Influencing factors on property of browning substrate (-)-epicatechin from litchi pericarp tissues
SUN Jian1,2,3,JIANG Yue-ming2,PENG Hong-xiang3,LI Yue-biao2,DUAN Xue-wu2,YANG Bao2,YOU Yan-li2,SONG Li-li2,CHENG Gui-ping2 (1Agro-Processing Research Institute,Guangxi Academy of Agricultural Sciences,Nanning,Guangxi 530007 China; 2South China Botanical Garden,Chinese Academy of Sciences,Guangzhou,Guangdong 510650 China; 3Horticultural Research Institute,Guangxi Academy of Agri-cultural Sciences,Nanning,Guangxi 530007 China)
The effects of illumination,temperature,pH value,gaseous component,oxidant,reductant and metal ion on stabili-ty of browning substrate (-)-epicatechin from litchi pericarps were analyzed in the present study. The results showed that (-)-epicatechin was unstable and easy to turn brown under illumination,high temperature and alkaline environment. The O2 treatment accelerated the enzymatic browning reaction between substrate and PPO,while the CO2 treatment reduced this reaction. Oxidant H2O2 accelerated but reductant Vc or Na2S2O5 prevented the browning reaction. In addition,K+,Na+,Ca2+ and Zn2+ had no obvious effect on stability of (-)-epicatechin solution,but the substrate solution was unstable after the addition of Fe3+,Fe2+,Cu2+ or Pb2+. Application of appropriate treatment could delay the pericarp browning,extend the shelf life and increase the commercial value of litchi fruit.