蓝靛果微波泡沫干燥过程中维生素C降解过程模拟

Simulation of Vitamin C Degradation during Microwave Assisted Foam-mat Drying Process

受干燥条件影响,食品原料中营养成分常发生降解,为阐明微波泡沫干燥条件对蓝靛果中维生素C稳定性的作用规律,本研究在对各影响因素进行通径分析的基础上,分阶段建立维生素C降解动力学模型,并据此建立多物理场仿真模型。结果表明:干燥过程中物料温度和含水率对维生素C降解同时存在直接影响和间接影响,温度升高和含水率下降均会导致维生素C降解量增加,其直接通径系数分别为-0.113和0.715。根据降解动力学方程可得,预热干燥阶段维生素C的降解活化能为3.926 kJ/mol,起泡干燥阶段维生素C的降解反应热为-0.515 kJ/kg,干燥后期是维生素C降解的主要阶段,应控制干燥条件缩短此阶段持续时间。多物理场仿真模型的实测值与模拟值偏差为4.36%,说明所建模型能较好地反映蓝靛果中维生素C在不同干燥阶段的分布和降解规律,由模拟结果可以直接观察到边缘处维生素C的降解速率始终高于中心区,且二者差值随干燥进行而增加。研究结果可为蓝靛果干制加工和维生素C降解分析提供理论依据。

The bioactive ingredients in berries are prone to degradation under different drying conditions.In order to clarify the effects of microwave assisted foam-mat drying(MFD)conditions on the stability of vitamin C in Lonicera caerulea,the degradation kinetic models of vitamin C were established in different drying stages based on the path analysis results.The temperature and the moisture content of berry pulp had both direct and indirect effects on the stability of vitamin C,and their direct path coefficients were−0.113 and 0.715,respectively.The degradation activation energy of vitamin C in preheating drying stage was 3.926 kJ/mol.The reaction heat of vitamin C in foaming drying stage was−0.515 kJ/kg.The drying conditions should be controlled to shorten the duration of rapid heating drying stage due to the large proportion of vitamin C degradation.The deviation between measured value and simulated value of the multi-physics simulation model was 4.36%,indicating that the model can be used to describe and predict the degradation rules of vitamin C under different drying stages.It could be directly observed from the simulation results that the degradation rate of vitamin C at the edge was always higher than the central area,and the difference between the two areas increased with drying progresses.The results of this study provided theoretical basis for the drying of Lonicera caerulea and the analysis of vitamin C degradation.