EXPERIMENTAL STUDIES OF FOOD SYSTEMS EVAPORATION IN A MICROWAVE FIELD

The objective of the study is to experimentally investigate the kinetics and energetics of the proposed evaporation technology using targeted energy delivery to polar molecules using microwave electromagnetic energy sources in an innovative evaporation unit. Kinetic relationships were established for the influence of microwave electromagnetic power, pressure, concentration, and product type on moisture removal and the rate of vaporization. Dynamic parameters for regulating the microwave electromagnetic power were determined. The design of the proposed vacuum evaporator with electromagnetic energy sources was substantiated, yielding a final product with a dry matter concentration of 90 %. Experimental studies were conducted on apple juice. The parameters influencing the unit's vapor productivity were the influence of pressure, specific electromagnetic field (EMF) power, and product type. Based on the experimental results, relationships were obtained indicating that the evaporation rate remained constant throughout the process, up to a final product concentration of 80–90 %. The process temperature is 35–40 °C, which reduces the thermal impact on the drying object (product). This positively impacts the quality and value of the finished product, as it preserves its biologically active and heat-sensitive components, including vitamins, which is impossible to achieve at high process temperatures. The obtained data indicate that during the evaporation of food systems, it is possible to transition from boundary conditions of the third kind to conditions of the second kind using the principle of targeted energy delivery to the polar molecules of the raw material using a microwave field. Based on the experimental data, a criteria model is proposed for accurately calculating the steam capacity of a microwave vacuum evaporator. The product obtained using the proposed technology has a good appearance and consistency, is free of foreign odor, and is not burnt, which is observed in traditional evaporators. This leads to an increased shelf life and high quality of the finished product.