辅色剂对紫淮山花色苷稳定性的影响及其热降解动力学研究

为探究谷胱甘肽和没食子酸对紫淮山花色苷的辅色作用,本文研究了谷胱甘肽和没食子酸对紫淮山花色苷降解率、热稳定性及色差的影响。试验表明,谷胱甘肽和没食子酸能有效抑制花色苷的降解,且最佳添加量分别为0.03%和0.2%。在此添加量条件下,紫淮山花色苷在50、70、90℃水浴中的热降解均符合一级降解反应动力学规律。添加谷胱甘肽和没食子酸的紫淮山花色苷降解速率常数(k)小于对照组,半衰期(t 1/2)和活化能(Ea)高于对照组,说明谷胱甘肽和没食子酸能够增强花色苷的热稳定性。色差测定结果表明,经谷胱甘肽和没食子酸辅色后的紫淮山花色苷,其明度指数(L*)和色品指数(a*、b*)较对照组变化缓慢,颜色的稳定性增强。

Effects of Copigments on the Stability of Purple Yam Anthocyanins and Their Thermal Degradation Kinetics

To investigate the copigmentations of glutathione and gallic acid on purple yamanthocyanins,the effects of glutathione and gallic acid on the degradation rate,thermal stability and color difference of anthocyanins were studied.The results showed that glutathione and gallic acid could effectively inhibit the degradation of anthocyanin,and the optimal addition amount was 0.03%and 0.2%,respectively.Under that additive quantity condition,the thermal degradations of purple yam anthocyanin in 50℃,70℃and 90℃water bath were in accordance with the first-order degradation kinetics.Compared with the control group,the degradation rate constant(k)of purple yam anthocyanin decreased after adding glutathione and gallic acid,the half-life and activation energy were improved,which suggests that glutathione and gallic acid can enhance the thermal stability of anthocyanin.Meanwhile,the color difference results indicated that the brightness index(L*)and chromaticity index(a*,b*)of purple yam anthocyanin with the effects of glutathione and gallic acid change slowly,Therefore the color stability is enhanced.