ETHANOLIC FERMENTATION OF BLACKSTRAP MOLASSES AND SUGARCANE JUICE USING VERY HIGH GRAVITY TECHNOLOGY

The fermentability of blackstrap sugarcane molasses was examined under very high gravity (VHG) conditions. Molasses fermentations were carried out over the range of 10.4-47.6% (w/v) dissolved solids. As the concentration of dissolved solids increased, the percentage of sugar actually converted to ethanol decreased. The suitability of molasses as a carbohydrate adjunct for VHG ethanolic fermentation was also studied; molasses was used to raise the dissolved solids content of both clarified wheat mash base and sugarcane juice to VHG levels. Fermentation of such mashes was 90-93% efficient. In VHG wheat mashes prepared with molasses adjunct, yeast extract accelerated the rate of fermentation but had little effect on the final ethanol concentration. Sugarcane juice was not limiting in assimilable nitrogen since yeast extract or urea failed to stimulate the rate of fermentation of cane juice/molasses worts or to increase the final ethanol concentration achieved. This is the first report of the application of VHG technology to fermentation substrates other than wheat, wort, and grape juice. It is concluded that VHG fermentation of saccharine substrates could lead to moderate increases in alcohol concentration as compared to those presently achieved in industry.