本研究以高效能液相層析法定量分析不同季節採摘的茶菁﹙台茶12號）於文山(條型)包種茶製程中兒茶素（catechins）、黃酮醇 (flavonols)、酚酸 (phenolic acids)、茶黃質(theaflavins, TFs)等多元酚類及植物鹼(alkaloids)含量之變化。結果發現，各種多元酚類化物及植物鹼之含量於製程中有不同的變化情形。
兒茶素包括(-)-epicatechin﹙EC﹚、(-)-epigallocatechin (EGC)、(-)-epicatechin gallate (ECG)、(-)-epigallocatechin gallate (EGCG)及(+)-gallocatechin gallate (GCG)，各存在量分別為1.91-7.30mg/g (乾葉重)、 16.01-53.51mg/g、12.32-31.32mg/g、46.56-106.1mg/g及10.20-74.28mg/g。不同季節茶菁之 EC、EGC、ECG、EGCG 及 GCG 在包種茶製造時之變化趨勢略同，但變化程度有所差異，以冬茶GCG含量變化最明顯。日光萎凋後兒茶素平均增加 7%，室內萎凋期間則減少7%，炒菁後兒茶素含量大幅增加，除春茶外，夏茶、秋茶和冬茶之兒茶素含量皆增加約 30%。
茶菁中的黃酮醇有 myricetin 及 quercetin，以醣的形式存在，經酸水解成其配醣基﹙aglycone﹚後進行定量分析，各種的存在量分別為 2.32-3.88 mg/g 及1.45-2.22 mg/g，於製程中黃酮醇之變化不大，且無規則性。
茶黃質為多元酚類之氧化產物，茶菁中其含量極微，在 0.5 mg/g 以下。日光萎凋時就存在，在室內萎凋時漸增，於第二次攪拌後漸減，第三次攪拌後又再度增加，炒菁後則有明顯減少現象（除 TF4）損失率達50%以上。
酚酸包括 gallic acid 與 theogallin，二成分於製成中變化情形不同，前者於茶菁製成包種茶後含量平均減少 81%，而後者於製程中則無顯著變化。
咖啡因（caffeine）與可可鹼(theobromine)為茶葉中的植物鹼，此些化學成分於製茶過程中之變化不大，屬穩定性的成分。茶菁中咖啡因存在量為17.59-27.95mg/g；可可鹼為0.16-0.93m

The contents of catechins, flavonols, phenolic acids, theaflavins and alkaloids during the processing of pouchong tea (Taiwan Tea No. 12) were determined by HPLC. It was found that each stage of pouchong tea processing would affect the amounts of polyphenols and alkaloids.
Tea catechins are composed of (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG) and (-)-gallocatechin gallate (GCG). They were present at 1.91-7.30mg/g (dried leaves), 16.01-53.51mg/g, 12.32-31.32mg/g, 46.56-106.10mg/g and 10.20-74.28mg/g, respectively. The trends of catechins of changes during pouchong tea processing were similar for the tea leaves picked at different seasons. However, the extents of the changes were different, especially GCG in winter tea. On the average, catechins increased 7% after solar withering and decreased 7% after indoor withering. Catechins increased about 30% after fixing except spring tea.
Flavonols in teas are myricetin and quercetin, existed as their glycosides. Quantitative analysis of tea flavonols was performed by analyzing their aglycones after acid hydrolysis. Myricetin and quercetin were found to be 2.32-3.88mg/g and 1.45-2.22mg/g respectively. Two flavonols did not show significant changes during processing of pouchong tea.
Phenolic acids are mainly consisted of gallic acid and theogallin. After fixing, the amount of gallic acid reduced 81% on an average. But the change in theogallin was insignificant during tea processing.
Theaflavins (TFs) are the well-defined group of flavonoid oxidative products. They existed in trace amount in tea leaves, usually less than 0.5mg/g. Theaflavins were found in fresh tea leaves before solar withering, then gradually increased during indoor withering. They were gradually reduced after the 2nd rotating and increased again after the 3rd rotating. After fixing, TFs reduced significantly (except TF4), and the loss exceeded 50%.
Caffeine and theobromine are the alkaloids in tea. Variations in alkaloids contents in tea leaves during pouchong tea processing were insignificant. The amounts of caffeine and theobramine in tea leaves were found to be 17.59-27.95mg/g and 0.16-0.93mg/g

目 錄
中文摘要
英文摘要 頁次
壹、 前言 1
貳、 文獻整 2
一、 台灣茶葉簡介 2
（一） 茶樹品種 2
（二） 台灣茶業 2
（三） 特色茶 3
二、 文山包種茶 6
三、 茶葉之化學組成 7
（一） 黃烷醇 10
（二） 黃酮醇及其配醣體 12
（三） Flavones 12
（四） 酚酸及縮酚酸 14
（五） 酚類氧化物 14
四、 茶葉製程之生物化反應 14
（一） 製造時生化反應 14
（二） 茶葉酚類化合物之變化 19
五、 茶葉化學組成分的重要性 24
（一） 成茶感官品質方面 24
（二） 食品機能性方面 25
六、 茶葉主要化學成分的分析方法 29
參、 材料與方法 31
一、 試驗材料 31
（一） 試驗茶菁樣品 31
（二） 試藥與試劑 31
（三） 儀器設備 33
二、 試驗流程 35
（一） 採樣次序 35
（二） 成分分 37
三、 試驗方法 38
（一） 樣品前處理 38
（二） 樣品之萃取 38
（三） 總酚類含量之測定 39
（四） 茶葉萃取液之高效能液相層析 39
（五） 茶黃質標準品之製備 41
（六） 茶黃酮醇醣類LC-MS 分析 43
（七） 水分含量之測定 43
（八） 統計分析 44
肆、 結果與討論 45
一、 包種茶中多元酚類及植物鹼分析方法之建立 45
（一） 兒茶素、沒食子酸與植物鹼 45
1. 水萃取條件之探討 45
2. 高效能液相層析 47
3. 質譜分析 49
（二） 茶黃酮醣類 49
1.LC-MS分析 49
2.酸水解試驗 53
3.酸水解產物（黃酮醇）高效能液相層析 56
（三） 茶黃質 56
1. 層析前處理 56
2. 高效能液相層析 60
二、 包種茶製程中總酚含量之變化 60
三、 包種茶製程中各多元酚類與植物鹼含量之變化 65
（一） 兒茶素（catechins） 65
（二） 酚酸（phenolic acids） 73
（三） 黃酮醇(flavonols) 76
（四） 茶黃質(theaflavins) 76
（五） 咖啡因(caffeine)與可可鹼(theobromine)80
四、 不同季節茶葉各多元酚類含量之差異性 83
五、 包種茶茶菁與成茶主要成分含量之比 85
伍、結論 87
陸、參考文獻 89
柒、附錄 98

中文參考文獻
丁一倪. 1981. 茶葉品質鑑定方法科學化之研究 第二報茶葉中兒茶素及葉綠素與茶葉品質關係研究.中國農業化學會誌19(3-4):181-189.
王澤農,汪琢成,林鶴松,蕭 祥,潭淑宜,謝曉風,徐梅生,王 生 和 周靜舒. 1984a. 第一章 茶葉中的酵素。茶葉生物化學(第二版)。農業出版社出版. 中國 北京
王澤農,汪琢成,林鶴松,蕭 祥,潭淑宜,謝曉風,徐梅生王 生 和 周靜舒. 1984b. 第八章 紅茶製造生物化學.茶葉生物化學(第二版).農業出版社出版 中國 北京
甘子能 1981b. 茶葉多元酚類成分(之二)：製茶過程中多元酚類的轉變.食品工業.13(7):10-16
甘子能 和 林義恆.1996. 認識台灣的包種茶.茶業改良場編印
甘子能. 1981a. 茶葉多元酚類成分.食品工業.13(1):10-18
吳振鐸,葉速卿 和 鄭觀星.1975.不同製茶種類對兒茶素含量的影響.中國農業化學會誌.13:159-168.
吳振鐸.1985.台灣茶葉分類.台灣茶葉研究彙報.4:155-158.
阮逸明,張如華 和 張連發.1989.不同烘焙溫度與時間對包種茶化學成分與品質之影響.台灣茶葉研究彙報.8:71-82.
阮逸明.1996.台灣茶葉簡介.茶業改良場編印
阮逸明.1998.台灣茶葉市場產銷概況.市場概況.148:25-27.
范增平.1992.台灣主要茶葉.台灣茶葉發展史.pp236-241.
高碧穗,陳清泉,施玲玲 和 程竹青.1996.酵素處理對烏龍茶湯品質的影響.食品科學.23(3):356-366.
區少梅.蔡永生 和 張如華.1988.包種茶酚類化物分析方法之比較與評估.台灣茶葉研究彙報.7:43-61.
張如華 和 李敏雄.1994.萎凋及發酵之溫度與時間對包種茶品質之影響.中國農業化學會誌.32(5):469-485.
陳右人.1995.茶樹品種與育種介紹.茶葉技術推廣手冊.pp7-10.
陳英玲.1989.茶多元酚氧化之研究.台灣茶葉研究彙報.8:83-90
陳惠英 和 顏國欽.1996.不同季節價位和沖泡次數之烏龍茶的抗突變性及其主要成分含量.中國農業化學會誌4:185-194.
程竹青.1995.台灣茶飲料之發展趨勢.食品資訊.7:15-22.
楊名翔,游銅錫,林麗雲 和 張基郁.1997. 熱處理對烏龍茶非揮發性組成及茶湯色澤之影響.中華生質能源學會會報.16:109-115
葉速卿 和 吳振鐸 .1978.半發酵茶製造過程中茶葉主要成分之變化與成茶品質之關係研究.中國農業化學會誌.16:123-131.
蔡永生,區少梅 和 張如華.1990.不同品種包種茶官能品質與化學組成之特徵與判別分析. 台灣茶葉研究彙報.9:79-97.
蔡永生和張如華. 1986.茶葉可溶成分萃取之研究.台灣茶葉研究彙報.5:155-158.
蘇正德,蔡文騰,張基煌 和 蘇女淳.1991.茶湯與茶渣之兒茶酚含量及抗氧化性之調查研究.食品科學.18:234-248.
Bailey, G. and Nursten, H. E. 1993. The chemical oxidation of catechins and other phenolics: A study of the formation of black tea pigments.J. Sci. Food Agric. 63: 455-464.
Bailey, R. G., Mcdowell, I. and Nursten, H.E. 1990. Use of HPLC photodiode-array detector in a study of the nature of a black tea liquor. J. Sci. Food Agric. 52: 509-525.
Bailey, R.G. and Nursten, H. E. 1994. A liquid chromatography-mass spectrometry study of black tea liquor using the plasmaspray. J. Sci. Food Agric. 66: 203-208.
Bailey, R.G., Mcdowell,I. and Nursten, H.E.1990. Use of an HPLC photodiode-array detector in a study of the nature of a black tea liquor. J. Sci. Food Agric. 52: 509-525.
Balentine, D.A., Wiseman, S. and Bouwen, L.C.M. 1997. The chemistry of tea flavonoids. Critical Reviews in Food Sci. and Nutri. 37(8): 693-704.
Caan, B.J. and Golhaber, M.K. 1989. Caffeinated beverages and low birthweights:A case-control study. Am. J. Pblic. Health. 79: 1299-1300.
Cela, R., Lores, M. and Garcia, C.M. 1992. Applicability of a postcolumn reactor in the liquid -performance of chromatograph of 34 polyphenolic compounds with UV detection. J. of Chromagra. 626: 117-126.
Chen, C.W., Chang, Y.W. and Hwang, L. S. 1998. Rapid analysis of theaflavins by high performance liquid chromatograph/atmospheric pressure chemical ionization mass sepectrometry. J. of Food and Drug analysis. 6(4): 713-718.
Cheng, S., Wang, Z., Ho, C.T. 1988. Pharamacological effects of teas in current mediciene in china Beijing.The people''s Medical Publishing House: Beijing.pp165-172.
Chu, D.C. and Juueja, L.R. 1997. Chap2.General chemical composition of green tea its infusion In"green tea"p12-22, CRC press.
Cilliers, J.L., Singleton V L 1991. Characterisation of the products of nonenzymic autoxidative phenolic reactions in a caffeic acid mode system. J. Agric. Food Chem. 39: 1298-1303.
Cloughley, J. B. 1980. The effect of temperature on enzyme activity during the fermentation phase of black tea manufacture. J. Sci. Food Agric. 31: 920-923.
Coggon, P., Moss, G.A., Graham, H.N. and Sanderson,G.W. 1973. The biochemistry of tea fermentation: oxidative degallation and epimerisation of tea flavanol gallates. J. Agric. Food Chem. 21: 727-733.
Dalluge, J.J., Nelson, B.C., Thomas, J.B. and Sander, L.C. 1998. Selection of colunm and gradient elution system for the separation of catechins in green tea using high-preformance liquid chromatography. J. of chromatography A. 793: 256-274.
Dix, M.A., Fairey, C.J., Millin, D.J. and Swaine, D. 1981. Fermentatioon of tea in aqueous suspension influence of tea peroxidase. J. Sci. Food Agric. 32:920-932.
Finger, A. and Engelhardt, U.H. 1991. Flavonol glycoside in tea kaempferol and quercetin rhamnodiglucoside. J. Sci. Food Agric. 55: 313-321.
Finger, A. 1994. In-vitro studies on the effect of polyphenol oxidase and peroxidase on the formation of polyphenolic black tea constituents. J. sci. Food Agric. 66:293-305.
Finger, A., Kuhr, S. and Engelhardt, U.H. 1992. Chromatography of tea constituents. J.of chromatography. 642: 293-315.
Forrest, D.1985. The World Trade: A survey of the production, Distribution and Consumption of tea; Woodhead- Faulkner, Ltd. :Cambridge, Uk
Fujiki, H., Yoshizawa, S.,Horiuchi,T., Suganuma,M.,Yatsunami, J., Nishiwaki, S., Okabe, S., Nishiwaki-mstsushima, R., Okuda, T. and Sugimura, T. 1992. Anticarinogenic effects of (-)-epigallocatechin gallate. Prev.Med. 21: 503-509.
Goto,T.,.Yoshida,Y.,Kiso,M. and Nagashima,H. 1996. Simultaneous analysis of individual catechins and caffeinein green tea. J. of Chromatography A. 749: 259-299.
Gulati, A and Rarindranath, S.D. 1996. Seasonal variations in quality of kangra tea (camellia sinensis(L) O Kuntz) in himachal pradesh. J. Sci. Food Agric. 71: 231-236.
Hahlbrock, K. and Griseback, H. 1979. Enzymic controls in the biosynthesis of lignin and Flavonoid. Ann. Rev. Plant physiol. 30: 105-130.
Hara,Y. 1994. Chap3.Prowal, phylactic Functions of tea polyphenols. In" Food Phytochemicals for Cancer Prevention II". p34-50, American chemical society press.
Hara, Y., Luo, S-J., Wickremasinghe, R.L. and Yamanishi, T. 1995a. Chemical composition of tea. Food Rev. Int. 11(3): 437
Hara,Y.,Luo,S-J., Wickremasinghe, R.L. and Yamanishi, T. 1995b. Biochemistry of processing black tea. Food Rev. Int.11(3): 457-471.
Hertog, M.G.L., Hollman, P.C.H. and Venema, D.P. 1992. Optimization of a quantitative HPLC determination of potentially anticarcinogenic flavonoids in vegetables and fruits. J. Agric. Food Chem. 40: 1591-1598.
Hibino, M. and Sakanaka, S. 1997. Deodorizing effect of green tea extract In "Chemistry and applications of green tea". p123-127. CRC press.
Hicks, M.B., Hsieh, Y.-H.P. and Bell, L.N. 1996.Tea preparation and its influence on methylxanthine concentration. Food Research International. 29:325-330.
Ho, C-T., Ferraro, T., Chen, Q.Rosen, R.T. and Huang, M.T. 1994. Chap1..Phytochemicals in tea and rosemary and their cancer-preventive properties In " Food Phytochemicals for Cancer Prevention II".p2-19,American chemical society press.
Honda, M., Nanjo ,F. and Hara, Y. 1994. Chap9.Inhibition of saccharide degestive enzymes by tea polyphenols In" Food Phytochemials for Cancer Prevention II". p83-89, American chemical society press.
Hirose, M., Akagi, K., Hasegawa, R., Yaono, M., Satoh, T., Hara, Y., Wakabayashi, K. and Ito, N. 1995. Chemoprevention of 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (phIP)-induced mammary gland carcinogenesis by antioxidants in F344 female rats,Carcinogenesis. 16: 217
Ishihara, N. and Akachi, S. 1997. Chap13.Green tea extract as a remedy for diarrhea in farmraised calves In" Chemistry and applications of green tea.p137-144.CRC press.
Jimenez, M. and Garcia-Co rmona, F. 1999. Oxidation of the Flavonol quercetin by polyphenol oxidase. J. Agric. Food Chem. 47: 56-60.
Julkunen-Titto, R. 1985 Phenolic constituents in the leaves of northern willows: methods for the analysis of certain phenolics. J. Agric. Food Chem.33: 213-217.
Kada, Y., Kaneko, K., Matsuzuki, S., Matsuzuki, T. and Hara, Y. 1985. Mutation Res.150: 127-132.
Kalita, J.N. 1992. Some aspects of chemistry in the production of tea in relation to mineral nutrition of boron and manganese under field and green house conditions.Ph.D. thesis submitted to Dibrugarh University.
Katiyar, S., Agar/wal, R., Wood, G.S., Mukhtar, H. 1992. Cancer Res. 52: 3875-3879.
Khan, S.G., Katiya, S.K., Agarwal, R. and Mukhtar, H. 1992. Cancer Res.52: 4050-4052.
Koketsu, M. 1997. Chap4.Antioxidative activity of tea polyphenols. In "Chemistry and applications of green tea. p37-50 CRC press.
Liang, Y.R., Lin, Z.S., Xu, Y.R. and Ho, Y.L. 1990. A study on chemical composition of two special green tea ( Camellia sinensus). J. Scim. Food Agric. 53: 541-548
Lin,.J.-k., Lin, C.-L., Liang, Y.-C., Lin-Shiau, S.-Y. and Juan, I-M.1998. Survey of catechins,gallic acid , and methylxanthins in green ,oolong, pu-erh, and black teas. J. Agric. Food Chem. 46:3635-3642.
Lin, Y.Y. 1993. Characterization of flavonoids by liquid chromatography tandem mass spectrometry. J of chromagra. 629: 389-393.
Michael, G.L., Hollman, P.C.H. and Putte, B.V.D. 1993. Content of potentially anticarcinogenic flavonoids of tea infusions, wines, fruit juices. J. Agric. Food Chem. 41:1242-1246
Mahanta, P.K., Boruah, S.K.,Boruah, H.K. and Kaltia, J.N. 1993. Changes of polyphenol oxidase and peroxidase activities and pigment composition of some manufactured balck tea(camellia sinensis L.). J. Agric. Food Chemphic .41: 272-276.
Mahanta, D.K. and Baruah, S. 1989. Relationship between process of withering and aroma characteristics of black tea. J. Sci. Food Agric. 46: 461-468.
Miller, A.R., Kelley, T.J. and Mujer, C.V. 1990. Anodic peroxidase isoenzymes and polyphenoloxidase activity from cucumber fruit: tissue and substrate specificty. Phytochemistry.29:705-709
Mills, J.L., Holmes, L.B., Aarons, J.H., Simpson, J.L., Brown, Z.A., Jovanovic-peterson, L.G., Conley, M.R., Graubard, B.I., Knopp, R.H. and Metzger, B.E. 1993. Moderate caffeine use and the risk of spontaneous abortion and intrauterine growth retardation. JAMA. 269: 593-597.
Mohr, H. and Schopfer, P. 1995. Chap 18 Biosynthetric metabolism in "plant physiology " pp275-283. Spriger press London.
Nakane, H., Hara, Y. and Ono, K. 1994. Chap5.Tea polyphenls as a novel class of inhibitors for human Immunodeficiency In" Food Phytochemicals for Cancer Prevention II". p56-64, American chemical society press.
Nanjo, F., Hara, Yand Kikuchi, Y. 1994. Chap8.Effects of tea polyphenols on blood rheology in rats fed a high-fat diet In" Food Phytochemials for Cancer Prevention II". p76-82. American chemical society press.
Owuor, D.O. and Obanda, M.1998. The change in black tea quality due to variations of plucking standard and fermentation time. Food Chem. 61(4): 435-441.
Price, K. R., Rhodes, M.J.C. and Barnes, K.A. 1998. Flavonol glycoside content and composition of tea infusions made from commercially available teas and tea products. J. Agric. Food Chem.46: 2517-2522.
Roberts, E.A.H. and Russell, G.R. 1957. Oxidation of gallic acid and gallic acid ester to aconitic acid .Chem.Ind. (London).1598-1599.
Robertson, A. 1983. Effects of physical and chemical conditions on the in vitro oxidation of tea leaf catechins. Phytochemistry. 22(4): 889-896.
Rossignol, A.M. and Bonnlander, H. 1990. Caffeine-containing beverages , total fluid consumption,and premerstrual syndrome,Am.J.Public. Health.80: 1106-1110.
Rossignol, A.M., Zhang, J., Chen, Y. and Xiang, Z. 1989. Tea and premenstrual syndrome in the people''s republic of china. Am. J. Public. Health.79: 111-118.
Ruch, R.J., Cheng, S.-J. and Klauning, J.E. 1989. Prevention of cytotoxicity and inhibition of intercellular communicantion by antioxidant catechins isolated from chainese tea.Carcinogenesis.10: 1003-1008.
Sakanaka, S. 1997. Chap 8.Green tea polyphenols for prevention of dental caries. In"Chemistry and applications of green tea. p87-101. CRC press.
Sakanaka, S. and Yamamoto, T. 1997. Chap9.Inhibitory effects of green tea polyphenols on growth and cellular adherence of a periodontal disease bacterium, porphyromonas gingivalis. In"Chemistry and applications of green tea.p1 In"Chemistry and applications of green tea.p103-108.CRC press.
Sanderson, G.W., Berkowitz, J.E., Co, H. and Graham, H.N. 1972 .Biochemistry of tea fermentation :products of the oxidation of tea flavanols in a model tea fermentation system. J. Food Sci.37: 339-404.
Siewek, F. and Galensa, R. 1984. High-performance liquid chromatographic determination of the degree of glycosidation of flavonols by use of an ultra-violet diode-array detector. J. of chromatogr. 294: 385-389.
Spiro, M. and Jago,D. 1982. Kinetic and equilibra of tea infusion.part III: rotating disc experiment interpreted by a steady-state model. J. Chem. Soc. Faraday Trans.I. 78: 295-305.
Takino, Y., Imagawa, H., Horikawa, H., and Tanaka, A. 1964. The mechanism of the oxidation of a reddish-orange pigment and its spectral relation to some benzotropolone derivatives. Agric. Biol. Chem.28:64-71.
Takino, Y., Imagawa, H., and Tanaka, A. 1964. The mechanism of the oxidation of a reddish-orange pigment and its spectral relation to some benzotropolone derivative. Agric. Biol. chem. 28: 64-71.
Ullah, M.R., Bordoloi, A.K. and Gogoi, N. 1986. Hastening of leaf senesrence in the Processing of green tea leaf to black tea. J. Sci Food Agric. 37: 1042-1044.
Ullah, M.R., Gogoi, N. and Baruah, D. 1984. The effect of withering on fermentation of tea leaf and development of liquor characters of black tea.J. Sci. Food Agric. 35: 1142-1147.
Wang, Z.Y., Cheng, S.J., Zhou, Z.C., Athar, Z.C., Khan, W.A., Bickers, K.R. and Makhtar, H. 1989. Antimutagenic activity of green tea polyphenols. Mutat. Res. 223:273
Wellum, D.A. and Kirby, W. 1981. High-performance liquid chromatographic assay for theaflavins. J. of chromatogra.206:400-406.
WHO,1988. Internation agency for research on carcer:coffee,tea mate,methylxanthines and methyglyoxal.JARC Mongor.Eval. Carcinog.Risk Hum.Lyom.p207.IARC press
Wilcox, A.,Dehoog, J.V. and O''connor, D.H. 1988. Influence of caffeine consumption on carcinomatous and normal mammary gland development in mice. Cancer Res. 48: 2078-2082.
Wiseman, S.A., Balentine, D.A. and Frei, B. 1997 .Antioxidants in tea. Critical Reviews in Food Sci. and Nutri.37(8): 705-718.
Wlliam, E.P. and Spitzer, J.C. 1994. The kinetics of extraction of individual flavanols and caffeine from a japanese green tea (Sen Cha Uij Tsuyu) as a function of temperture. Food chem. 50: 19-23.
Yang, C.S. and Wang, Z.-Y. 1993. Tea and cancer. Journal of the National Cancer Institute.85: 1038.
Yang, G.-Y., Liu, Z., Seril, D.N., Liao, J., Ding, W., Kim, S., Bondoc, F. and Yang, C.S. 1997. Black tea constituents, theaflavins, inhibit 4--(methyl-nitrosmaino)-1-(3-pyridyl)-1- butanone(NNk)-induced lung tumorigensis in A/J mice. Carcinogenesis in press.
Yen, G-C and Chen, H-Y. 1995. Antioxidant activity of various tea extracts in relation to their antimutagenicity. J. Agric. Food Chem. 43: 27-32.
Yen, G-C. and Chen, H-Y. 1994. Comparson of antimutagenic effect of various tea extracts (green, oolong, pouchong, and black tea). Journal of Food Protection.57(1):54-58.
Yen, G-C. and Chen, H-Y. 1996. Relationship between antimutagenic activity and major components of various teas. Mutagenesis.11: 37-41.