Effect of Temperature and Fermentation Time on Yield and Optical Purity of Lactic Acid from Kitchen Waste Fermentation

Batch experiments were carried out to analyze the effect of temperature and fermentation time on lactic acid yield and optical characteristics during the non-sterilized fermentation of kitchen wastes. The results showed that the maximum total lactic acid production rate (0.59 g L-1 d-1) and yield (0.62 g per gram VS) were obtained at 35 ℃ after fermented for 120 h. Lactic acid (calculated as organic carbon) accounted for 78% of the total organic carbon in the fermentation liquid. The L-lactic acid was the predominant isomer form when the fermentation time was less than 120 h. At 35 ℃ and 55 ℃, L-lactic acid concentration decreased with the fermentation time, while at 45 ℃, it increased with the fermentation time and the ratio of L-lactic acid to total lactic acid reached 97% after fermented for 144 h. Fig 4, Tab 1, Ref 21