Abstract:

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.

Key words: pear jujube leaf tea, different growth stages, antioxidant capacity, phenolic composition