蓝莓花色苷降解动力学及稳定性

Degradation Kinetics and Stability of of Anthocyanins from Blueberry

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 k J/mol,pH 1.0时活化能最大,为83.73 k J/mol,热降解反应为吸热非自发反应;光照和H_2O_2会加快蓝莓花色苷的降解,花色苷在光照和H_2O_2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H_2O_2体积分数的升高明显增加;此外,质量分数0.20%Na_2SO_3对花色苷的降解起到抑制作用,而质量分数0.05%、0.10%、0.15%Na_2SO_3会促进花色苷降解反应。

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 anthoc yanins under acidicconditions 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 pH6.0,the activation energy(Ea)was the lowest(44.77kJ/mol),while the highest value(83.73kJ/mol)was observed at pH1.0.The thermal degradation reaction was a non-spontaneous endothermic process.Both light and H2O2accelerated the degradation of anthocyanins,and the two degradation processes obeyed a first-order kinetic equation.The degradation rate was0.0148d-1under light condition,and the half-life was47d.The degradation rate increased with the increase of H2O2concentration.In addition,the degradation of anthocyanins was inhibited by0.2%Na2SO3,but promoted by0.05%,0.1%or0.15%Na2SO3.