SSF Production of L-lactic Acid from Food Waste and Sophoraflavescens Residues

L-lactic acid (L-LAC) production by simultaneous saccharification and fermentation (SSF) of food waste (FW) and sophoraflavescens residues (SFR) at different FW-to-SFR (FSRs) ratios (i.e., 0:1, 0.5:1, 1:1, 1.5:1, 2:1 and 1:0) was investigated. Results from the experiments revealed that co-fermentation of SFR and FW produced more amounts of L-LAC compared with the exclusive fermentation of SFR or FW under the same amount of fermentationsubstrate. It may be attributed to the synergistic effect of the co-fermentation. The highest L-LAC yield was obtained at theFSRsof1.5:1. Besides, experimental results also suggested that the addition of SFR into the fermentation substrate could alleviate the acidification of FW and reduced the yield of the adverse by-products (i.e., ethanol) as well. On the other hand, addition of FW might support nitrogenresourceforLactobacillus casei, minimizing the cost for other nitrogen supplemental raw material (e.g., the yeast extract). The study results provide an important theoretical basis on the resource utilization of FW and SFR.