干制加工对龙眼果肉多酚组成及抗氧化活性的影响

研究了龙眼果肉干制过程中肉干燥前后总酚的含量、存在形式及单体酚的组成和其抗氧化能力差异.结果表明,龙眼果肉经干燥后游离酚含量及其FRAP抗氧化活性和DPPH抗氧化活性均显著下降(P＜0.05)；结合酚含量及其FRAP抗氧化值显著上升(P＜0.05),但其DPPH抗氧化值变化不明显(P＞0.05).经过干燥后,龙眼游离酚...

EFFECT OF DRYING ON PHENOLIC PROFILES AND ANTIONXIDANT ACTIVITY OF LONGAN PULP

In order to investigate the composition of phenolics and the changes of their antioxidant activity during the longan drying, the content and the existing form of total phenolics , the monomer composition and the antioxidant activity before and after drying were analyzed. The results showed that the content of the free phenolics，FRAP antioxidant activity and DPPH antioxidant activity of the free phenolics were significantly decreased after the drying process（P 0.05）. while, the content of bound phenolics and FRAP antioxidant activity of the bound phenolics were significantly increased（P 0.05）. Nevertheless, no significant differences（P 0.05）were shown for the DPPH antioxidant activity of the bound phenolics .Meanwhile, the contents of monomer phenolics of epicatechin and tetramethyl catechol which were the composition of free phenolics were significantly decreased. However, the contents of gallic acid,vanillic acid,coumarate and quercetin were significantly increased（P 0.05）.Compare to the bound phenolics,the contents of syringic acid,tetramethyl catechol, vanillic acid and epicatechin were significantly increased（P 0.05）. These results indicated that the drying process had different impacts on the composition and content of phenolics of longan pulm, and also influence the their biological activity .