Changes of Active Constituents and Their Relationship with Antioxidant Capacity in Peel and Pulp of ‘Dongzao＇ Jujube during Storage | 冬枣冷藏期间果皮和果肉抗氧化物质含量及其抗氧化活性的变化

Chinese. 以白熟期冬枣为试材,对其冷藏期间果皮和果肉抗氧化物质含量及其体外抗氧化活性的变化进行测定,并采用HPLC-MS定性定量检测果皮中4种形态酚（游离酚、酯化酚、苷化酚和结合酚）含量的变化,分析果皮和果肉抗氧化物质含量与其抗氧化能力的关系及其主要形态酚酸的抗氧化能力。结果表明：随着贮藏期的延长,果肉的总酚、类黄酮和抗坏血酸的含量及其抗氧化能力均先升后降;而果皮中总酚、类黄酮和抗坏血酸含量及其抗氧化能力则持续下降;贮藏期间果皮中总酚、类黄酮和花青素含量始终极显著高于果肉（P〈0.01）。相关分析表明：果皮中除花青素外的活性成分与体外抗氧化活性均显著相关,其抗氧化能力也极显著高于果肉（P〈0.01）。贮藏期间,果皮中游离酚主要含有儿茶素、表儿茶素和芦丁,它们的含量变化呈先增加后降低趋势,且极显著高于其他3种形态酚,酯化酚和苷化酚含量较低,结合酚中以香豆酸含量略高,总酚中游离酚是主要的抗氧化活性物质。

English. Postharvest white-mature Dongzao jujube （Ziziphus jujube ‘ Dongzao＇ ） was stored at 0 ℃ , and the variations in contents of active components in peel and pulp and the antioxidant capacities were investigated. Additionally, free, esterified, glycosided, and insoluble-bound forms of phenolic acids in the peel were separated and quantified by the high performance liquid chromatography with mass spectrometry （HPLC-MS）. Moreover, the antioxidant abilities of main form of the phenolic acids were evaluated, and the relationship between the content and antioxidant capacities of active constituents in the peel and pulp were analyzed. The results showed that the concentration and antioxidant activities of total phenolics, flavonoids, and ascorbic acid decreased and then increased in the pulp, while they exhibited a continuously declined trend in the peel during storage The total content of phenolics,flavonoids and anthocyanin in peel was more than that in pulp （P 〈0.0! ）. The antioxidant abilities of the active compounds except of anthocyanin in peel was significantly higher than that in pulp（P 〈 0. 01 ）. The free phenolic acids in peel were mainly catechin, eicatechin and rutin. Their content firstly increased and then decreased during storage and were significantly higher than that of other three phenolic acids. The contents of phenolic acids in esterified and glycosided forms were more than that of insoluble- bound form. The p-coumaric acid was presented mainly in insoluble-bound forms. The results indicated that free phenolic acids were the main part of the antioxidant compounds.