Ohmic heating of pomegranate juice: Electrical conductivity and pH change

Abstract

Ohmic heating is an alternative fast heating method for food products. In this study, the effect of ohmic heating technique on electrical conductivity, heating rate, system performance and pH of pomegranate juice was investigated. Ohmic heating rate, electrical conductivity, and pH are dependent on the voltage gradient used (30–55 V/cm). As the voltage gradient increased, time, system performance and pH decreased. The electrical conductivity of the sample increased with temperature rise (20–85 °C). The range of electrical conductivity during ohmic heating was 0.209–1.013 (S/m). Among the two models tested to fit the electrical conductivity of pomegranate juice, the linear model gave the best fit for all the data points. Bubbling was observed above 81 °C especially at high voltage gradients. The system performance coefficients for pomegranate juice samples were in the range of 0.764–0.939.