Optimization of lactic acid fermentation from distillers grains hydrolysates using orthogonal experimental design (OED).

Lignocellulosic biomass-derived sugars is considered to be an economically attractive carbohydrate feedstock for large-scale fermentation of bulk chemicals such as lactic acid (LA). The aim of this study was to investigate the possibility of LA production from distillers grains hydrolysates (DGHs) by the Rhizopus oryzae and to optimize the biological conversion of reducing sugar into LA to evaluate the culture conditions. The effects of factors such as inoculations size, CaCO3 addition, pH value and fermentation time on the lactic acid concentration (LAC) and the reducing sugars utilization rate (RSUR) were researched by the method of orthogonal experimental design (OED). The results show that the optimal fermentation parameters are inoculation size of 3.0% seed culture, CaCO3 addition of 80 g·L, fermentation time of 96 h and culture pH of 6.5. This study provides an encouraging means of producing LA from the low-cost waste distillers grains.