Differences in Antioxidant Components and Activity of Pear Jujube (Zizyphus jujube Mill. cv. Lizao) Leaf Tea among Different Growth Stages

Objective: To investigate the changing patterns of antioxidant components and activity of pear jujube(Zizyphus jujube Mill.cv.Lizao) leaf tea during different growth stages.Methods: The tender leaves of pear jujube trees were selected in five growth stages from May to August followed by pan-firing to produce the tea,and the contents of total phenols,total flavonoids and vitamin C,phenolic compositions,and antioxidant properties including the capability to scavenge DPPH and ABTS free radicals and reducing power were investigated.Results: Antioxidant components and activity of pear jujube leaf tea in July and August were better than in May and June.The contents of total phenols,total flavonoids and vitamin C significantly varied among the different stages(P 0.05),from(29.94 ± 0.28) to(42.65 ± 0.56) mg galic acid eq./g FW(fresh weight),from(16.61 ± 0.39) to(25.21 ± 1.53) mg rutin eq./g FW and from 136.5 to 324.6 mg/100 g,respectively.Gallic acid,catechin,rutin and quercetin were detected as major phenolics,and their contents had significant differences among different stages(P 0.05);rutin was the most abundant among these phenolics,reaching maximum content of 60.11 mg/100 g.Oxidation resistance were significantly correlated with total phenols(P 0.05) and total flavonoids(P 0.01),but not correlated with vitamin C content.Conclusion: The antioxidant performance of pear jujube leaf tea harvested in summer is better than that in spring,and rutin is the most dominant component of phenolic compounds.