多酚氧化酶的射频加热灭活效果及动力学分析

为了阐述多酚氧化酶(PPO)射频加热对灭活规律,本文研究了板间距和溶酶磷酸盐缓冲液电导率对加热速度及酶灭活效果的影响,进行了酶灭活动力学模型研究。结果表明:极板间距和电导率影响射频加热速度,极板间距越大升温越慢,电导率为0.1 S/m时,升温速度最快。在极板间距120 mm,电导率0.1 S/m时,射频加热105 s,PPO的灭活率为91.88%。对酶灭活的动力学曲线分别用一级动力学模型、Weibull模型和Log-Logistic模型进行拟合。通过对模型的拟合评价参数即精确因子Af、偏差因子Bf、根平均方差RMSE和决定系数R2进行比较,PPO的灭活动力学曲线不符合一级反应动力学模型,Weibull和Log-Logistic模型都能较好的拟合PPO失活曲线。通过衡量三种模型的预测值和实测值的一致性,Log-Logistic模型能最好地拟合射频加热条件下多酚氧化酶的失活曲线。

Inactivation Effect of Radio Frequency Heating on Polyphenol Oxidase and the Analysis of Kinetics

In order to investigate the pattern of polyphenol oxidase (PPO) inactivation by radio frequency (RF) heating, the effects of the electrode gap and the electrical conductivity of phosphate-buffered saline (PBS) on the heating rate and inactivation of PPO were studied, and the data were fitted to different models to determine the inactivation kinetics. The results showed that both the electrode gap and conductivity affected the RF heating rate. The larger the electrode gap was, the slower was the rate of temperature increase. When the electrical conductivity was 0.1 S/m, the rate of temperature increase was the fastest. At the electrode gap of 120 mm, conductivity of 0.1 S/m, and RF heating duration of 105 s, the PPO inactivation rate was 91.88%. The first-order kinetics model, Weibull model, and log-logistic model were used to fit the inactivation curve of PPO. The fitness of the three models was evaluated by using a series of indices, including the accuracy factor (Af), bias factor (Bf), root mean square error (RMSE), and correlation coefficient (R2). The curve did not show compliance with first-order kinetics, whereas both the Weibull and log-logistic models could fit the inactivation curve well. The consistencies between measured and predicted values of the three models were examined and the log-logistic model provided the best fitness for the PPO inactivation curve under RF heating.