不同品种枣果实发育过程中多酚类物质、VC含量的变化及其抗氧化活性

Changes in Phenolics, Vitamin C and Antioxidant Capacity during Development of Different Cultivars of Jujube Fruits

为探索不同品种枣果发育过程中多酚类物质与抗氧化活性的动态变化规律,对灰枣、鸡心枣、梨枣、赞皇枣、磨盘枣、葫芦枣6个枣品种的不同发育期果实中多酚类物质的含量及组成和VC含量及抗氧化活性进行分析测定。结果表明,供试各品种枣果实中总酚、总黄酮、VC含量和抗氧化活性均在采摘初期(幼果期)为最高,其后随着果实的发育呈逐渐下降趋势。其中总酚、总黄酮含量在绿熟期前下降迅速,绿熟期以后变化趋缓,果实接近成熟时则趋于平稳,全红期果实可较采摘初期降低60%以上;VC含量和抗氧化活性在白熟期前下降较快,白熟期后降幅变小。高效液相色谱(high performance liquid chromatography,HPLC)分析结果显示,儿茶素、表儿茶素、芦丁是供试各品种枣果实中最主要的酚类物质,这些酚类物质含量在枣果实发育过程中也呈下降趋势,但在不同品种间存在较大差异。供试枣果实抗氧化活性与其中的总酚、总黄酮、VC以及儿茶素、表儿茶素、芦丁等主要酚类物质的含量均存在极显著相关关系(P<0.01),其中尤以芦丁、表儿茶素、儿茶素与抗氧化活性的相关性较高,说明芦丁、表儿茶素、儿茶素等多酚类物质是枣果中最主要的抗氧化活性成分。磨盘枣、葫芦枣具有较高的多酚类物质含量和抗氧化活性,鸡心枣具有较高的VC含量,是功能性枣果及其加工制品生产的理想品种。

In order to discover the dynamic changes of phenolic compounds and antioxidant capacity during fruit development of different jujube cultivars, the contents of total phenolics, flavanoids, vitamin C and individual phenolic compounds as well as antioxidant capacity of jujube fruits from six cultivars such as Huizao, Jixinzao, Lizao, Zanhuangzao, Mopanzao, and Huluzao, were determined at the stages of young fruit, green maturity, white maturity, half-red maturity, and red maturity. Results showed that the contents of total pefinolics, flavanoids, vitamin C and antioxidant capacity of all tested cultivars of jujube fruits were the highest at young fruit period and decreased during fruit development. The contents of total phenolics and flavanoids decreased rapidly before green maturity and then declined slowly. Above 60% of the declines in total phenolics and flavanoids contents were found in mature jujube fruit as compared with the young fruit. However, the content of vitamin C and antioxidant capacity decreased rapidly before white maturity and thereafter declined slowly. Catechin, epcatechin and lutin were the major phenolic compounds in the tested jujube fruits as analyzed by high performance liquid chromatography. They also showed descending trends with development of jujube fruits. But there was a significant difference among the cultivars tested. Correlation analysis between the contents of total phenolics, flavanoids, catechin, epicatechin, lufin and vitamin C and antioxidant capacity revealed that there were significantly positive correlations between the antioxidant capacity and the contents of total phenolics, flavanoids, catechin, epicatechin, lntin and vitamin C. High correlation coefficients were obtained between antioxidant capacity and the contents of catechin, epicatechin, and lutin, indicating that they are the major determinants of antioxidant capacity in jujube fruit. Furthermore, high content of phenolic compounds and strong antioxidant capacity were found in fruits of the cultivars Mopanzao and Huluzao, while the fruit of Jixinzao contains higher content of vitamin C. Thus, they are the promising varieties for production of functional jujube fi＇uits or processed products with health benefits.