Change of Main Components and Physiological Functions of Post-fermented Green Tea with Reduced Caffeine

We developed a post-fermented tea that contains reduced caffeine and exhibits positive functions to maintain our health. We also analysed the main components and physiological function of the post-fermented tea compared to green tea as the control. The tea leaves with reduced caffeine were fermented with lactic acid bacteria (Lactobacillus plantarum) for four weeks. HPLC was employed to analyse the caffeine, catechin and theanine in the infusion of post-fermented tea leaves. The antioxidative activity was analysed spectrophotometrically. The preadipocyte (3T3-L1) differentiation-inhibitory test, which is an index of anti-obesity, was employed. As fermentation progressed, theanine and catechin contents tended to decrease, though caffeine level was unchanged. The infusion of the post-fermented tea exhibited high antioxidative activity during fermentation, while important antioxidant catechin content was decreased. In addition, the preadipocyte differentiation-inhibitory test showed the inhibition effect of the post-fermented tea infusion on adipogenesis in a dose-dependent manner. These results showed that the fermentation did not affect the antioxidant and anti-adipogenesis activities. Fermentation denatured the structure of leaf tissue, and some novel molecules might have been produced, exhibiting positive effects. These results showed that the post-fermented tea we developed was a unique tea product showing antioxidative activity and adipogenesis inhibitory effect and may prove to be a functional food for our health.