The ohmic and conventional heating methods in concentration of sour cherry juice: Quality and engineering factors

In the present study, ohmic and conventional heating methods were applied to concentrate sour cherry juice. The heating rate of ohmic method increased ten-fold compared with conventional heating. The temperature gradient showed a 1.5 degrees C difference between the temperatures of the medium in the vicinity of the two electrodes. The electrical conductivity of sour cherry juice at voltage levels of 30-50 V ranged from 0.70 to 2.52 S/m. The higher values belonged to the end of the process and lower voltages. Acidity measurement showed no significant difference among the applied voltages in ohmic heating with the exception of 35 V. The effect of conventional heating on the color change of sour cherry juice was more than that of ohmic heating.

Automated summary

The study found that ohmic heating had a faster heating rate and smaller temperature gradient compared to conventional heating, but the electrical conductivity of sour cherry juice varied significantly with voltage levels. Acidity measurement results showed no significant difference among applied voltages in ohmic heating except at 35V. Conventional heating had a greater impact on color change of sour cherry juice than ohmic heating.