杨梅澄清汁及浓缩汁中花色苷热降解动力学的研究

杨梅花色苷易受温度、pH值等因素的影响而发生降解，是导致产品外观品质变劣的主要原因。本文研究了杨梅澄清汁及浓缩汁内花色苷在不同pH值和不同加热温度下的热稳定性。花色苷降解动力学数据的分析结果表明：杨梅花色苷热降解属动力学一级反应，随着pH值和温度的升高，杨梅花色苷降解的半衰期(t_1/2)和热降解活化能(Ea)显著下降，即花色苷的降解速度增大；同一处理条件下，浓缩果汁的t_1/2明显低于澄清汁。而反应速率常数k和Ea值大于澄清果汁，说明澄清汁花色苷的热稳定性优于浓缩汁。

Thermal degradation kinetics of anthocyanins in Myrica rubra juice and concentrate

Thermal stability of anthocyanins in Myrica rubra juice is susceptible for degradation by factors like temperature and pH values. The degradation of anthocyanins led to the change of color, and the product quality is therefore influenced. This paper studied the thermal stability of Myrica rubra juice and concentrate under different temperatures and pH values. Results of kinetic study of the degradation process of anthocyanins in Myrica rubra juice suggeste that the degradation process is a first order degradation kinetic process. As the increase of temperature and pH value, the half-life degradation of anthocyanins and activation energy for the thermal degradation decrease significantly. Under the same condition, the half-life of concentrate is significantly lower than that of the juice. And the k and Ea values of concentrate are higher than that of the juice. The result indicate that anthocyanins are more stable in juice than in concentrate.