INTENSIVE DRYING METHODS FOR APPLE SLICES WITH CONVECTION AND COMBINED ENERGY SUPPLY

Drying is a mass-exchange process of removing moisture from a material by evaporation, which results in an increase in the shelf life of raw materials while reducing transport weight. Apples are a common type of fruit that is present in our diet almost all year round. They contain a significant amount of vitamins (C, B1, B2, P, E), manganese, potassium, and easily digestible iron. Apples are hypoallergenic and can be consumed by almost everyone. The purpose of the work is to intensify the drying of apple slices to low residual moisture without loss of biologically active substances. Research methods. The study of the kinetics of the slices drying process was performed on an experimental convective stand with a system of automatic recording and processing of information at a drying agent temperature of 60, 80, 80/60 ºC and a stepwise combined mode with a combination of IR radiation and convective heating of IR (100 W)+60 °C/60 °C, speed 1.5 m/s, moisture content 10 g/kg dry air. Results and conclusions. Summarising the research results, it can be concluded that the temperature of the drying agent at 80 °C ensures a short duration of the dehydration process, but the organoleptic characteristics of the finished product are unsatisfactory. Drying at a temperature of 60 °C leads to an increase in dehydration time, and as a result, to an increase in energy consumption and a deterioration in organoleptic characteristics and recoverability. It is recommended that the dehydration process of slices be carried out according to the developed stepwise drying modes: convective 80/60 °C and combined infrared-convective IR (100 W) + 60 °C / 60 °C. Based on the study of the kinetics of moisture exchange in the combined convective-infrared mode of drying apple slices, a formula for calculating the total duration of the process was obtained. The difference between the experimental and theoretical values of the drying time does not exceed 3%. The analysis of the constructed dependences of the Rebinder's number confirms the energy efficiency of the recommended modes of drying apple slices. The resulting product under the developed stepwise drying regimes has high recoverability (78...80%) and organoleptic characteristics: balanced taste, natural aroma, and light cream colour inherent in the raw material.