CHAPTER 17

Tea Processing andCarotenoids

Na-Na Li1, Jian-Liang Lu2, Yue-Rong Liang11Zhejiang University Tea Research Institute, Hangzhou, PR China2The Key Laboratory of Horticultural Plant Growth, Development and Biotechnologyof Ministry of Agriculture of China, Hangzhou, PR China

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AbbreviationsCTC crush, tear and curlHPLC high performance liquid chromatographyTOX terminal oxidaseUV ultravioletVDE violaxanthin de-epoxidase

INTRODUCTIONCarotenoids are tetraterpenoid organic pigments in the chloroplasts and chromoplasts of thetea plant. Carotenoids are classified as xanthophylls and carotenes. The former molecules, such

as lutein (xanthophyll), violaxanthin, neoxanthin, and zeaxanthin, contain oxygen, but the

latter, such as a-carotene, b-carotene, are purely hydrocarbon and contain no oxygen. Carot-enoids absorb light energy for use in photosynthesis and protect chlorophyll from photo-

damage, and thus play key roles in tea plants.

Carotenoids have health effects for humans. b-carotene and a-carotene can be converted to

retinal and have vitamin A activity, and the other carotenoids can also act as antioxidants

(Toomey et al., 2010). Lutein and zeaxanthin absorb damaging blue and near-ultraviolet light(Maci, 2010), showing a protective effect against eye diseases such as age-related macular

degeneration.

Carotenoids are an important determinant of tea quality, because many of the quality-relatedflavor volatiles are produced through their degradation during tea processing (Ravichandran,

2002). The sweet floral smells present in black tea are due to the aromatic compounds

resulting from carotenoid breakdown (Borthakur et al., 2008). There are many factors influ-encing the level of carotenoids in tea, including tea cultivar (Wang et al., 2010), environmental

conditions and tea processing (Du et al., 2009).

This chapter describes the variation in carotenoids between various tea cultivars and the effects

of growing seasons and processing of tea on levels of carotenoids in tea.

Tea in Health and Disease Prevention. DOI: 10.1016/B978-0-12-384937-3.00017-3

Copyright � 2013 Elsevier Inc. All rights reserved.

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SECTION 3Manufacturing and Processing

VARIATION IN CAROTENOID LEVEL BETWEEN TEA CULTIVARSAND GROWING SEASONSLutein is the most abundant carotenoid in tea shoots, b-carotene is the next, and neoxanthin

the lowest, with violoxanthin in between (Table 17.1). Composition and level of carotenoidsdiffered significantly between tea cultivars. There are two types of tea cultivar used in

production, namely the normal tea cultivars which have green shoots all the year round, and

the albinism tea cultivars which have albino shoots during early spring season when thetemperature is below 20 �C (Du et al., 2009). The albinism tea cultivars such as Xiaoxueya,

have a very low concentration of carotenoids because the expression of the genes terminal

oxidase (TOX) and violaxanthin de-epoxidase (VDE), which are involved in the biosynthesisof chlorophylls and xanthophylls’ cycle pigments, are suppressed at low temperature (Du et al.,

2009). b-carotene was not detected in the albinism cultivar Xiaoxueya (Table 17.1). Tea plants

have two sources of TOX, a nuclear cytochrome gene and a plastid gene. The nuclear cyto-chrome TOX is an alternative oxidase and participates in carotenoid desaturation in

chromoplasts, in addition to its role during early chloroplast development. Inactivation of the

TOX gene leads to a photobleached plant. Violaxanthin is biosynthesized from zeaxanthin byepoxidation. The suppression of TOX gene expression is responsible for the growth of albino

shoots in the albinism tea cultivar at low temperatures (Du et al., 2009). VDE is responsible for

catalyzing the de-epoxidation of violaxanthin to antheraxanthins and zeaxanthin in thexanthophyll cycle. The suppression of TOX and VDE in the albinism tea cultivar leads to less

accumulation of carotenoids in albino shoots. However, green tea prepared using the albino

tea shoots has a strong umami or palatable taste, because it contains a high concentration ofamino acids, and so consumers like it. Among the normal tea cultivars with green shoots, the

composition of carotenoids varies between cultivars. Fudingdabai, a Camellia sinensis cultivar

with medium sized leaf has higher concentrations of b-carotene, violaxanthin and neoxanthinbut lower lutein, compared to broad-leaf Camellia sinensis var. assamica cultivar Yulan and

small-leaf Camellia sinensis cultivar Longjing-43 (Table 17.1).

Carotenoid concentration changes withmaturity of the tea leaf. Wang et al. (2010) showed that

lutein content was 92.3 and 398.9 mg kg�1 (DW) in second leaf and third leaf on the same

shoot of cultivar Longjing-43.

The level of carotenoids in tea shoots also varies with growing seasons. The total concentration

of carotenoids was highest in the summer and lowest in the spring, with the autumn in

between (Figure 17.1). The carotenoid concentration in the albinism tea cultivar increasedsignificantly in the summer and the autumn, but it is quite low in the spring. Carotenoids play

important roles in photosynthesis in the tea plant by absorbing light energy and protecting

chlorophyll from photodamage. The carotenoid increase in the summer and autumnmight bea hereditable characteristic acquired by the tea plant in adapting to hot and sunny environ-

ments. The suppression in expression of genes relating to carotenoid accumulation wasreversed as the temperature increased to above 20 �C in the albinism tea cultivar (Du et al.,

2009), which is why the total concentration of carotenoids in the albinism cultivar Xiaoxueya

TABLE 17.1 Variation in Level of Carotenoids between Various Tea Cultivars(mean ± SD, n [ 3; mg gL1 FW)a

Cultivar Lutein b-Carotene Violaxanthin Neoxanthin Total

Yulan 161.45 � 6.42 30.33 � 2.47 5.07 � 0.21 5.00 � 0.36 201.85 � 7.36Fudingdabai 86.31 � 1.73 76.32 � 3.86 27.73 � 0.28 13.12 � 0.23 203.48 � 4.80Longjing-43 162.11 � 5.67 31.35 � 2.96 5.56 � 0.43 3.99 � 0.32 203.01 � 5.32Xiaoxueya 8.38 � 0.90 0 2.92 � 0.45 1.30 � 0.01 12.60 � 1.34

aSamples were shoots with two leaves and a bud in the first flush of Spring tea; SD, standard deviation; FW, fresh weight.

(Unpublished)

FIGURE 17.1Variation in of total carotenoids with growing season. Shoots with two leaves and a bud of first flush each season. The errorbar shows standard error (SEM), n ¼ 3 (unpublished).

CHAPTER 17Tea Processing and Carotenoids

increased greatly in the summer and autumn seasons. A lot of aromatic volatiles are degradedproducts of carotenoids (Ravichandran, 2002). This implies that tea shoots grown in the

summer and autumn seasons have the potential to produce teas with stronger aromas.

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CHANGES IN CAROTENOID LEVEL DURING PROCESSINGFOR VARIOUS TEASThe variation in carotenoids depends on both the type of fresh tea leaves used and theprocessing procedure. During tea processing, the level of carotenoids tends to decrease.

In green tea processing, the fresh tea shoots are fixed in a drum-type fixation machine at 200 �Cfor about 5min, rolled in a rolling machine for 30min and finally dried at 120 �C to amoisturelevel about 6% (Liang et al., 1990). For black tea processing, however, the tea shoots are

withered at about 30 �C for more than 6 h and then rolled. The rolled leaves are fermented for

2e3 h at about 30 �C and finally dried. There are studies showing that heating regulates cellredox reactions and the degradation of carotenoids (Achir et al., 2010; Song et al., 2010).

Because many components of carotenoids are sensitive to temperature, heating procedures

such as drying for both green tea and black tea and fixation for green tea have a great impact ontheir levels (Figure 17.2). Oxidations including enzymatic oxidation and auto-oxidation might

also be factors in the decrease in carotenoids. The leaves for green tea and oolong tea are fixed

by heating before rolling, and during this process the oxidase enzymes, including polyphenoloxidase and carotenoid oxidase, are inactivated, resulting in the inhibition of enzymatic

oxidation. The rolling of green and oolong tea aims to make the tea more compact, and to

allow the chemicals in the tea leaf to be easily extracted during the preparation of tea liquor.However, the rolling of black tea bruises the tea leaves, disrupting the leaf cells and allowing the

tea polyphenols to contact polyphenol oxidase and oxygen, which promotes the oxidation of

tea polyphenols and formation of red pigments (thearubigins) and yellow pigments(theaflavins) (Li et al., 2010). Both enzymatic oxidation and auto-oxidation of carotenoids may

take place during black tea rolling because the leaf enzymes, including carotenoid oxidase, are

not inactivated. This is the reason that carotenoid concentrations decrease more quickly inblack than in green tea. Oxidation of carotenoids also takes place during black tea fermenta-

tion. This suggests that severe rolling and high-temperature drying should be avoided in order

to maintain a high concentration of carotenoids in the final tea products.

Carotenoid concentration in tea increases with the maturity of the tea leaf (Wang et al., 2010).

Fresh tea leaves for oolong tea processing are always mature shoots with four leaves anda dormant bud, and its carotenoid concentration is higher than the shoots with two leaves and

FIGURE 17.2Changes in total carotenoids during processing of various teas. 1. Fresh tea shoots, with four leaves and a dormant budfrom cultivar Camellia sinensis Maoxie for oolong tea, with two leaves and a bud from cultivar Camellia sinensis Zhenong-139

for green tea and black tea; 2. withered leaf for black tea and oolong tea and fixed leaf for green tea; 3. rolled leaf for black tea

and green tea, fixed leaf for oolong tea; 4. fermented leaf for black tea and rolled leaf for oolong tea; 5. dried tea. The error bar

shows standard error (SEM), n ¼ 3 (Unpublished).

TABLE 17.2 Change

Sample Lu

Fresh leaf 83(10

Withered leaf 68(81

Rolled leaf 42(50

Fermented leaf 36(43

Dry tea 3(4.

aThe materials were shoots wit

SD, standard deviation; DW, d

(Unpublished).

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210

a bud that are used for green tea and black tea processing (Figure 17.2). During oolong tea

processing, the picked leaves are partially dried in sunshine for 10 min, and then withered at

room temperature for about 12 h, during which time the leaves are tossed by hand for 1 minevery other 2 h. The withered leaves are fixed in a drum-type fixation machine at 200 �C for 5

min. The fixed leaves are rolled in a rolling machine for 30 min and finally dried at 120 �C to

a moisture level of about 6% (Chen et al., 2011). The oolong tea processing procedure issimilar to that of green tea. The difference in the maturity of tea shoots is the major factor

giving oolong tea a higher level of carotenoids than green tea or black tea.

The changes in various components of carotenoids might be related to their sensitivity to

temperature and oxidative conditions. When the same batch of fresh tea shoots with two leaves

and a bud from cultivar Camellia sinensis Zhenong-139 was processed into green tea and blacktea respectively, the degradation of neoxanthin was the least, and b-carotene the next, based on

the percentages of residue carotenoids. More than 98% of violaxanthin in fresh leaf is degraded

during green tea and black tea processing (Tables 17.2e17.3). Because the concentration of

s in Carotenoids During Black Tea Processing (mean ± SD, n [ 3; mg gL1 mg gL1, DW)a

tein b-Carotene Violaxanthin Neoxanthin Total

3.26 � 62.820)

537.01 � 49.09(100)

213.59 � 3.00(100)

38.80 � 1.21(100)

1622.66 � 126.28(100)

2.23 � 23.26.87)

478.52 � 14.18(89.11)

166.35 � 6.07(77.88)

23.95 � 2.20(61.73)

1351.04 � 40.83(83.26)

2.90 � 4.20.75)

315.88 � 10.54(58.82)

121.89 � 5.56(57.07)

17.06 � 0.28(43.97)

877.74 � 18.48(54.09)

5.74 � 38.50.89)

279.67 � 9.73(52.08)

94.43 � 6.66(44.21)

15.09 � 0.50(38.89)

754.93 � 39.17(46.52)

9.18 � 3.3470)

47.22 � 1.77(8.79)

0.89 � 0.04(0.42)

3.56 � 0.34(9.18)

90.86 � 13.33(5.59)

h two leaves and a bud from cultivar Zhenong-139. Data in brackets is the percentage compared to that in fresh tea leaf.

ry weight.

TABLE 17.3 Changes in Carotenoids During Green Tea Processing (mean ± SD, n [ 3; mg gL1, DW)

Sample Lutein b-Carotene Violaxanthin Neoxanthin Total

Fresh leaf 833.26 � 62.82(100)

537.01 � 49.09(100)

213.59 � 3.00(100)

38.80 � 1.21(100)

1622.66 � 126.28(100)

Fixed leaf 627.92 � 62.65(75.36)

487.91 � 46.97(90.86)

140.65 � 4.81(65.85)

34.37 � 2.65(88.58)

1290.84 � 107.07(79.55)

Rolled leaf 499.65 � 19.75(59.96)

420.72 � 32.35(78.34)

108.93 � 6.78(50.91)

26.85 � 0.94(69.20)

1056.14 � 37.07(65.09)

Dry tea 117.55 � 4.13(14.11)

141.66 � 9.43(26.38)

2.68 � 0.09(1.25)

10.68 � 0.49(27.53)

272.57 � 14.13(16.80)

aThe materials were shoots with two leaves and a bud from cultivar Zhenong-139. Data in brackets is the percentage compared to that in fresh tea leaf

SD, standard deviation; DW, dry weight.

(Unpublished).

CHAPTER 17Tea Processing and Carotenoids

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lutein and b-carotene are higher than violoxanthin and neoxanthin in fresh leaf, they are the

major components of carotenoids in dry tea (Tables 17.2e17.3).

VARIATION IN CAROTENOID LEVEL BETWEEN VARIOUS KINDSOF TEACarotenoid concentration of made tea depends on cultivar, production season, maturity of tea

shoot and processing procedure. These factors differ between various kinds of tea, leading todifferences in carotenoid levels in the final teas. Generally, oolong tea which is processed using

mature tea shoots has the highest level of carotenoids, the fully fermented black tea has the

lowest, and green tea is in between (Table 17.4). However, Dahongapo, a kind of oolong teaproduced in the Wiyu Mountains in north Fujian Province of China has a very low level of

carotenoids, even though it is processed with mature tea shoots as Tieguanyin and

Fenghuangdacong. This might be related to its special drying procedure, in which the tea isbaked for many hours using a charcoal fire. This agrees with the conclusion that processing

procedure, especially drying, has great impact on carotenoid levels. In green tea samples,

carotenoid concentrations in Japanese Sencha, a steam-fixed green tea, is twice as high as thosein the Chinese green teas Huangshan Maofeng and Longjing.

TABLE 17.4 Concentration of Carotenoids in Various Teas (mean ± SD, n [ 3; mg gL1, DW)a

Type of TeaCommercialTea Name Lutein b-Carotene Violaxanthin Neoxanthin Total

Green tea HuangshanMaofeng

274.73 � 25.97 208.30 � 8.84 10.86 � 1.06 18.87 � 2.11 512.75 � 35.81

Longjing 293.75 � 4.80 201.89 � 9.27 10.30 � 0.24 17.49 � 0.33 523.42 � 10.53JapaneseSencha

703.29 � 39.40 626.96 � 19.87 7.60 � 0.70 18.57 � 0.47 1356.42 � 48.13

Black tea Keemen blacktea

261.83 � 7.69 204.16 � 3.89 13.68 � 1.07 24.33 � 0.47 504.01 � 4.83

Assam brokenblack tea

124.05 � 3.68 43.50 � 2.14 24.83 � 1.35 33.80 � 0.94 226.17 � 2.25

Sri LankaCongous tea

315.52 � 17.87 236.03 � 4.73 21.94 � 0.57 23.95 � 2.46 597.43 � 17.79

Oolong tea FenghuangDancong

527.35 � 11.71 547.46 � 20.60 17.12 � 1.11 21.56 � 1.74 1113.50 � 9.10

Tieguangyin 1103.30 � 40.93 982.99 � 26.15 29.87 � 2.33 31.29 � 1.02 2147.45 � 59.83Dahongpao 23.55 � 2.08 152.67 � 5.21 1.29 � 0.13 1.94 � 0.13 179.45 � 5.00

aThe samples were purchased from market. SD, standard deviation; DW, dry weight.

(Unpublished).

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Alternatively, this difference may come from their different fresh tea leaves and fixationprocedures. Japanese Sencha is processed using tea shoots with three or four leaves and a bud,

which are more mature than those used to process Huangshan Maofeng and Longjing. During

the fixation procedure, Japanese Sencha is fixed by steam for about 10 seconds, while thefixation of Huangshan Maofeng and Longjing lasts about 5 min or longer. Keemen black tea

and Sri Lanka Congous black tea are leaf teas, while Assam broken black tea is a CTC (crush,tear and cur) type broken black tea which is severely crushed, torn and curled during the

rolling stage to accelerate the leaf fermentation. The oxidation of carotenoids in the broken

black tea might be more dramatic than that in the leaf black tea. This explains why Assambroken black tea has fewer carotenoids than Keemen black tea and Sri Lanka Congous black

tea. Concentration of violaxanthin was the least abundant carotenoid in the tea products

(Table 17.4) although it is present at higher levels than neoxanthin in fresh tea leaf(Tables 17.1e17.3), suggesting that neoxanthin is more-easily degraded than violaxanthin

during tea processing.

SUMMARY POINTS

l The concentration of carotenoids in fresh tea leaf varies with tea cultivar. The albinism tea

cultivar has a very low level of carotenoids in spring.

l Carotenoid levels in fresh tea shoots varies with growing season, being highest in summerand lowest in spring, with autumn in between.

l Carotenoid content in tea leaf increases with the maturity of tea shoots.l Tea processing leads to a decrease in carotenoid content, especially the drying process.

l Generally, oolong tea has a higher concentration of carotenoids than green tea or black tea.

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