3.1.3. L-lactic acid fermentation of enzymatic hydrolysates
Fig. 3 shows the fermentation profiles of R. oryzae grown on XOS waste residue hydrolysate at various substrate loadings. The fermentation pH was maintained at >6.0 by adding calcium carbonate. There was not much difference in the pH profile among the different substrate loadings, except for the 20% loading that had a higher initial pH of ~7.5 due to more CaCO3 were added. Nevertheless, the pH in the range of 5.5-7.5 should have a minimal effect on the fermentation [6]. In general, little or no lactic acid was produced in the first 12 h, indicating that glucose was mainly used to generate fungal biomass. Thereafter, a rapid consumption of glucose with fast accumulation of L-lactic acid and ethanol occurred until all glucose had been consumed, except for the 20% loading, in which lactic acid production ceased before glucose depletion. During the