Regression analysis for predicting the fermentation state of packaged Kimchi using a colorimetric indicator

The application of a colorimetric indicator for monitoring the degree of fermentation in Kimchi was studied. Changes in total color difference (TCD) occurred continuously from the initial to final fermentation stage with a maximum TCD value of 36.08 ± 0.72 after 28 days. The experimental data for the converted color response function, F(Xc) were demonstrated to be more linear (R2 = 0.986) than for TCD values. The coefficients of determination of pH: F(Xc) (R2 = 0.9583) and titratable acidity: F(Xc) (R2 = 0.9828) were sufficient to meet the zero-order reaction. Results of standardized residuals evidenced their normal distribution, indicating that 95% of the residuals of predicted pH or titratable acidity were in the range of −1.96 to 1.96. The coefficients of determination between predicted- and observed data were 0.841 (pH) and 0.912 (titratable acidity). Based on regression analysis, the colorimetric indicator could thus be applied as a Kimchi fermentation indicator.