Effect of ohmic heating on electrical conductivity and hydrogen ion concentration of litchi juice

New technologies like ohmic heating for thermal processing of liquid foods are of great industrial and scientific interest. This study investigates the effects of ohmic heating on electrical conductivity (EC) and hydrogen ion concentration (pH) of litchi juice. The measurements were made for different concentrations (100, 90, 80, 70, 60%) at different voltage gradients (24, 20, 16, 12, 8V/cm) in the temperature range of 14° to 70°C. The measured electrical conductivity showed a linear fashion with temperature and the results indicated that the effect of voltage gradient was statistically significant on the ohmic heating rate (p<0.05). Changes observed in the pH of juice at room temperature were statistically non significant (p>0.05) before and after ohmic heating. The range of electrical conductivity and pH were 0.012 to 0.174 S/m and 2.81 to 3.64, respectively. The measurements of these parameters during ohmic heating are important in designing of ohmic heaters.