苹果汁中展青霉素的紫外降解效果及动力学研究

UV Degradation and Kinetics of Patulin in Apple Juice

为研究苹果汁中展青霉素(PAT)经紫外照射后的降解效果,本试验以添加PAT标准品的市售苹果汁为研究对象,考察紫外照射强度、PAT初始浓度、液层厚度、温度对苹果汁PAT降解效果的影响,并对其降解曲线和降解方程进行拟合,同时对比分析紫外处理前后苹果汁pH值、可溶性固形物含量、可滴定酸含量和抗坏血酸含量的变化。结果表明,紫外照射处理可有效降低苹果汁中PAT含量,且降解过程符合一级动力学方程;紫外照射强度越大、PAT初始浓度越低、液层厚度越小,苹果中PAT降解速率越快,即温度对PAT降解速率的影响较小。建立紫外照射强度、PAT初始浓度、液层厚度3种影响因素的光解速率常数,回归方程(y=-0.143-0.087x_1+0.014x_2+0.011x_3)模型拟合度R^2=0.988,回归方程显著。此外,紫外照射处理对苹果汁pH值、可溶性固形物含量、可滴定酸含量和抗坏血酸含量影响不大。本研究结果为紫外降解苹果汁中PAT提供了理论基础和技术指导。

Parameters affecting the UV degradation process of added patulin（PAT） in apple juice were analyzed through single factor experiments UV light intensity, initial PAT concentration, layer thickness, UV reaction time, and temperature were considered. The degradation rate and equation of PAT was fitted into a kinetic model. The physical and chemical properties of apple juice, including pH value, soluble solids contents, titratable acid and ascorbic acid were investigated. The results showed that UV treatment could effectively reduce the content of PAT in apple juice, and the photodegradation of PAT followed first-order kinetics. The apparent degradation rate constant（k） increases with the higher UV irradiation intensity, the decreasing initial concentration of PAT and the smaller the liquid layer thickness, while the temperature had no significant effect. The photolysis rate equation y=-0.104-0.131 x1＋0.014 x2＋0.011 x3 was established with on the three key degradation factors of UV light intensity, initial PAT concentration, layer thickness. The fitting degree R^2=0.988 means the model was significant. In addition, there were minor changes on the pH value, soluble solids contents, titratable acid and ascorbic acid of apple juice after UV degradation. The results of this study provide a theoretical basis and technical guidance for UV degradation of PAT in apple juice.