Effects of altering fermentation parameters on glycerol and bioethanol production from cane molasses

Current bioethanol production processes do not produce more than approximately 13g1(-1) glycerol at a purity of 11% total solids in the fermented mash. Such quantities are not sufficiently high for economic exploitation unless very-large-capacity plants are involved. It was envisaged that the ratio of glycerol to bioethanol could be altered in favour of glycerol by adjusting such fermentation parameters as osmotic pressure (water activity), pH, temperature and yeast cell inoculum. At 39.9degrees brix, pH 8.7, 38degreesC, 90.7 atm. and 120 x 10(6) yeast cells ml(-1), glycerol formation in fermented mash increased to 56 g 1(-1) at a purity of 14% total solids. The potential for high glycerol production, hence higher revenue, has been demonstrated. Adoption of this technology could have a significant positive economic impact on existing or new biomass-to-ethanol plants. (C) 2002 Society of Chemical Industry.