Sugar Conversion Yield Research Articles

Effect of manganese on Lactobacillus casei fermentation to produce lactic acid from whey permeate

Batch fermentations were performed to investigate the effect of manganese addition, in the form of MnSO 4·H 2O, on the performance of Lactobacillus casei for producing l-lactic acid from whey permeate supplemented with yeast extract. There was a particular emphasis on evaluating how little yeast extract and MnSO 4·H 2O is required while still obtaining high sugar conversion and lactic acid yield, as nutrient supplementation is a raw material cost and can lead to extra residual impurities remaining after fermentation. The addition of MnSO 4·H 2O had a significant beneficial affect with the fermentation time being reduced from 120 to 24 h for permeate supplemented with 0.50%w/v yeast extract. Fermentations were performed with MnSO 4·H 2O concentrations in the range of 0.001–0.03 g/l. From 0.005 to 0.03 g/l, the fermentation performance was very similar, however at the low concentration of 0.001 g/l, the fermentation was significantly slower. With MnSO 4·H 2O addition, the yeast extract concentration was reduced to 0.30%w/v while still maintaining high sugar conversion and lactic acid yield, however the fermentation was slower at 37 h. At 0.1%w/v yeast extract supplementation, the fermentation performance was poor with only 67% sugar conversion after 150 h of fermentation.

Pilot-scale multi-stage multi-feeding continuous ethanol fermentation using non-sterile cane molasses

Non-aseptic fermentation of a 28 brix cane molasses solution was successfully carried out in a pilot-scale 5-stage multi-feeding continuous system for 30 days. The effluent ethanol concentration, overall volumetric productivity and sugar conversion yield averaged 8.54 % (v/v), 5.35 g/L-hr and 92.4 % of theoretical, respectively.