热泵干燥过程荔枝果肉多酚组成及抗氧化活性变化

Changes in Phenolic Compounds and Antioxidant Activities in Litchi Pulp during Heat Pump Drying Process

以荔枝鲜果为原料,分析高温热泵干燥过程中荔枝果肉多酚的组成及抗氧化性活性变化。对干制过程中荔枝进行取样测定果肉总酚的质量分数、存在形式及酚类化合物组成和其抗氧化能力。结果表明:荔枝经干制后果肉中游离酚、结合酚和总酚质量分数显著降低(P<0.01);游离酚、结合酚和总酚的ORAC抗氧化值显著降低(P<0.01),其中游离酚对抗氧化能力的贡献最大;抗氧化能力和酚质量分数的多少呈显著正相关,酚质量分数越高,抗氧化能力越强。经干制后,荔枝果肉游离酚组成中没食子酸、香草酸、咖啡酸、表儿茶素和芦丁质量分数显著上升(P<0.05);儿茶素显著下降(P<0.05);四甲基邻苯二酚质量分数持续下降,干制成品中未检测到;结合酚中没食子酸、儿茶素、咖啡酸和表儿茶素质量分数显著上升(P<0.05);芦丁质量分数显著下降。

In order to research the changes of phenolic compounds and antioxidant activites of l itchi fruit during high temperature heat pump drying（HTHPD） processing,the content,composition and antioxidant activities of phenolic c, ompounds of litchi pulp at different period were investigated. Results indicated that the contents of free and bound phenolic conlpounds and its ORAC antioxidant activities significantly decreased after HTHPD processing （P〈0.01）. Free phenolic compounds contributed greatly to total antioxidant activity. There was a direct relationship between tYee and hound phenolics contents and antioxidant activities in phytochemical extracts of litchi pulp. The higher phenolic contents in fruits resulted in higher antioxidant activity. The contents of free phenolic of gallic acid,vanillic acid,caffeic acid, （-）-Epicatechin and rutin significantly increased （P〈0.05）, （＋）-Catechin and tetramethyl catechol significantly decreased （P〈0.05）. While the contents of bound phenolic of gallic acid, （＋）-Catechin,caffeic acid and （-）-Epicatechinsignificantly increased （P〈0.05）, rutin significantly decreased （P〈0.05）.