Antioxidant capacity and chemical constituents of Chinese jujube (Ziziphus jujuba Mill.) at different ripening stages

Chinese jujube (Ziziphus jujuba Mill.) is admired for its high nutritional value and has been commonly used in traditional Chinese medicine for its remarkable health functions. The antioxidant capacity (AOC) and the other qualitative parameters of jujube were measured at ripening stages of green maturity (GM), white maturity (WM), halfred maturity (HM), and red maturity (RM). AOC was screened with DPPH radical scavenging activity, Trolox equivalent antioxidant capacity, and reducing power. Jujube showed a significant (p<0.05) increase in the total soluble solids and titratable acidity, and firmness have no change of all maturity stages, while ascorbic acid showed a significant (p<0.05) declining trend. At stage of GM, the total phenolic content (TPC), total flavonoid content (TFC), and AOC in peel were the highest, and then rapidly decreased after WM. Meanwhile TPC and AOC in pulp reached a peak value in WM then declined, but TFC declined slowly during maturity.