Antioxidant Activity and Stability of Anthocyanins from Zijuan Tea

Objective:To study the antioxidant activity and stability of anthocyanins from Zijuan tea. Methods:The antioxidant activity was estimated by the FRAP, ABTS and DPPH assays, and the effect of preservation condition on the stability was evaluated. Results:The anthocyanin concentration was 0.39 μg/mL when the FRAP of anthocyanins from Zijuan tea was 0.5 mmol/L, and the IC₅₀ of ABTS⁺·scavenging capacity and DPPH·scavenging capacity of anthocyanins were 0.76 and 0.13 μg/mL, respectively.The total antioxidant capacity, ABTS⁺·scavenging capacity and DPPH·scavenging capacity of anthocyanins were positively correlated with anthocyanins concentration in the range of test concentration, and were stronger than those of V_C, respectively. The pH value had significant affects on the color and absorption spectra of anthocyanins solution, and the anthocyanins were relatively stable when pH ≤ 6.0. With the increasing of temperature and storing time prolonged, the preservation rate of anthocyanins from Zijuan tea gradually decreased (p<0.05). The light, oxidant, reductantand metal ions (Fe³⁺, Cu²⁺, Mg²⁺, Ca²⁺, Al³⁺) also significantly affected the stability of anthocyanins (p<0.05), and the longer light time, the higher the concentration of H₂O₂ and Na₂SO₃ and the longer storing time, the lower the preservation rate of anthocyanins.Conclusions:The anthocyanins from Zijuan tea had strong antioxidant activity, but their stability were relatively poor. They should be stored under low-temperature and acid environment without light, away from oxidant, reductant and Fe³⁺, Cu²⁺, Mg²⁺ and metal ion and so on.