Lactic acid production from distiller's grains by simultaneous saccharification and fermentation

The industrial distiller's grains obtained from sorghum to ethanol have the characteristic of abundant nutrient and high cellulose composition, which make it suitable for resource utilization. This study is to use distiller's grains to produce lactic acid by simultaneous saccharification and fermentation(SSF), not only for finding the new way for the reclamation utilization of distiller's grains, but also for searching new low-cost raw materials for lactic acid production. The result showed that lactic acid can be produced from distiller's grains by SSF at 50°C. The reducing sugar consumption and lactic acid production were investigated. The results indicate that the lactic acid conversion rate was appropriately about 77.6%. The dissoluble solid increased after fermentation, which is about one time higher than the initial value. Then single factor test was used to optimize fermentation condition. Maximum concentration of lactic acid which was obtained with adjusting pH by ammonia to 6.0 for every 24h, and the 2.1% inoculum size of lactobacillus casei can reach to 32.8g/L.