Application of response surface methodology (rsm) in optimization of lactic acid fermentation of carrot: influence of addition of salt, additives and growth stimulators

Response surface methodology involving Central Composite Design (CCD) was applied to evaluate the effect of additives and growth stimulators with salt on natural lactic acid fermentation of carrot at room temperature. The variables investigated in this study were salt (2% - 3%), Lactose, MgSO4 + MnSO4 and Mustard (1%,1.5% and 2%) ; and various responses involved were per cent titrable acidity (Lactic Acid), pH, per cent salt and Lactic Acid Bacterial count (LAB count). The statistical analysis of the results showed that, only the treatments having powdered mustard had an appreciable effect on lactic acid fermentation. The best results were obtained in the treatment with 2.5 % salt, 1.5 % lactose, 1.5 % MgSO4 + MnSO4 and 2.0 % mustard. These optimized concentrations increased titrable acidity (1.69% as compared to the lowest value of acidity obtained i.e. 1.50%), lowered pH (2.47 as compared to the highest value of pH obtained i.e.3.30) and increased LAB count (9 X 108 cfu/ml as compared to the lowest value of count obtained i.e.6.13 X 108). The second-order polynomial regression model determined that the desirable characteristics would be obtained at these concentrations of additives. Hence, the values for different additives and growth stimulators optimized in this study could successfully be employed for the lactic acid fermentation of carrot.