Microwave and ultrasound enhancement of convective drying of strawberries: Experimental and modeling efficiency

This article presents the results of convective drying of strawberries enhanced with microwaves and ultrasound acting together or separately. Five drying programs applied for this biological product with different application of microwaves and ultrasounds and pure convective drying as a reference test were carried out. The purpose of the studies was to analyze the effect of hybrid drying with respect to drying kinetics, total energy consumption, and the quality of this dried product. It was proved that convective drying assisted with microwaves and ultrasounds significantly improves the efficiency of heat and mass transfer in strawberries. However, microwave and ultrasound as different energy sources affect the energy consumption and the product quality in different way. The microwaves generate at most the "heating effect" and the ultrasound reveal significantly the "vibration effect". Both these energy sources acting together accelerate the drying rate due to "synergistic effect". The model of drying kinetics used in this article illustrate the mentioned above effects.