蓝莓花色苷降解动力学及稳定性

以蓝莓花色苷为原料，采用pH示差法测定了不同pH值、温度、光照强度、氧化剂和还原剂对花色苷稳定 性的影响。结果表明：不同pH值下花色苷热降解符合一级动力学方程，强酸性条件下蓝莓花色苷的热稳定性强于 弱酸和中性；花色苷的热稳定性差，随着温度升高，花色苷的降解速率k明显增大，降解半衰期和递减时间D值明 显减小，pH 6.0时活化能最小，为44.77 kJ/mol，pH 1.0时活化能最大，为83.73 kJ/mol，热降解反应为吸热非自发反 应；光照和H2O2会加快蓝莓花色苷的降解，花色苷在光照和H2O2处理条件下降解均符合一级动力学方程，在光照条 件下的降解速率为0.014 8 d－1，半衰期为47 d，花色苷降解速率随着H2O2体积分数的升高明显增加；此外，质量分 数0.20% Na2SO3对花色苷的降解起到抑制作用，而质量分数0.05%、0.10%、0.15% Na2SO3会促进花色苷降解反应。

Degradation Kinetics and Stability of of Anthocyanins from Blueberry

The effects of pH, temperature, light intensity, oxidant and reducing agent on the stability of anthocyanins from blueberry were determined by pH-differential method. Results showed that the thermal degradation of anthocyanins at different pH values followed a first-order kinetic equation, and the stability of blueberry anthocyanins under acidic conditions was stronger than under weakly acidic and neutral conditions. The anthocyanins were sensitive to temperature as evidenced by a significant increase in the degradation rate (k) as well as a significant decrease in the half-life (t1/2) and the decimal reduction time (D value) with the increase of temperature. At pH 6.0, the activation energy (Ea) was the lowest (44.77 kJ/mol), while the highest value (83.73 kJ/mol) was observed at pH 1.0. The thermal degradation reaction was a non-spontaneous endothermic process. Both light and H2O2 accelerated the degradation of anthocyanins, and the two degradation processes obeyed a first-order kinetic equation. The degradation rate was 0.014 8 d-1 under light condition, and the half-life was 47 d. The degradation rate increased with the increase of H2O2 concentration. In addition, the degradation of anthocyanins was inhibited by 0.2% Na2SO3, but promoted by 0.05%, 0.1% or 0.15% Na2SO3.