasty legend which spread along with Buddhism, Bodhidharma and the founder of Zen school of Buddhism is based on a meditation known as “Chan”. After meditating in front of a wall for nine years, he accidentally fell asleep. He woke up in such disgust at his weakness that he cut off his eyelids and they fell to the ground and took root, growing into tea bushes. Sometimes, the second story is retold with Gautama Buddha in place of Bodhidharma. In another variant of the first mentioned myth, Gautama Buddha discovered tea when some leaves had fallen into boiling water. Whether or not these legends have any basis, tea has played a significant role in the Asian culture for centuries as a staple beverage, a curative, and as a symbol of status. It is not surprising that its discovery is ascribed to the religious or royal origins. Whether tea originated in India or China is still a matter of debate. One thing that is certain is that tea drinking was first initiated in China for medicinal purposes and later gained popularity as a nourishing beverage [4]. Tea cultivation flourished in India under the British and today India is the largest producer of tea in the world. After Europe adopted tea as its main hot beverage, China imposed restrictions on its export to the outside world The British established tea cultivation in the north-eastern parts of India. Organized cultivation spread to South India during the First World War years and later to Sri Lanka. Many features of tea cultivation and processing were standardized during this period and mechanization was undertaken to handle the ever-increasing crop to meet the global supplies. Green tea, which was normally made in China, was improved upon and Black tea manufacturing was set up which enhanced the shelf-life of tea and allowed it to be transported for longer duration to reach far flung areas. Darjeeling tea is grown in the foothills of the Himalayas and is a prized Indian black tea. This tea was marketed with vigorous campaigning by the royal family and it is still accepted among the best teas of the world [5]. Assam teas are known for their malty liquors and are promoted as the milk teas, and a


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newer process called CTC (Crush, tear and curl) was established to handle the huge bulk of the crop harvested during the rainy season. Indian teas came to be known world-wide as milk teas in many markets dominating over the lighter green teas coming out of China till then. The East India Company also had interests along the routes to India from Great Britain. The company cultivated the production of tea in India. Its products were the basis of the Boston Tea Party in Colonial America [5]. The Indian Tea Board took various programmes to protect the interests of the Indian tea industry. Genetic Inheritance (GI) registration process for establishing Darjeeling CTM (certification trade mark) was also initiated. In the 1600s, tea became popular throughout Europe and the American colonies. Since colonial days, tea has played a role in the American culture and customs. Today American school children learn about the famous Boston tea party protesting the British tea tax – one of the acts leading to the revolutionary war. During the 20th century, two major American contributions to the tea industry occurred. In 1904, iced tea was created at the World’s Fair in St. Louis, and in 1908, Thomas Sullivan of New York developed the concept of tea in a bag. Tea breaks down into three basic types: Black, Green, and Oolong. In U.S.A., over 90 percent of the tea consumed is black tea which has been fully oxidized or fermented and yields a hearty flavoured amber brew. Some of the popular black teas include English breakfast (good breakfast choice since its hearty flavour mixes well with milk), Darjeeling (a blend of Himalayan teas with a flowery bouquet suited for lunch) and Orange Pekoe (a blend of Ceylon teas that is the most widely used of the tea blends). Green tea skips the oxidizing step. It has a more delicate taste and is light green/golden in colour. Green tea, a staple in the Orient, is gaining popularity in the USA, due to recent scientific studies linking its consumption with reduced cancer risk. Oolong tea, popular in China, is partly oxidised and is a cross between black and green tea in colour and taste. While flavoured teas evolve from these three basic teas, herbal teas contain no true tea leaves. Herbal and medicinal teas are created from the flowers, berries, peels, seeds, leaves, and the roots of many different plants [3].

5.2.1 China Tea consumption spread throughout the Chinese culture, reaching into every aspect of the society. In 800 A.D., Lu Yu wrote the first definitive book on tea, the Cha Ching. This amazing man was orphaned as a child and raised by scholarly Buddhist monks in one of China’s finest monasteries. However, as a young man he rebelled against the discipline of priestly training which had made him a skilled observer. His fame as a performer increased with each year but he felt his life lacked meaning. Finally, in mid-life, he retired for 5


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years into seclusion. Drawing from his vast memory of observed events and places, he codified the various methods of tea cultivation and preparation in ancient China. The vast definitive nature of his work projected him into near sainthood within his own lifetime. Patronized by the emperor himself, his work clearly showed the Zen Buddhist philosophy to which he was exposed as a child. It was this form of tea service that Zen Buddhist missionaries would later introduce to imperial Japan [3].

5.2.2 Japan The returning Buddhist priest viz., Yeisei, who had seen the value of tea in China in enhancing religious meditation, brought the first tea seeds to Japan, and as a result he is known as the “Father of Tea” in Japan. Because of this early association, tea in Japan has always been associated with Zen Buddhism. Tea received almost instant imperial sponsorship and spread rapidly from the royal court and monasteries to the other sections of the Japanese society. Japanese tea ceremony – Tea was elevated to an art form resulting in the creation of the Japanese Tea Ceremony (“Cha-no-yu” or “the hot water for tea”). The best description of this – the Irish-Greek journalist-historian who probably wrote the complex art form ‘Lafcadio Hearn’, one of the few foreigners ever to be granted Japanese citizenship during this era. He wrote from personal observation, “The Tea ceremony requires years of training and practice to graduate in the art, yet the whole of this art, to its detail, signifies no more than the making and serving of a cup of tea. The supremely important matter is that the act be performed in the most perfect, polite, graceful and charming manner possible”. Such purity of a form of expression prompted the creation of supportive arts and services. A special form of architecture (chaseki) developed for “tea houses”, based on the duplication of the simplicity of a forest cottage. The cultural/artistic hostesses of Japan, the Geishi, began to specialize in the presentation of the tea ceremony. As more and more people became involved in the excitement surrounding the tea, the purity of the original Zen concept was lost. The tea ceremony became corrupted, boisterous, and highly embellished. “Tea Tournaments” were held among the wealthy where nobles competed among each other for rich prizes in naming various tea blends. Rewarding winners with gifts of silk, armour and jewellery was totally alien to the original Zen attitude of the ceremony. Three great Zen priests restored tea to its original place in Japanese society. Ikkyu (1394–1481), a prince who became a priest, was successful in guiding the nobles away from their corruption of the tea ceremony. Murata Shuko (1422–1502), the student of Ikkyu was very competent in re-introducing ‘The Tea ceremony’ into the Japanese society. Sen-no Rikkyu (1521–1591), a priest, set the rigid standards for the ceremony, which are intact even today


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and largely used. Rikkyu was successful in influencing the Shogun Toyotomi Hideyoshi, who became Japan’s greatest patron of the art of tea. A brilliant general, strategist, poet, artist and a unique leader facilitated the final and complete integration of tea into the pattern of Japanese life. There was complete acceptance to view tea as the ultimate gift, and warlords paused for tea before battles [3].

5.2.3 Europe While tea was at this high level of development in both Japan and China, information concerning this unknown beverage began to filter back to Europe. Earlier, caravan leaders had mentioned it but were unclear as to its service, format or appearance. One reference suggests that the leaves be boiled, salted, buttered and eaten. The first European to personally encounter tea and write about it was the Portuguese Jesuit Father Jasper de Cruz in 1560. Portugal, with her technologically advanced navy, had been successful in gaining the first right of trade with China. It was on the first commercial mission that Father de Cruz had tasted tea four years before. The Portuguese developed a trade route by which they shipped their tea to Lisbon, and then Dutch ships transported it to France, Holland, and the Baltic countries. At that time Holland was politically affiliated with Portugal. When this alliance was altered in 1602, Holland with her excellent navy, entered into full Pacific trade in her own right. When tea finally arrived in Europe, Elizabeth I had more years to live and Rembrandt was only six years old. Because of the success of the Dutch navy in the Pacific, tea became very fashionable in the Dutch capital – The Hague. This was due in part to the high cost of the tea (over $100 per pound) which immediately made it the domain of the wealthy. Slowly, as the amount of tea imported increased, the price fell as the volume of sale expanded. Initially available to the public in apothecaries along with such rare and new spices as ginger and sugar, it was available in common food shops throughout Holland by 1675. As the consumption of tea increased dramatically in the Dutch society, doctors and university authorities argued on the negative and/or positive benefits of tea known as “Tea Heretics”. The public largely ignored the scholarly debate and continued to enjoy their new beverage, though the controversy roughly lasted from 1635 to 1657. Throughout this period France and Holland led Europe in the use of tea. As the craze for oriental things swept Europe, tea became a part of the way of life. The social critic Marie de Rabutin-Chantal, the Marquise de Sevigne, makes the first mention in 1680 of adding milk to tea. During the same period, Dutch inns provided the first restaurant service of tea. Tavern owners would furnish guests with a portable tea set complete with a heating unit. The independent Dutchman would then prepare tea for himself and his friends outside in the tavern’s garden. Tea remained popular in France


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for only about fifty years, being replaced by a stronger preference for wine, chocolate and exotic coffees [3].

5.2.4 England Great Britain was the last of the three great sea-faring nations to break into the Chinese and East Indian trade routes. This was in part due to the unsteady ascension to the throne of the Stuarts and the Cromwell Ian civil war. The first samples of tea reached England between 1652 and 1654. Tea quickly proved popular enough to replace ‘Ale’ as the national drink of England whereas in Holland, it was the nobility that provided the necessary stamp of approval and so insured its acceptance. King Charles II married the Portuguese Infanta Catherine de Braganza during exile in 1662. Charles himself had grown up in the Dutch capital. As a result, both he and his Portuguese bride were confirmed tea drinkers. When the monarchy was re-established, the two rulers brought this foreign tea tradition to England with them. As early as 1600, Elizabeth I had founded the John Company for the purpose of promoting Asian trade. When Catherine de Braganza married Charles, she brought as part of her dowry the territories of Tangier and Bombay. Suddenly, the John Company had a base of operations. The John Company was granted the unbelievably wide monopoly of all the trade in east of the Cape of Good Hope and west of Cape Horn. Its powers were almost without limit and included among others the right to legally acquire territory and govern it; coin money, raise arms and build forts; form foreign alliances, declare war, conclude peace, pass laws; and try and punish lawbreakers. It was the single largest, most powerful, monopoly to ever exist in the world. In addition, its power was based on the import of tea. At the same time, the newer East India Company floundered against such competition. Appealing to Parliament for relief, the decision was made to merge the John Company and the East India Company (1773). Their re-drafted charts gave the new East India Company a complete and a total trade monopoly on all commerce in China and India. As a result, the price of tea was kept artificially high, leading to later global difficulties for the British crown. Tea mania swept across England as it had earlier spread throughout France and Holland. Tea imports rose from 40,000 pounds in 1699 to an annual average of 240,000 pounds by 1708 [3]. Prior to the introduction of tea into Britain, the English had two main meals, i.e. breakfast and dinner. Breakfast was Ale, bread, and beef. Dinner was a long, massive meal at the end of the day. It was no wonder that Anna, the Duchess of Bedford (1788–861), experienced a ‘sinking feeling’ in the late afternoon. Adopting the European tea service format, she invited friends to join her for an additional afternoon meal at five o’clock in her rooms at Belvoir Castle. The menu is centred on small cakes, bread and butter sandwiches,


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assorted sweets, and of course tea. This summer practice proved so popular that the Duchess continued it when she returned to London, sending cards to her friends asking them to join her for ‘Tea and walking in the fields’. London at that time still contained large open meadows within the city. A common pattern of service soon merged. The first pot of tea was made in the kitchen and carried to the lady of the house who waited with her invited guests, surrounded by fine porcelain from China. The hostess warmed the first pot from a second pot (usually silver) that was kept heated over a small flame. Food and tea was then passed among the guests with the main purpose of the visit being conversation [3]. Tea cuisine expanded quickly into a range of products such as wafer thin crustless sandwiches, toasted breads with jams, and regional British pastries such as scones (Scottish) and crumpets (English). At this time two distinct forms of tea services evolved, namely as high and low. ‘Low tea’ (served in the low part of the afternoon) was served in aristocratic homes of the wealthy and featured gourmet titbits rather than solid meals. The emphasis was on the presentation and conversation. ‘High tea’ or ‘Meat tea’ was the main or ‘High’ meal of the day. It was the major meal of the middle and the lower classes and consisted of mostly full dinner items such as roast beef, mashed potatoes, peas, and of course, tea [3]. Tea was the major beverage served in coffee houses, but they were so because coffee arrived in England some years before tea. These were called ‘penny universities’ exclusively for men because for a penny any man could obtain a pot of tea, a copy of the newspaper, and engage in conversation with the sharpest wits of the day. The various houses specialized in selected areas of interest—some serving attorneys, some authors and others the military. They were the forerunners of the ‘English Gentlemen’s Private Club’. One such beverage house was owned by Edward Lloyd and was favoured by ship owners, merchants, and marine insurers. That simple shop was the origin of the Lloyd’s, the worldwide insurance firm. It attempted to close the coffee houses which were made throughout the eighteenth century because of the free speeches encouraged, but such measures proved so unpopular and were always quickly revoked. Experiencing the Dutch tavern garden teas, the English developed the idea of tea gardens. Here ladies and gentlemen took their tea outdoors surrounded by entertainment such as orchestras, hidden arbours, flowered walks, bowling greens, concerts, gambling or fireworks at night. It was at such a tea garden that Lord Nelson, who defeated Napoleon by sea, met the great love of his life, Emma, known as Lady Hamilton later. Women were permitted to enter a mixed, public gathering for the first time without social criticism. British society (public) mixed here freely for the first time at these gardens, cutting across lines of class and birth [3].


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Tipping as a response to proper service developed in the tea gardens of England. Small locked wooden boxes were placed on the tables throughout the garden. Inscribed on each were the letters T.I.P.S, which stood for the sentence ‘To Insure Prompt Service’. If a guest wished the waiter to hurry (and so insure the tea arrived hot from the often-distant kitchen) he dropped a coin into the box on being seated ‘To Insure Prompt Service’. Hence, the custom of tipping servers was created.

5.2.5 Russia Imperial Russia was attempting to engage China and Japan in trade at the same time as the East Indian Company. The Russian interest in tea began as early as 1618 when the Chinese embassy in Moscow presented several chests of tea to the Czar Alexis. By 1689, the Trade Treaty of Newchinsk established a common border between Russia and China, allowing caravans to cross back and forth freely. Still, the journey was not easy. The trip was 11,000 miles long and took over sixteen months to complete. The average caravan consisted of 200– 300 camels. As a result of such factors, the cost of tea was initially prohibitive and available only to the wealthy. By the time Catherine the Great died (1796), the price had dropped to some extent, and tea was spreading throughout the Russian society. Tea was ideally suited to the Russian life – hearty, warm, and sustaining. The Samovar, adopted from the Tibetan hot pot, is a combination of bubbling hot water heater and teapot. Placed in the centre of a Russian home, it could run all day and serve up to forty cups of tea at a time. Again showing the Asian influence in the Russian culture, guests sipped their tea from glasses in silver holders, very similar to the Turkish coffee cups. The Russian have always favoured strong tea which is highly sweetened with sugar, honey, or jam. With the completion of the TransSiberian railroad in 1900, the overland caravans were abandoned. Although the revolution intervened in the flow of the Russian society, tea remained a staple throughout. Tea (along with vodka) is the national drink of the Russians today [3].

5.2.6 America By 1650, the Dutch were actively involved in trade throughout the Western world. Peter Stuyvesant brought the first tea to America and to the colonists in the Dutch settlement of New Amsterdam (later re-named New York by the English). Settlers here were confirmed tea drinkers. In addition, on acquiring the colony, the English found that the small settlement consumed more tea at that time than all of England put together [3].


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It was not until 1670 that English colonists in Boston became aware of tea, and it was not publicly available for sale until twenty years later. Tea Gardens were first opened in the New York City, already aware of tea as a former Dutch colony. The new gardens were centred on the natural springs, which the city fathers now equipped with pumps to facilitate the tea craze. The most famous of these were the tea springs at Roosevelt and Chatham (later Park Row Street). By 1720 tea was a generally accepted as a staple of trade between the colony and the mother country. It was especially a favourite of colonial women, a factor England was to base a major political decision on later. Tea trade was centred in Boston, New York, and Philadelphia, future centres of American rebellion. As tea was heavily taxed, even at this early date, contraband tea was smuggled into the colonies by the independent minded American merchants from ports far away, and adopted herbal teas from the Indians. The directors of the ‘then’ John Company (to merge with the East India Company later) fumed as they saw their profits diminish and so they pressured the Parliament to take action [3].

Tea and the American Revolution England had recently completed the French and the Indian war fought, from England’s point of view, to free the colony from French influence and stabilize trade. It was the feeling of Parliament that as a result, it was not unreasonable that the colonists shoulder the majority of the cost. After all the war had been fought for their benefit, Charles Townshend presented the first tax measures, which today are known by his name. They imposed a higher tax on newspapers (which they considered far too outspoken in America), tavern licenses (too much free speech there), legal documents, marriage licenses, and docking papers. The colonists rebelled against taxes imposed upon them without their consent and which were so repressive. New and heavier taxes were levelled by the Parliament for such rebellion. Among these was the tea tax in June 1767 that was to become the watershed of America’s desire for freedom. Townshend died three months later due to fever and he never knew that his tax measures helped create a free nation. The colonists rebelled and openly purchased imported tea, largely Dutch in origin. The John Company, already in deep financial trouble saw its profits fall even further. By 1773, the John Company merged with the East India Company for structural stability and pleaded with the Crown for assistance. The new Lord of the Treasury, Lord North, as a response to this pressure, granted to the new Company permission to sell directly to the colonists, bypassing the colonial merchants and pocketing the difference. In plotting this strategy, England was counting on the well-known passion among American women for tea to force consumption and it was a major miscalculation. Throughout


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the colonies, women pledged publicly at meeting and in newspapers not to drink English sold tea until their free rights, and those of their merchant husbands, were restored [3].

The Boston Tea Party By December 16, events had deteriorated enough that the men of Boston, dressed as Indians (remember the original justification for taxation had been the expense of the French and Indian war) threw hundreds of pounds of tea into the harbour. Such leading citizens as Samuel Adams and John Hancock took part. England had had enough. In retaliation, the port of Boston was closed and the city occupied by royal troops. The colonial leaders met and revolution declared. The trade continued in the Orient, though concerned over developments in America, English tea interests still centred on the product’s source—the Orient. There the trading of tea had become a way of life, developing its own language known as Pidgin English. Created solely to facilitate commerce, the language was composed of English, Portuguese, and Indian words all pronounced in Chinese. Indeed, the word pidgin is a corrupted form of the Chinese word for ‘does business’. So dominant was the tea culture within the English speaking cultures that many of these words came to hold a permanent place in our language. Mandarin (from the Portuguese ‘mandar’ meaning ‘to order’) – the court official empowered by the emperor to trade tea. Cash (from the Portuguese ‘caixa’ meaning ‘case or money box’) – the currency of tea transactions; Caddy (from the Chinese word ‘one pound weight’) – the standard tea trade container; Chow (from the Indian word ‘food cargo’) – slang for food.

The Opium Wars Not only was language a problem, but also was the currency. Vast sums of money were spent on tea. Transportation of large amounts of currency out of England would have been impossible to transport safely half way around the world and the country would have collapsed financially. With plantations in newly occupied India, the John Company saw a solution. In India, they could grow the inexpensive crop of opium and use it as a means of exchange. Because of its addictive nature, the demand for the drug would be long, insuring an unending market. Chinese emperors tried to maintain the forced distance between the Chinese people and the devils. However, disorder in the Chinese culture and foreign military might have prevented it. The Opium Wars broke out with the English ready to go to war for free trade (their right to sell opium). By 1842 England had gained enough military advantages to enable her to sell opium in China undisturbed until 1908 [3].


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America began direct trade with China soon after the revolution was over in 1789. America’s newer, faster, clipper ships out-sailed the slower, heavier English tea wagons that had dominated the trade until then. This forced the English navy to update their fleet, a fact America would have to address in the War of 1812. The new American ships established sailing records that still stand for speed and distance. John Jacob Astor began his tea trading in 1800. He required a minimum profit of 50% on each venture and often made 100%. Stephen Girard of Philadelphia was known as the gentle tea merchant. His critical loans to the young and weak American government enabled the nation to re-arm for the war of 1812. The orphanage founded by him still perpetuates his good name. Thomas Perkins was from one of Boston’s oldest sailing families. The trust of the Chinese in him as a gentleman of his word enabled him to conduct enormous transactions half way around the world without a single written contract. His word and his handshake was enough – so great was his honour in the eyes of the Chinese. It is to their everlasting credit that none of these men ever paid for tea with opium. America was able to break the English tea monopoly because its ships were faster and it paid in gold. By the mid-1800 the world was involved in a global clipper race as nations competed with each other to claim the fastest ships. England and America were the leading rivals. Each year the tall ships would race from China to the tea exchange in London to bring in the first tea for auction. Though beginning half way around the world, the mastery of the crews was such that the great ships often raced up the Thames separated by only by minutes. However, by 1871 the newer steamships began to replace these great ships [3].

5.2.7 Global tea plantations The Scottish botanist Robert Fortune, who spoke fluent Chinese, was able to sneak into mainland China the first year after the opium war. He obtained some of the closely guarded tea seeds and made notes on tea cultivation. With the support from the Crown, various experiments in growing tea in India were attempted. Many of these failed due to bad soil selection and incorrect planting techniques. However, through each failure, the technology was perfected. Finally, after years of trial and error, fortunes made and lost the English tea plantations in India and other parts of Asia flourished. The great English tea marketing companies were founded and production mechanized as the world industrialized in the late 1880s.

5.2.8 Iced tea and teabags America stabilized her government, strengthened her economy, and expanded her borders and interests. By 1904, the United States was ready for the world


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to see her development at the St. Louis world’s fair. Trade exhibitors from around the world brought their products to America’s first world’s fair. One such merchant Richard Blechynden, a tea plantation owner, had planned to give away free samples of hot tea to fair visitors. However, when a heat wave hit no one was interested. To save his investment of time and travel, he dumped a load of ice into the brewed tea and served the first iced tea. It was the hit of the fair. Four years later, Thomas Sullivan of New York developed the concept of bagged tea. As a tea merchant, he carefully wrapped each sample delivered to restaurants for their consideration. He recognized a natural marketing opportunity when he realized the restaurants were brewing the samples in the bags to avoid the mess of tea leaves in the kitchens.

5.2.9 Tea rooms, tea courts and tea dances Beginning in the late 1880s in both America and England, fine hotels began to offer tea service in tea rooms and tea courts. In the late afternoon, Victorian ladies (and their gentlemen friends) could meet for tea and conversation. Many of these tea services became the hallmark of the elegance of the hotel, such as the tea services at the Ritz (Boston) and the Plaza (New York). By 1910, hotels began to host afternoon tea dances. These swept the United States and England [3].

5.2.10 Vari (Tea) – English breakfast The prototype of this most popular of all teas was developed over a hundred years ago by the Scottish tea master Drysdale in Edinburgh. It was marketed simply as breakfast tea. It became popular in England, as Queen Victoria created the craze for Scottish (the summer home of Victoria) things. Teashops in London, however, changed the name and marketed it as English breakfast tea. It is a blend of fine black teas, often including some Keemun tea. Many tea authorities suggest that the Keemun tea blended with milk creates a bouquet that reminds people of toast hot from the oven and maybe the original source for the name. It should be offered with milk or lemon. (One never serves lemon to a guest if they request milk as it would curdle the milk.) It may also be used to brew iced tea.

5.2.11 Irish breakfast The Irish have always been great tea drinkers, and they drink their tea brewed very strong. In fact, there is a common tea saying among the Irish is that “a proper cup of tea should be strong enough for a mouse to trot on”. Along the same line, the Irish believed there were only three types of tea fit to drink. The first and best of quality was in China. The second best was sent directly


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to Ireland. The third and lowest in quality was sent to the English. Irish tea is usually drunk only in the morning because of its robust flavour, except for the Irish who drink it all day. Usually it is blended with an Assam tea base. Due to its taste, it is served with lots of sugar and milk.

5.2.12 Tea – Commercial varieties Caravan, this excellent tea was created in imperial Russia from the teas brought overland by camel from Asia. Because the trade route was dangerous and supplies unsteady, Russian tea merchants blended the varying incoming tea cargoes, selling a blend rather than a single tea form. It was usually a combination of black teas from China and India. Like the Irish, the Russian favoured this tea all day long. Earl Grey (1764–1845), though he was prime minister of England under William IV, is better remembered for the tea named after him. Tea legends say a Chinese mandarin gave the blend to him seeking to influence trade relations. A smoky tea with a hint of sweetness to it and served plain is the second most popular tea in the world today. It is generally a blend of black teas and bergamot oil. Black teas and Oolong Darjeeling refers to the tea grown in the mountain area of India. The mountain altitude and gentle misty rains of the region produce a unique full-bodied but a light flavoured, with a subtly lingering, aroma reminiscent of muscatel and highest grade. Reserved for afternoon use, it is traditionally offered to guests with lemon and without milk. Oolong, the elegant tea is sometimes known as the champagne of teas. Originally grown in the Fukien province of China, it was first imported to England in 1869 by John Dodd. Today, the highest grade Oolongs (Formosa Oolongs) are grown in Taiwan. A cross between green and black teas, it is fermented to achieve a delicious fruity taste. It is perfect for afternoon use with cucumber sandwiches and madeleine. Green tea makes up only ten percent of the world’s produced tea. The Japanese tea service (in which green tea is used) is an art. The serving of a full Japanese tea service would be beyond the ability of most properties and as a result, should not be attempted. Green tea is generally not a part of the afternoon tea tradition as appropriate to the hotel use. Keemun China Teas is the most famous of China’s black teas. Because of its subtle and complex nature, it is considered the burgundy of teas. It is a mellow tea that will stand alone as well as support sugar and /or milk, because of its wine-like quality [3] Today the bush tea is known as Camellia sinensis (L.) O. Kuntze of which there are two varieties: var. sinensis and var. assamica. In 1690, Kaempfer, a German medical doctor cum botanist who came to Japan from Holland and


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observed the habit of tea drinking among the people, named the bush Thea. In 1753, the famed botanist Linne gave the name of Camellia sinensis, changing its original naming of Thea sinensis. Since, the nomenclature of tea bush has been confused between these two names, in 1958 a British botanist Sealy classified all plants in Genus Camellia and tea was given the name it has today [6]. Tea is cultivated successfully in many different countries of the world and consumed in almost every part of the world, but the association of tea with China remains strong. Today the birthplace of tea is assumed to be southwestern China, centred in Yunnan district [7]. There are two approaches in tracing the history of tea usage, viz., anthropological or archival. Chinese legend claimed that the tea consumption goes back as far as 2737 BC. The first credible documentary reference on tea was made in 59 BC in a servant’s contract which stated that his duties included the making of tea and going to the city to buy it. Lu Yu, who described the botany, cultivation and processing of tea, as well as the utensils and proper way of drinking tea, etc., in his writings in detail, Tea classics or tea sutra has been the bible for people involved with tea ever since [8].

5.3 Tea production 5.3.1 World scenario of production and trade

Figure 5.1 Major tea producing countries [9]


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China and India are the two largest producers as well as consumers of tea. In global production, China’s contribution is 31% while that of India is 25% (Figure 5.1). The contribution of both in global tea business is 18% and 11% respectively. Other countries like Kenya, Sri Lanka, Vietnam and Indonesia contribute 25% of the world tea and control 50% of the world trade [9]. Food and Agriculture Organization (FAO) reports that the market for tea industry is expected to grow at 3% per annum. With the removal of quantitative restrictions (QRs) following World Trade Organization (WTO) regulations coming into force, the consumption is going to increase in developing countries. During the last four decades, Kenya has increased tea production by 25 times. Chinese tea production has witnessed a cumulative growth rate of 4.6%. The production growth rates have been slower in India and Sri Lanka at 2.3% and 0.9% respectively, during the same period. The area under cultivation has gone up by 33% in India and ten times in Kenya during the last 40 years [10].

5.3.2 Indian scenario Indian is one of the largest producer and consumer of tea in the world. In India, tea is grown in 15 states. Among these states, the major share is by Assam (50%), followed by West Bengal (24%), Tamil Nadu (17%) and Kerala (7%), others account for remaining 2%. India accounts for 20% of the total area under tea cultivation in the world, 25% of global tea production, 22% of world tea consumption and 11% of total tea exports [9]. India also leads in global research and development in tea industry. India is the largest manufacturer and exporter of tea machinery. The annual per capita consumption in India is low at 800 g compared to other countries like Pakistan (950 g), Sri Lanka (1.2 kg), UK (2.3 kg) and Bangladesh (1.2 kg). The annual tea production has been above 900 million kg for the last four years (Table 5.1). The tea production grew at an average annual rate of 2.3% during last 4 decades and 1.4% in the last decade. But over last few years the consumption growth has slowed down, this coupled with falling exports (Table 5.2) has led to surplus supply, and so the prices are declining in the market. It has reflected in the statistics of auction centres [10]. Table 5.1 Production of tea in India from 2001 to 2008 (in million kg) [11]

State

Assam West Bengal Tamil Nadu


2001

2002

2003

2004

2005

2006

2007

2008

132

143

167

163

159

164

161

171

454 187

433 188

435 201

436 215

487 218

502 237

512 236

487 233

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Kerala India*

65 854

58 838

58 878

62 893

63 946

59 982

560 987

70 981

*Includes other states also Table 5.2 Tea exports from India during 2006–2008 [12]

Year Quantity (in million kg) Value (in crores) Unit price (Rs/kg)

2006 218.73

2007 178.75

2008 203.12

2006.53 91.73

1810.11 101.26

2392.91 117.81

5.4 Botanical and taxonomical characteristics Tea as a commercial crop includes several species within the Genus Camellia in the family Theaceae. The Genus Camellia includes 82

species, which are mostly indigenous to the highlands of South-East Asia [6]. The systematic position of the tea plant is given in Table 5.3. Table 5.3 Systematic taxonomical position of tea

Division

Angiospermae

Class

Dicotyledones

Order

Parietales

Family

Theaceae

Genus

Camellia

Species

sinensis

Tea is commonly accepted as Camellia sinensis (L) O. Kuntze, irrespective of any variation in the characteristics. This is normally a diploid (2n=30 chromosomes) but polyploids occur. Taxonomically, four basic varieties of the tea plant are recognized commercially – China type (Camellia sinensis var. sinensis), Assam type (Camellia sinensis var. assamica), Cambodia type (Camellia sinensis var. lasiocalyx), and the hybrid of China and Assam types [13]. Based on leaf pose and growth habitat, two intra specific forms of C. sinensis (L.) are China variety, Camellia sinensis var. sinensis (L.) and Assam variety, Camellia sinensis var. assamica (Kitamura). The characteristic features that separate these two varieties are presented in Table 5.4 [6, 14]. Table 5.4 Characteristics of two tea varieties

Variety


Sub-variety

Growth habitat

Leaf features

Leaf pose

Leaf angle

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China Camellia sinensis var. sinensis (L.)

Camellia sinensis var. sinensis f. paviflora (Miq) Sealy Camellia sinensis var. sinensis f. macrophylla Sieb (Kitamura)

Assam Camellia sinensis var. assamica (Kitamura)

_

Dwarf, slow growing, shrub like

Small, erect narrow, dark green

Erectophile

70 degree

5.4.1 General characteristics Tea plant is an evergreen perennial shrub most often reaching a height of 30 ft. The leaves are of small length 5.5–6.1 cm, by width 2.2–2.4 cm, alternate, evergreen, elliptical, acuminate, serrated margins, glabrous sheet with pubescent below surface and become dark green and leathery on maturity. The flower buds originate either singly or in clusters from the side buds, flowers are white with 5 to 7 leathery sepals and petals. Fruits are glabrous, brownish green in colour, and trilobate with 1–3 seeds.

5.5 Cultivation practices 5.5.1 Climatic requirements The temperature in the range of 18–30°C is optimal for shoot growth. The minimum air temperature for shoot growth appears to be 13–14°C. Soil temperature is also important and optimum growth occurs between 20°C and 25°C [15].

5.5.2 Soil type Tea is grown in a wide variety of soil types, ranging from alluvial soils, drained soils and peat in the soil derived from volcanic ash. Growth of tea is favoured by acidic conditions, a pH value of 5.0–5.6 being considered optimum. Tea will not grow in soils with a pH value as low as 4.0 but soils with a pH value


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only marginally above 5.6 are considered unsuitable. Soils with pH values above 6.5 are not amenable to treatment and cannot be used for tea cultivation [15].

5.5.3 Land preparation Land clearance is required for tea cultivation as per the rules of different countries. The accumulation of large quantities of decaying vegetation can lead to significant rise in pH values and cleared material should be removed from the site. Burning is not recommended, as ash will also raise the soil’s pH value. Soil should be mixed well and proper drainage should be provided [15].

5.5.4 Seed Tea propagation is done by sowing seeds directly into the field and also by vegetative propagated clones. The quality of seeds within a single batch can vary considerably and a simple grading by floatation is applied immediately before planting. Seeds that remain floating after 72 h are unsuitable for use. Seeds require cracking before use to permit water entry and ensure a high and even rate of germination. Nursery beds require good quality of top soil. Shade is necessary for young plants, the shade density being progressively reduced until the plant is exposed to full sunlight and fertilizer is generally applied as foliar spray. In the field, bushes should be planted as closely as possible, to give complete ground coverage without over-crowding. Optimum spacing is dictated by the branching patterns of clones. Tea plants are most commonly planted as hedges, plant with the hedges are usually planted 0.6–0.8 m apart, with a space of about 1.2 m between the hedges [15].

5.5.5 Hoeing Hoeing is an operation in which soil around young plants is frequently loosened to a depth of 3 inches for a distance of 12 inches around. The hoeing helps to cut down the weeds and also helps in better aeration [8].

5.5.6 Irrigation Irrigation is an absolute necessity in countries such as Zimbabwe, where annual rainfall may be less than 700 mm. Irrigation should be considered where regular dry seasons of three to six months may be expected, where potential soil water deficits 300 mm annually. Evaporative loss of water in a whole year from many tea areas exceeds 1270 mm, which is believed to be a minimum annual requirement of water by tea plant [16].


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5.5.7 Fertilizer requirements The requirements of major nutrients like nitrogen, phosphorus and potassium for the tea plant are as follows, nitrogen at the rate of 200–300 kg, phosphorus ranges from 75 to 100 kg and potassium application ranges from 100 to150 kg per hectare [16].

5.5.8 Shade trees and windbreaks The role of shade trees and shelter in tea husbandry has been the subject of discussion for many years. The finding that yields were often higher without shade led to the removal of shade trees. Shade trees were, however, valuable in some low altitude tree growing areas, particularly Assam, due to the maintenance of the air temperature with in the optimum range. Leaf fall from shade trees can also improve the nutrient status and physical conditions of soil. Trees grown under shade will be blacker due to more chlorophyll but has lower polyphenol content, more of amino acids and caffeine content. The major types of tree grown for shade in tea plantations include: Albizzia stipulate, A. procera; Dalbergia assamica and Derris Robusta in north India, and Eryrhrina lithosperma, Dalbergia sisso, Albizzia lebbeck and Grevillea Robusta in south India. High winds have an adverse effect on tree through physical damage, reduction of leaf temperature and increased transpiration rate. Belts of shelter can transfer these effects. The shelter trees can reduce yield through competition for nutrients and water and through shading. Belts of shelter trees are usually justified only where very high wind is common. Apart from all these, mulching and top dressing are done at regular intervals.

5.5.9 Pest and diseases Major pests of tea includes tea mosquito bug (Helopeltis theavora), red spider mite, pink mite, green fly, thrips, aphides, crickets, tea mealy bugs, Leafy feeding caterpillar (Homona coffearia), etc. Major diseases of leaves, shoot and root are mentioned in Table 5.5. Table 5.5 Diseases of tea plant

Plant part Leaves


Disease

Blister blight Grey blight Brown blight Anthacnose Eye spot Brown spot

Causative organism

Exobasidium vexans Pestalotia theae Colletotrichum camilleae Colletotrichum thea-sinensis Pseudocercospora ocellata Calonectria spp.

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Bacterial blight Stem canker Armillaria rot Charcoal rot Red rot Brown root Violet root

Pseudomonas syringe pv. theae Phomopsis theae Armillaria mellea Ustulina deusta Poria hypolateritia Fomes noxius Sphaerostillbe repens

5.5.10 Harvesting The harvesting is done manually by employing labourers. This is expensive compared to mechanical harvesting. Irrespective whether manual and/ or mechanical plucking is used, it is usual to maintain a flat plucking table parallel to ground. Manual labourers are able to maintain the correct level by the use of a light pole, while wheeled harvesting equipment maintains a preset level. Maintaining a flat plucking table is, however, difficult where held mechanical sheers hand is used. It is important to stress that freshly harvested tea shoots are perishable. These can be bruised or broken easily, there by premature triggering the fermentation process and causing deterioration in quality. To avoid these problems, it is necessary to begin the manufacture process as quickly as possible after harvest. The most popular factor is coarseness of harvest (leaf number per shoot). The polyphenol and caffeine content is highest on dry weight basis in the youngest leaf of a given shoot. The content drops with each older leaf moving down the stem. It is very important that the harvested shoots are uniform. Without uniformity at the front end, it is very difficult to manage all the later steps. In north India the method of plucking involves two leaves and a bud (Figure 5.2). In south India however tea is plucked year round and the practice is to pluck two leaves and a bud, leaving the fully developed leaves on the bush exclusive of sheath leaf, which is called as Jannum or fish leaf. From the second flush until the end of July one fully matured leaf is left beside the fish leaf. From the first of August, close plucking is practiced. The interval between each pluck is 7–9 days. Plucking may be coarse or fine. Fine plucking involves plucking two leaves and a bud. Coarse plucking involves plucking 3 or 4 leaves [15].

5.5.11 Pruning Pruning is a necessary evil for tea plants. Shaping of new bushes is to develop new surface with new shoots and it is achieved by pruning and bending branches down and pegging into position, is commonly referred as bringing into bearing. After the bush is brought into bearing but before regular plucking has commenced, a procedure commonly known as tipping is applied. This is


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intended to level the plucking surface and to increase the number of plucking points. Pruning is required to remove all stems above the basic frame of the bush [16]. The frequency of pruning i.e., the pruning cycle, varies from 1 to 4 years. For economic reasons, it is desirable to prune during the dry seasons when yield is low. Usually, pruning is done at a height of 8 to 15 inches from ground level. A very light pruning is sometimes possible as an alternative to full maintenance pruning. Only the over crowded upper layer is removed and bushes are out of production for only a short period. On the other hand, light pruning cannot maintain a bush in a satisfactory condition indefinitely, so it is necessary to prune very heavily below the lowest normal prune. This is variously referred as collar pruning. Heavy pruning is done once in ten years. Pruning helps to get good growth in subsequent season [16].

Figure 5.2 Tea garden; two leaves and a bud

5.5.12 Adulterants Most common adulterants are the leaves of other plants. Commonly used leaves are beech (Fagus sylvatica), hawthorn (Crataegus oxycantha), sloe (Prunus spinosa), oak, poplar, maple and other trees. Another formerly wide spread adulteration was the addition of spent tea leaves. These spent teas were impregnated with catechins, caramel, campeachy wood, indigo, berlin blue, curcuma, humus, graphite etc. Adulteration can be detected by microscopic examinations and can often be discovered by chemical means, particularly by the estimation of hot water extract, tannin and total water-soluble ash [8].


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6 Types of tea and processing

6.1 Introduction Processed tea can be classified on the basis of established quality and processing methods. There are six types of processed teas – green, green brick, yellow, white, oolong and black tea. This categorization is based on the degree of fermentation and oxidation of simple polyphenols present in tea leaves. Green and yellow teas are unfermented. Polyphenols are hardly oxidized in green tea, but these are subjected to non-enzymatic oxidation in yellow tea. White, oolong (red) and black teas are fermented with white having least fermentation and black having the most. All these have distinct flavours and qualities that are determined by the degree of oxidation of polyphenols, whether enzymatic or non-enzymatic [17].

6.2 Green tea Green tea (Figure 6.1) is widely preferred in Japan and China and is produced from var. sinensis. With respect to demand in the world market, green tea is next to black tea. There are two types of green tea manufacturing process – Japanese method (Sen-cha process) and Chinese method (Pan-fried green tea).

6.2.1 Sen-cha process Sen-cha was developed in the 18th century in the Uji area – the prosperous area traditionally associated with producing the ceremony tea. Before Sen-cha was developed, a primitive tea was made by sun drying after steaming or parching the leaves. The process (Figure 6.2) consists of a series of controlled heating and curing operations. Plucked leaves are steamed for 45–60 s, then cured and dried in hot air at 90–110°C for 40–50 min. This primary drying and rolling process reduces the moisture from 76% to about 50%. The leaves are further rolled for 15 min without heat and then pressed and dried for 30–40 min in hot air at 50–60°C. This secondary drying reduces the moisture content of the

87


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tea to about 30%. A further curing is followed by third drying stage, in which the tea leaves are dried directly on a hot pan at 80–90°C and twisted for 40 min under pressing and rolling by a curing-hand mounted on the pan. Finally, the tea leaves are dried at 80°C, until moisture content of 6% is achieved. And then a fine needle-like form of Sen-cha tea is prepared [15].

Figure 6.1 Green tea

Plucking

Transportation

Steaming (Sen-cha)

Pan-fried (Kamairi-cha)

Drying and machine rolling

Final drying

Packaging Figure 6.2 Manufacture of green tea


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6.2.2 Pan-fried process (Kamairi-cha) Pan-fried tea had become popular in China by the 14th century or during the Ming Dynasty era. Kamairi-cha production differs from Sen-cha production by omitting the steaming operation and by using a higher temperature in the first firing stage (Figure 6.2). The manufacturing process for pan-fried tea is as follows: Fresh leaves are fried in a pan at 250–300°C for 10–15 min with agitation, 4–5 times per minute, to protect the leaves from burning. During frying, the greenish odour note is evaporated and the typical pan-fried aroma is developed. The leaves are manipulated to one of the three shapes characteristic of Chinese green tea during 10–15 min in a roller, and then dried at 100–150°C in a pan. The products are the gun type of tea which is ball-like – the chun-mee and sow-mee types which have a fine, twisted form, and the pan-fired type which has a flat form and has been polished to a pale white colour [15].

6.3 Green brick tea Green brick tea is an excellent beverage having a high demand in Mongolia, China and Central Asian Republics of the U.S.S.R. The manufacture of green brick tea differs from that of other teas in both raw materials and the processing procedures. In contrast to other teas, green brick tea is not only a flavoured product but also consumed as a soup prepared from water or milk supplemented with butter, mutton fat and salt. Green brick tea is produced from the coarse tea leaves and wastes obtained from autumn and spring pruning of tea plantations. Green brick tea production technology includes two independent steps:

(a) Preparation of half-finished lao-cha (b) Pressing into green brick tea

In Chinese lao-cha means old tea. Lao-cha is produced from November to February / March from raw material of two kinds – one for coating and other for inner portion of brick tea. The raw materials used for making the coating portion should be of higher quality than that used to obtain the inner portion. The inner material is made mainly of coarse shoots having up to 12 leaves on green stalk and may also include green and brown stalks. In general, green brick tea contains 70% leaves and 30% lignified stalk. There are two methods of lao-cha production technology. An ancient Chinese method dates back to old times and other method developed at Bakh Institute of Biochemistry, U.S.S.R. Academy of Sciences [18].


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The Chinese method requires many technological operations to be carried out for 16–20 days. The first step is raw tea roasting. The roasted tea is allowed to stand for 2–3 h in small stacks and then is cooled, rolled and dried to reduce moisture to 18–20%. The dried lao-cha is kept in large stacks to assure the basic fermentation. The time when the temperature reaches 55–65°C, is regarded as the end of fermentation process. To achieve uniform fermentation throughout the entire tea bulk, the inner portion is removed and changed to the outside. After 5 days, the temperature of inner portion of the stalk rises again to 50°C. This indicates termination of fermentation process. The stalk is then taken apart, loosened, cooled and exposed to final frying. Later the tea is fried at 85–90°C to reduce moisture content 8–9%. This is the end of lao-cha process. The lao-cha fermentation process takes 20 days. The Chinese method has no scientific support. As indicated above, the fermentation that induces selfwarming and formation of the quality was supposed to be a microbiological process. In an alternate method, roasting, at high temperature, rolling and thermal treatments are performed in specially designed boxes, and firing in regular tea firing furnaces. This technological scheme is used for the production of lao-cha [18]. Pressing 400 g of the coating material and 1600 g of the inner material are exposed to steaming and pressing. As a result, tea bricks of 2000g are produced. Half of the coating material is used to cover the lower layer and the other half for the upper layer. The first stage in green brick production is laocha steaming. Each portion of the coating and inner material is wrapped up in a cloth napkin and exposed to water vapour at 6–7 atm for 2 min at 95–100°C. As a result, the lao-cha bulk loosens and can be readily pressed. The lao-cha bulk thus prepared is placed into a machine in a certain order. At first half, 200g of coating material, then the inner material 1600 g and finally remaining half (200 g) of the coating material are placed. Then the press machine filled with well-arranged lao-cha is moved onto the hydraulic press that presses brick tea at a pressure of 100–110 atm. The press machine is transferred onto the conveyor line where it moves slowly. Tea bricks are allowed to stand in the press machine for 60min in order to retain a standard shape, strength and to cool down. Additional drying is needed because in steaming the moisture content of lao-cha increases. The drying is carried out in the drying chamber at 34–36°C with a relative humidity of 50–55%. The drying process is applied for 15–20 days to reduce the moisture content to 11% at the most. Finally, the green brick tea is wrapped up into paper and sixteen bricks are packed in each standard plywood box. The bricks are of following size – 350 mm long, 160 mm wide and 31–33 mm thick [19]. The investigation at Bakh Institute of Biochemistry, U.S.S.R. Academy of Sciences, disproved the theory. The self-warming of lao-cha in stacks was


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found to be a physico-chemical process, and developing under the influence of increased temperature and humidity. Exposure of the sterile raw tea to 55– 65°C produced lao-cha of high quality. Eventually, an alternate method of lao-cha production was developed; the method shortened the technological procedures from 20 days to 10–20 h, and increased markedly the manufactured tea quality. This method involves three steps in the lao-cha manufacture – (i) roasting and high temperature rolling; (ii) thermal treatment; (iii) firing.

6.4 Yellow tea Yellow tea (Figure 6.3) occupies intermediate position between the black and green teas, and is close to green teas [18]. The yellow tea infusion is of a bright colour than that of green tea. Yellow tea is pleasant refreshing beverage. It has a milder taste and strong aroma than green tea. Yellow tea is extremely popular in China and few other countries. In China, it is called blue tea occasionally, because the boiled tea leaf is dark blue and the dry tea has a bluish shade. Yellow tea produced from second and third leaves and tender shoots of tea plant [20]. A description of the yellow tea production technology is described in the following steps:

6.4.1 Withering Withering is the first step in the yellow tea production. It is important to apply uniform withering to the tender part of the shoot and the bud. The first leaf should not be withered to the same extent as that of the third leaf and the stalk. The withering is performed to reduce the moisture to 62–64%.

6.4.2 Roasting and rolling Following withering, the tea material is roasted in boilers at 166–176°C for 2–3 min with continuous stirring. The withered and roasted tea leaves are allowed to cool down for 30–60 min. At this stage, the leaf looses its grassy odour and acquires pleasant aroma. The leaf is exposed to high temperature rolling for 50–60 min.

6.4.3 Firing The first step is performed at 90–95°C to assure moisture content of 5–7% and subsequent thermal treatment decreases the moisture content to 4–5%. In the course of yellow tea manufacturing, tannins, volatile compounds and other constituents undergo chemical transformations. For instance, the content of tannin decreases by 1.2% and that of volatile aldehyde increases from 1.46 to


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7.01 mg per 100 g dry tea. These changes develop primarily at the stages of withering, roasting and rolling [21]. Yellow tea manufacture does not include fermentation. Nevertheless, in withering, roasting, rolling and frying, a portion of tannin undergoes oxidation and therefore, dry yellow tea is darker than green tea. Its infusion looks like that of green tea but has an organic shade. The taste of yellow tea differs from that of green tea. The aroma of yellow tea is stronger and superior than that of green tea. During 1970s, yellow tea production was initiated in Georgia [19]. The content of extractives of tea in the Georgian yellow tea is 48.4% and in Chinese 46.3%. The total amount of tannin is 21.5% and 24.5% whereas the content of catechins is 16.0% and 19.8%, in Georgian and Chinese teas respectively. The chromatographic separation of tannin from the Georgian and Chinese yellow tea has demonstrated that the qualitative composition of catechin is identical [18].

Figure 6.3 Yellow tea

6.5 White tea White tea is produced in the Fujian province and accounts for less than 0.1% of the total tea production. It is a fermented tea peculiar to China and originated before the 16th century. Raw material consists of fresh leaves from the first plucking of spring tea with a moderate content of polyphenol. These are large and medium leaves with profuse hair. Sprouting buds are used for the processing of the bud white tea group while the sprouting bud with two to three fresh leaves for other white tea groups. Brief description of the manufacturing process is described below.

6.5.1 Withering Tea leaves are spread on a mat made of bamboo. The leaves are overlapped so that there are no spaces between them. On cloudless days, the leaves are dried


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in the sun for several hours and then moved indoors. The procedure is repeated for 2–3 days. The leaves are withered also by spreading in a well-ventilated room at a temperature of 29–30°C and a relative humidity of 65–70%, till the buds contain about 30% moisture and leaves about 13%.

6.5.2 Rolling Rolling is done at once before the temperature drops. Rolling is carried out 2–3 times with a suitable pressure.

6.5.3 Firing Bud tea is fired at a temperature of 40–45°C for 20–30 minutes. Leaf tea is fired at a temperature of 70–80°C for 10–15 min until the leaves contain about 6% moisture. The material is stirred gently for uniform firing [17].

6.6 Oolong tea Oolong tea (Figure 6.4) is a semi-fermented tea with special flavour and quality. It is originated in the Fujian province. China derives its name from the Chinese word Wulong, literally means black dragon and symbolizing authority and nobility. The creation time of oolong tea can be traced back to 1855. By combining green and black tea processing procedures, tea farmers in Fujian province invented a new type called oolong tea. Oolong teas are recognized such as wuyi rock tea, red robe tea, iron budha tea, rougui tea, golden key tea etc. Oolong teas are widely consumed in mainland China, Taiwan, Japan, the United Kingdom, America and South-East Asian countries. The processing steps in the manufacture of oolong tea are described below [22].

6.6.1 Plucking A fully matured shoot (a dormant bud and bhanji with 2–3 leaves) is plucked for oolong tea manufacture [22].

6.6.2 Withering Unlike black tea, a special name called Zuoquing, literal meaning green making, is given to withered stage of oolong tea processing. This stage is done in the open air by sunlight. The plucked leaves are spread on bamboo mats (0.5 kg/m2) and exposed to sunlight and the leaves are turned 2–3 times. When the leaves become soft and the total moisture loss reaches 10–20%, the leaves are moved indoor for the next step [22].


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6.6.3 Rotating Rotating causes friction between leaves and disrupts the leaf cells. Most famous or high-grade oolong teas are rotated by hand using a bamboo tray. A special machine designed for rotating withered leaves is now widely used for common oolong tea. Rotating is done indoors at a temperature of 20–25°C and at a relative humidity of 75–85%. The rotating of leaves causes damage to leaf edges and fermentation takes place. The leaf edges turn red at first, gradually spreading to the inner part of leaves. Rotating step lasts for 6–8 h and occurs 5–6 times [22].

6.6.4 Fixing The rotated leaves are immediately subjected to high temperature fixing in order to stop fermentation at the edge and to deactivate the enzyme activity in the green part. The fixing involves pan heating for 3–7 min at 180–220°C [22].

6.6.5 Rolling Rolling is done at once before the temperature drops. Rolling is carried out 2–3 times with suitable pressure. The cell breakage degree is lighter than green or black tea, i.e. about 30%. This is the reason why oolong tea can be brewed repeatedly [22].

Figure 6.4 Oolong tea


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6.6.6 Drying Drying is usually done in two stages. In the first stage, leaves are spread thinly on a bamboo basket or the drying machine and dried quickly at high temperatures. In the second stage lower temperature is used [22].

6.7 Black tea The basic principle of manufacturing black tea (Figure 6.5) is the control of colour change or browning reaction known as “fermentation”. Much of the effort in the tea manufacture goes into controlling timing, rate and degree of this reaction. It is important to note that this is not a true fermentation, but rather an enzymatic oxidation process, and it occurs when the cellular contents (polyphenols and polyphenol oxidase enzymes) are mixed in presence of oxygen. There are many variable parameters in tea processing. The outlines of major steps of black tea processing are presented below [22].

Figure 6.5 Black tea

6.7.1 harvesting Harvesting (Figure 6.6) is not technically a part of the manufacturing process. The harvesting is done manually or mechanically. It is also important to stress that freshly harvested tea shoots are perishable. They can be bruised or


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broken easily by prematurely triggering the fermentation process and causing deterioration in quality. To avoid these problems, it is necessary to begin the manufacturing process as quickly as possible after harvest [22]. Harvesting Withering Rolling / leaf distortion

Fermentation

Frying/drying

Sorting Figure 6.6 Processing of black tea

6.7.2 Withering Freshly harvested shoot contains 75–85% moisture. The moisture level need to be reduced to 50–70% before leaves can be handled properly in the maceration or rolling step that follows. This initial water reduction is called withering and can be accomplished in many ways. In south India where the climate is humid withering is done in enclosed lofts, where as in the north-east, it is done on open-air racks. The most common method is to spread the tea in large, indoor troughs designed to allow airflow through the leaf. Withering with this system is usually done with ambient or slightly heated air, and requires 12–14 hours. The tea must be treated very gently during the withering phase to avoid premature triggering of the oxidation process. Properly withered tea-leaves are very supple and soft to touch. The primary focus of withering is moisture reduction; other chemical changes also occur in the leaf during process. The withered leaves are physically rolled without breaking up excessively [22].

6.7.3 Rolling/ maceration/ leaf distortion The primary purpose of rolling step is to disrupt the cells of tea leaves to mix the substrates (e.g., polyphenols) with the enzymes (e.g., polyphenol oxidase)


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and triggering the fermentation process [23]. Based on the rolling mechanism, there are two main methods of tea manufacture. The first is called orthodox type of manufacture and the other is CTC (crush-torn-curl type). CTC grades are mostly granulated in appearance while orthodox grades are long particles or whole leaf type [22].

Orthodox rolling This traditional type of manufacture (i.e., rolling the withered tea leaves in rollers) has steadily lost favour with traders and consumers because it diffuses slowly, breaks into smaller particles easily while packing and most of all, it brews less cups per kilogram against CTC. Producers also find it more costly to produce. However, this slow process allows the end produce to retain a majority of delicate flavour molecules inherent in the plucked green leaf. Therefore, almost all teas produced in high elevation areas such as Darjeeling, Sikkim, Himachal and Tamil Nadu (Nilgiris) continues to be of the orthodox variety, fetching premium prices. The orthodox method of manufacture accounts for about 20% of the Indian crop, amounting to approximately 160 million kg [22].

CTC This style of manufacturing (i.e., crushing, tearing and curing the tea leaves in between twin metal cylinders with serrated surfaces) has the advantage by being a quick brewer and yielding more cups per kg. In the domestic market, where strong tea liquor is more in demand and more cups per kg are important, this type of manufacture has virtually taken over the demand. In the export market, particularly in the western hemisphere where the tea bags have gained popularity, CTC teas are in demand. In addition, for the tea plantation owner the cost of manufacture is less due to less waste and less caution needed in plucking. However, the CTC process does reduce the delicate natural flavours of tea. In India today, over 80% of tea production is of the CTC type, amounting approximately to a staggering 650 million kg/year [24].

6.7.4 Fermentation Immediately following the maceration or rolling step, fermentation begins. This step is of critical importance, being at a stage where briskness, colour and strength are being developed. Depending on the style of rolling or maceration used, the fermentation process generally requires between 0.75 and 3 hours to accomplish. All teas have optimum ‘fermentation’ time for any given characteristic. Oxygen, temperature and humidity are the key variables that


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are controlled during fermentation. Higher temperatures and a greater supply of oxygen cause things to proceed more rapidly. Humidity is controlled to prevent leaf from drying out. During fermentation the leaf changes colour from green to coppery black. The characteristic tea aroma also develops. It is important to take steps to ensure evenness of fermentation within the tea.

Changes occurring during fermentation During fermentation, following physical changes occur: disappearance of bitter taste of tannin and the development of a pleasant, astringent taste due to oxidation of tannins. The first stage in the fermentation of tea is the enzymatic oxidation of ascorbic acids with the formation of dehydro-ascorbic acid and H2O2. H2O2 and peroxidase then oxidizes the tea tannin. As each molecule of tea tannin takes up one atom of oxygen only in its oxidation and also tea tannin contains the catechol grouping, so the primary product of oxidation of tea tannin is orthoquinone. These orthoquinones are condensed to theaflavins, which are further oxidized to thearubigins (Figure 6.7). Polyphenolic bodies Enzymatic oxidation Orth quinones Condensation Theaflavins (TF) Oxidation Thearubigins (TR) Figure 6.7 Changes during fermentation of black tea

6.7.5 Drying The first objective of a drying process is to arrest fermentation. This is accomplished by exposing the tea to hot air in the first stage of drying operation. The second objective of drying is to reduce the moisture level to 3–4%. There are many approaches to drying. These range from simple batch dryers to very sophisticated fluidized bed designs.

6.7.6 Sorting and fibre removal The final stage of tea processing is the classification of leaf according to the size and removal of stalk and fibre particles. Classification is accomplished by passing the tea over a series of vibrating screens. Stalks and fibre particles are removed electro statically. The final grades of tea are based on the size of


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particles. The major grades, in descending order of size are whole, broken, fannings and dusts. The relative proportion of different grades is primarily the function of the methods used for rolling/ maceration step. Whole leaf teas are produced only through orthodox tea manufacture. The rotovane produces leaf fragments primarily in the broken category. CTC machine produce particles primarily in the fanning size range [23].

6.8 Comparison of tea quality Comparison of the quality of various types (green, green brick, yellow, white, oolong and black) of tea is described in Table 6.1. The parameters include tenderness of fresh leaf, infusion colour, infused leaf, aroma and taste. Table 6.1 Comparison of the quality of various types of tea [17, 22]

Teas

Tenderness of Fresh leaf

Infusion colour

Infused leaf

Aroma

Taste

Green tea

bud

Brilliant green

Jade green

Fresh of Chestnut

Brisk

Green brick Tea

Yellow tea

White tea

bud and 4–6 leaves with some old stalks Leaf tea bud and 4–6 leaves Bud tea – 1 bud and 1–2 leaves

Brownish yellow

Bright Yellow

Bud and 1–2 Light orangish leaves or bud yellow

Hard, Stalk, pine mixed smokes and bluish brown arches flavour

Tender yellow fresh and pure

Plane

Open and mixed

Fresh and pure Flower odour

Oolong tea

Bhanji bud and 2–3 leaves

Golden yellow

Green leaf with yellow margin

Black tea

Bud and 2–6 leaves

Brownish yellow

Brownish orange


Mellow

Plane

Rich and mellow

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7 Chemical composition and pharmalogical, medical properties of tea

7.1 Introduction Tea (Camellia sinensis) is one of the most commonly consumed beverages in the world today. Since ancient time, tea has been regarded as a healthy beverage. In Chinese literature (from Tang Dynasty), tea has been rated as a leading health giving beverage and a cure for many diseases [25]. The health benefits of tea have been known to human civilization for centuries. In earlier days, tea infusion was popular for improving blood flow, detoxification and disease prevention. The types and percentage content of flavonoids (polyphenols) present in tea usually differ depending on the variety of leaf, the environment in which tea is grown, its processing, manufacturing, particle size of ground tea leaves and the infusion prepared. Typically, more than 90% of the total tea phenolic compounds are reported to be flavonoids [25]. However, fresh tea composes of water (75–78%) and dry matter (22–25%). Proximate composition of tea leaves is provided in Table 7.1. Table 7.1 Proximate composition of dry matter of leaves [26]

Components

Percentage

Proteins Free amino acids Alkaloids Polyphenols Sugars Organic acids Lipids Pigments Ash Vitamins Aroma substances

20–30 1–4 3–5 20–35 20–25 1–3 2–6

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