ENHANCEMENT OF THE PERFORMANCE OF SOUR CHERRY JUICE CONCENTRATION PROCESS IN VACUUM EVAPORATOR BY ASSISTING OHMIC HEATING SOURCE

Sour cherry juice was concentrated to 65% TSS content by using ohmic heating assisted vacuum evaporation (OVE) at voltage gradients (10, 12, 14 V/cm) and vacuum evaporation (VE). The change of performance efficiencies (energy/exergy) of OVE process depending on the voltage gradient applied and the increase in TSS content during the process were investigated by taking into account of both process and system boundaries, and compared with those of VE process. During this process, total energy consumption decreased as the voltage gradient increased, but it increased as TSS content increased. System boundary based efficiencies were lower than process based ones. Maximum efficiency was obtained for 14 V/cm. Improvement potential values increased as TSS content increased but the voltage gradient increased. The assistance of ohmic heating to VE increased the performance of the evaporation process in terms of energy and exergy efficiencies, and decreased the improvement requirements of the system.