مقايسه اپي كاتشين در طي مراحل فرآوري چاي سياه و سبز ايراني Thea sinensis

Comparison of Epicatechin during Processing Stages of Iranian Black and Green Tea

Plants produce thousands of phenolic and polyphenolic compounds as secondary metabolites. They are essential to the physiology of plants. However, the most researches to date on possible health benefits of polyphenols have focused on the flavonoids. The widespread distribution of flavonoids, their variety and their relatively low toxicity compared to other active plant compounds mean that humans use significant quantities in their diet. Flavonoids show anti-allergic, anti¬inflammatory, anti-microbial and anti-cancer activities. The beneficial effects of fruits, vegetables, and tea have been attributed to flavonoid compounds. Flavan-3-ols is a type of flavonoids and one of which is catechin compounds. Catechins exsist in white tea, green tea, black tea, grapes, cocoa, lentils and black-eyed peas. Tea with scientific name Thea sinensis is used in various forms, i. e., green tea, brown tea, brick tea, black tea and white tea. In Iran black tea is especially consumed. The fresh leaves are packed after processing stages including withering, rolling, fermentation and drying. This research was made to compare epicatechin (a kind of catechins) during the processing stages of Iranian black and green tea. The tea samples were extracted and analyzed by HPLC, using epicatechin standard. Then, comparing the created curve with standard curve, epcatechin in green tea leaves was calculated. The amount of this stuff was measured according to mg/kg of dry weight at each stage. The amount of epicatechin in fresh green leaf was 775, withering step 690, rolling step 606 and fermentation step 540 mg/kg of dry weight. The results of ANOVA showed that epicatechin concentration in the green tea was significantly high, whereas p>0.01 among different tea processing stages in Iran, Also means comparison showed that there is a significant difference between stages of fresh, withering, rolling and fermentation so that this matter excessively exists in fresh leaf and the least amount of this matter can be found in fermentation stage.