苹果片热风薄层干燥过程中颜色变化的动力学模型

为了研究苹果片在热风薄层干燥过程中的颜色变化规律,分别在60、70、80、90、100℃下对苹果片进行热风薄层干燥处理,以亮度值(L*)、红绿值(a*)、黄蓝值(b*)、总色差(ΔE)、饱和度、褐变指数(BI)等为指标描述苹果片的颜色变化,并分别应用零级和一级反应动力学方程进行数学模型的拟合分析。结果表明,热风薄层干燥过程中,苹果片的L*值随着干燥时间的延长而逐渐降低,而a*值、b*值、ΔE、饱和度、BI值则逐渐升高,且反应速率常数k随着干燥温度的升高而呈现出一定的规律性变化。根据拟合决定系数R2的比较结果,零级反应动力学模型能更好的描述和预测苹果片在热风薄层干燥过程中的L*、a*、b*、ΔE值变化,而饱和度和BI值的变化则更符合一级反应动力学模型。该模型可以对苹果片在热风薄层干燥中的颜色变化进行预测,为优化干燥工艺提供参考。 

Color change kinetics model of apple slices during hot-air thin drying

This study revealed the color degradation of apple slices in a hot air drying process. The indicators containing brightness values(L*),red and green values(a*),yellow and blue values(b*),total color changes(ΔE),chroma,browning index(BI) had been investigated during the hot air drying process of apple slices at60,70,80,90,100 ℃,respectively. Zero-order and first-order kinetics equation had been applied to fit mathematical model. The results showed that the L* of the apple slices with the extension of the drying time gradually reduced,while a*,b*,ΔE,chroma,BI value was gradually increased,and the reaction rate constants(k) values of these parameters as the color of drying temperature rose showed a certain regularity changes.According to the results compared with regression coefficient R2 fit,zero-order kinetics model could better describe and predict the L*,a*,b*,ΔE change of apple slices in the hot air drying process,while the changes of chroma and BI value were more consistent with first-order kinetics model. This model could be for predicting the color change of apple slices during hot-air thin drying,and providing reference for optimization of drying process.