Study On Technology Of Microwave Assisted Foam-Mat Drying Of Blue Honeysuckle

Blue honeysuckles (Lonicera edulis Turcz) have significant edibleness and health benefits due to their rich nutrient. The microwave assisted foam-mat drying method has superiority in nutrition inventory, production rate and conservation of energy, compared to the conventional drying method such as spray drying method, freeze drying method and heated-air drying method. It is important to understand the microwave assisted foam-mat drying mechanism and mass and heat transfer process for fruits and vegetables.A single-factor experimental design was employed to study the microwave assisted foam-mat drying characteristics of blue honeysuckle. The results show that the moisture content had significantly negative correlation with the microwave power. The anthocyanin contents and vitamin C contents of blue honeysuckle were dropped rapidly with microwave power. High loading mass increases the moisture ratio and decrease the content of anthocyanin and vitamin C due to the prolonging drying time. The thickness has the least effect on the objective indexes of final dried product.The effect of process parameters, in terms of microwave power, loading mass and thickness, on the quality index including final moisture ratio, anthocyanin content, vitamin C content and color value by using responding surface methodology(RSM). The following conclusions were obtained:1) The most important factor on final moisture ratio was microwave power. Moisture ratio was reduced with the rise of microwave power. When the thickness was8mm, the moisture ratio was lower. Moisture ratio was negative correlation with microwave power.2) The most important factor on anthocyanin content was thickness. Anthocyanin content had negative relationships with drying time. As a result, the rise of loading mass and thickness will decrease the anthocyanin content.3) The most important factor on vitamin C content was microwave power. The content of vitamin C was negative correlation with both loading mass and thickness. The content of vitamin C increased up to certain level and then dropped with microwave power increase.4) The most important factor on color value was microwave power. The drying times also has significant effect on color value of honeysuckle powder.The optimum processing parameters and response values were developed, in the conditions of10kW of microwave power,200g of loading mass and5.5mm of thickness. The final moisture content of blue honeysuckle powder was9.4832%, the anthocyanin content was56.398mg/g, the vitamin C content was14.7735mg/g and the color value was10.396. And the coefficient between experimental results and theoretical prediction is0.991.In order to study the process of water diffusion and the absorption of microwave power during microwave assisted foam mat drying, appropriate models were obtained based on conservation of energy, heat balance and the diffusion equation. The relationship between pulp thermo-physical properties and microwave power was obtained. According to the similarity theory, the experimental model may be expanded to large-scale microwave equipment and verification test.