余甘子微波-热风分段联合干燥工艺优化及动力学模型研究

Study on process optimization and kinetic model of microwave-hot air combined drying for Phyllanthus emblica L.

余甘子在工业生产中的干燥方式主要采用热风干燥,存在干燥效率低,产品质量不佳等问题。为改善此现状,该研究利用微波干燥技术的优势,探究微波-热风分段联合干燥技术在余甘子初加工中的应用,寻求最佳干燥工艺。在不同微波密度、转换点干基含水率、热风温度条件下进行单因素试验,以余甘子干制品多酚含量、黄酮含量、维生素C保留率和褐变度为评价指标,干燥特性为参考指标,分析余甘子微波-热风联合干燥工艺参数适宜范围,采用Box-Behnken响应面法进行优化。确定余甘子的最佳干燥工艺为:微波密度5.0 W/g,转化点干基含水率为2.0 g/g,热风温度为60℃。Two-term模型为描述微波-热风分段联合干燥的最优模型,能较好地模拟最佳工艺条件下干基含水率的变化规律。与传统热风干燥相比,使用微波-热风分段联合干燥工艺干燥余甘子获得的干制品品质更佳,能耗更低,因此微波-热风分段联合干燥技术是一种有效且适合余甘子的干燥方法。

Phyllanthus emblica L.(PE) mainly uses hot air drying in industrial production,but the drying efficiency is low,and the product quality is poor.In this study,the advantages of microwave drying technology were used to explore the application of microwave-hot air combined drying technology in the primary processing of PE,and the best drying technology was sought.Single-factor experiments were carried out under the conditions of different microwave density,dry water content and hot air temperature.The polyphenols content,flavonoid content,vitamin C retention rate,and browning degree of dried PE were taken as evaluation indexes and drying characteristics as reference indexes.The suitable range of drying parameters of dried PE was analyzed,and the optimum drying process was determined by the Box-Behnken response surface method.The processing parameters of microwave-hot air combined drying was 5.0 W/g,the dry base water content at the conversion point was 2.0 g/g,and the hot air temperature was 60 ℃.The two-term model was the optimal model to describe the combined microwave-hot air section drying,which can better simulate the variation law of moisture content of the dry base under the optimal process conditions.Compared with traditional hot air drying,the quality of dried products obtained by microwave-hot air drying was better,and the energy consumption was lower,so microwave-hot air drying technology is an effective and suitable drying method for PE.