Comparative Analysis of the Antioxidant and Free-Radical Scavenging Activities of Different Water-Soluble Extracts of Green, Black and Oolong Tea Samples  

作　　者：Jesús Tejero Sara Gayoso Irma Caro Damián Cordoba-Diaz Javier Mateo José E. Basterrechea Tomás Girbés Pilar Jiménez 

机构地区：[1]Nutrició n y Bromatologí a, Facultad de Medicina and CINAD (Centro de Investigació n en Nutrició n, Alimentació n y Dietética Edificio Lucia-Parque Cientí fico), Universidad de Valladolid, Valladolid, Spain [2]Farmacia y Tecnologí a Farmacéutica, Facultad de Farmacia and IUFI (Instituto Universitario de Farmacia Industrial), Universidad Complutense de Madrid, Madrid, Spain [3]Higiene de los Alimentos y Tecnologí a, Facultad de Veterinaria, Universidad de Leó n, Leó n, Spain

出　　处：《Food and Nutrition Sciences》2014年第22期2157-2166,共10页食品与营养科学（英文）

摘　　要：Extracts of 40 green, black or oolong high quality tea samples from China, Japan or India among others, have been prepared according to the manufacturer instructions and assayed for total polyphenols content using the Folin-Ciocalteu phenol reagent. In addition, the antioxidant activity was assessed by the CUPRAC method and the free-radical scavenging activity was determined using the antioxidant-promoting decay of the stable free-radical DPPH. Caffeine and the most important catechins were identified using RP-HPLC previously validated method. Results from this study suggest that teas, even though they content similar amounts of caffeine, differ considerably in polyphenolic content and therefore in antioxidant and free-radical scavenging activities, depending on the part of the plant used and the process applied to the material for the preparation of the final tea presentation. Correlations among Folin-Ciocalteau’s reactivity of tea samples, the neocuproine reactivity, the DPPH decolourization and the HPLC analysis suggest that the antioxidant activity is due essentially to polyphenolic compounds present in teas, mainly EGCG. The best extraction method of tea powder was the one indicated by dealers. In general, the richest samples belong to green teas and the poorest samples belong to the black teas.Extracts of 40 green, black or oolong high quality tea samples from China, Japan or India among others, have been prepared according to the manufacturer instructions and assayed for total polyphenols content using the Folin-Ciocalteu phenol reagent. In addition, the antioxidant activity was assessed by the CUPRAC method and the free-radical scavenging activity was determined using the antioxidant-promoting decay of the stable free-radical DPPH. Caffeine and the most important catechins were identified using RP-HPLC previously validated method. Results from this study suggest that teas, even though they content similar amounts of caffeine, differ considerably in polyphenolic content and therefore in antioxidant and free-radical scavenging activities, depending on the part of the plant used and the process applied to the material for the preparation of the final tea presentation. Correlations among Folin-Ciocalteau’s reactivity of tea samples, the neocuproine reactivity, the DPPH decolourization and the HPLC analysis suggest that the antioxidant activity is due essentially to polyphenolic compounds present in teas, mainly EGCG. The best extraction method of tea powder was the one indicated by dealers. In general, the richest samples belong to green teas and the poorest samples belong to the black teas.

关 键 词：TEA POLYPHENOLS ANTIOXIDANTS FREE-RADICAL SCAVENGING 

分 类 号：R73[医药卫生—肿瘤]