Effect of Storage Time on Functional Ingredient and Antioxidant Activity of Ya’an Tibetan Tea

In order to explore the effect of storage time on the tea pigment, polyphenols and antioxidant activity in Ya'an Tibetan tea, the tea pigment, total phenolic content, total flavonoids content and antioxidant activities (ABTS free radical scavenging capacity and DPPH free radical scavenging capacity) in Ya'an Tibetan tea at different storage time were compared. The results showed that the content of theabrownin (TBs) in Tibetan tea was significantly improved from 5.95 g/100 g to 8.54 g/100 g (P<0.05) with the increasing of storage time from four years to ten years, while the content of theaflavin (TFs), thearubigin (TRs), total phenolic content, total flavonoids content, caffeine, catechin and catechin monomeric ((−)-epigallocatechin (EGC), catechin gallate (CG), (−)-Epicatechin gallate (ECG), Epigallocatechin gallate (EGCG), L-Epicatechin (EC)) decreased significantly (P<0.05). Apart from this, ABTS free radical scavenging capacity significantly reduced from 6759.54 µg/g to 4086.43 µg/g (P<0.05), and DPPH free radical scavenging capacity also significantly reduced from 43.50 µg/g to 21.02 µg/g (P<0.05) in Ya'an Tibetan tea, and they were significantly (P<0.05) positively correlated with total phenolic content, total flavonoids content, catechin, caffeine, EGC, EC, EGCG, ECG, TBs, TFs and TRs. However, TBs was negatively correlated with total phenolic content, total flavonoids content, catechin, caffeine, CG, EGC, EC, EGCG, ECG, TFs and TRs (P <0.05). Considering comprehensively, when the storage time is longer, the content of TBs is higher while the content of polyphenols is lower, which makes the aging Tibetan tea also have good health care effect.