Optimized lactic acid production from whey using hybrid design and ridge analysis

Cheese whey, a byproduct of dairy industry, is usually considered as a high strength wastewater from environmental point of view because of its high chemical oxygen demand. Production of valuable chemicals from cheese whey has been considered as an attractive option because of its rich nutrient content. This investigation aimed at the optimized production of lactic acid from cheese whey using isolated Lactobacillus plantarum JX183220 under submerged fermentation by applying response surface methodology (RSM) that involved 4-variable hybrid design and ridge analysis. The effect of different process variables such as whey concentration, yeast extract concentration, inoculum size, and pH of the medium were monitored so as to enhance the lactose conversion in whey to lactic acid. By applying 416C version of hybrid design along with ridge analysis, the maximum production of lactic acid was found to be 36.09 g/L at the optimum combinations of process variables: whey concentration (% v/v) 76.96, yeast extract concentration (% w/v) 1.163, inoculum percentage (% v/v) 4.47 , and pH 6.8.