Estimation model for electrical conductivity of red grape juice

The equations for predicting the electrical conductivities of red grape juice at different concentrations have been evaluated in this study. Three samples of red grape juice having concentrations of 10.5, 12.5 and 14.5°Brix were ohmically heated by applying three different voltage gradients (10, 12 and 15 V/cm) in the temperature range of 25-80°C. The mathematical models using multiple linear regression analysis indicated that electrical conductivity depended on temperature and concentration. The predictions of electrical conductivities using the mathematical models was found to be highly accurate with R2 value of 0.9975 when compared with the experimental data of red grape juice with concentration of 11.5°Brix. The reducing chi-square (x2) and the root mean square error (RMSE) from the mathematical models were calculated and compared with the experimental data. As the results, multiple linear regressions on the coefficients of the mathematical model of electrical conductivity prediction have given highest values of the R2 and lowest xX and RMSE so the established model was confirmed as highly accurate when estimating electrical conductivities of red grape juice