Optimization of lactic acid production from tapioca starch hydrolysate by Lactobacillus casei TISTR 453

Abstract

The influences of calcium carbonate, yeast extract, and manganese sulfate on the production of lactic acid from tapioca starch hydrolysate by Lactobacillus casei TISTR 453 were investigated. All experiments were carried out in a submerged fermentation for 72 h at 37o C with an initial level of reducing sugar at 50 g/l. The amount of calcium carbonate was varied between 0 and 100 g/l in the first experiment and the results indicated that 50 g/l calcium carbonate was optimal. Under the optimal condition, a high lactic acid concentration (31.15 g/l) and the highest lactic acid yield coefficient (YL/S) at 0.73 g lactic acid/g substrate utilized were obtained. To evaluate the effects of yeast extract and manganese sulfate on lactic acid production, response surface methodology (RSM) was employed. The model obtained from RSM predicted a maximum lactic acid concentration (Y) and YL/S at 42.39 g/l and 0.84 g/g substrate utilized, respectively, using 20 g/l yeast extract and 0.05 g/l manganese sulfate monohydrate