tailieunhanh - Báo cáo nghiên cứu khoa học: " TOTAL POLYPHENOLS, TOTAL CATECHINS CONTENT AND DPPH FREE RADICAL SCAVENGER ACTIVITY OF SEVERAL TYPES OF VIETNAM COMMERCIAL GREEN TEA"

ScienThirty types of commercial Vietnamese-brand teas (21 green teas, 5 black teas, 4 oolong teas) in Ho Chi Minh city were investigated for total polyphenols content (TPCacid gallic equivalent), total catechins content (TCC-catechin equivalent) and DPPH (2,2diphenyl-1-picrylhydrazyl) free radical scavenger activity (RSA - Vitamine C equivalent). | Science Technology Development Vol 10 - 2007 TOTAL POLYPHENOLS TOTAL CATECHINS CONTENT AND DPPH FREE RADICAL SCAVENGER ACTIVITY OF SEVERAL TYPES OF VIETNAM COMMERCIAL GREEN TEA Pham Thanh Quan 1 Tong Van Hang 2 Nguyen Hai Ha 1 Bach Long Giang 1 1 University of Technology VNU-HCM 2 vnu-hcM Manuscript Received on August 02f 2006 Manuscript Revised September18th 2007 ABSTRACT Thirty types of commercial Vietnamese-brand teas 21 green teas 5 black teas 4 oolong teas in Ho Chi Minh city were investigated for total polyphenols content TPC-acid gallic equivalent total catechins content TCC-catechin equivalent and DP PH 2 2-diphenyl-1-picrylhydrazyl free radical scavenger activity RSA - Vitamine C equivalent . It was found that green tea had the highest TPC ppm TCC ppm and RSA 288 23 mg in three grams dried tea higher than those of oolong tea whereas black tea had the lowest TPC TCC RSA. However high inconsistency and high deviation from mean values were observed within green tea group. Unexpectedly several green tea types had low TPC TCC and RAC even as low as those of black tea. This evidence demonstrated the instability and unevenness of green tea quality in Vietnam market. Key words Green tea DP PH radical scavenger activity total polyphenols content total catechins content. 1. INTRODUCTION Tea has been one of the most consumed beverages in all over the world. Tea is used not only as fresh drink but also as traditional herb which has many benefits for human health. Tea has been believed and recently proven in several scientific articles about its abilities such as anticancer anti tumor anti-aged. Moreover tea is able to help relieve blood pressure reduce heart attack rate. 6 11 13 14 . This is primary because of the affect of polyphenols tea main components which could be as high as 30 - 35 in dried weight of fresh tea shoots 2 3 . Tea polyphenols consist of several types of catechins compounds usually 5 or 6 in some tea breeds the number of .