Enhanced Lactic Acid Production from Kitchen Garbage by Optimization of Dilute Sulphuric Acid Pretreatment

On the basis of previous studies about lactic acid (LA) production from food waste (‘cooked’ waste from canteens and restaurants), this study explored LA production from kitchen garbage (KG, ‘raw’ waste from household kitchens) for the first time. Considerable pretreatment method for fermentable sugar release in KG was investigated and acid pretreatment was found to significantly increase the conversion of polysaccharide. Further, the conditions of acid pretreatment were optimised through response surface methodology and the polysaccharide conversion rate in KG reached 72.88%. Fourier transform infrared spectroscopy and X-ray diffraction revealed that the hemicellulose and lignin of KG were dissolved, which increased the polysaccharide conversion in KG during acid pretreatment. Finally, the feasibility of LA production from KG hydrolysate with acid pretreatment was investigated and the final LA concentration and yield were 60.28 g/L and 0.31 g/g KG (dry weight), respectively, which were 11% higher than those without acid pretreatment