Investigation and modeling of lactic acid fermentation on wheat starch via SSF, CHF and SHF technology

Abstract

Starch based lactic acid fermentation technology was examined and optimized using a non-amylolitic, mesophilic lactic acid bacterium. Comparing simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) technologies several issues arose and applying the two techniques needed several compromises concerning the overall process time. A combined hydrolysis and fermentation method was developed which incorporate the advantages of SSF and SHF technologies: applying a time delay in inoculation and cutting down hydrolysis time before fermentation, an optimal inoculation and high efficiency was achieved by kinetic model aided experimental work. Experimental verification of the model gave an excellent productivity result: 4.32 g L^-1h^-1 calculated with only the fermentation time, and 2.88 g L^-1h^-1 calculated with the overall time of the two processes. With this method, hydrolysis and fermentation time was successfully reduced, enhancing lactic acid productivity and depressing production cost of this low-value chemical.