Use of saccharose and structural polysaccharides from sugar beet biomass for bioethanol production

In addition to saccharose, sugar beet root contains a lignocellulosic fraction, which is not used in the process of sugar production and remains in sugar beet pulp. There is a great interest in using the polysaccharides (cellulose, hemicellulose) present in this raw material for the production of bioethanol. The objective of this study was to assess the effect of the enzymatic treatment of sugar beet biomass on the hydrolysis of the cellulose and hemicellulose present in its cell walls, as well as its effect on the efficiency of alcoholic fermentation of saccharose and sugars liberated from structural polysaccharides. Its effect on the efficiency of the process of inoculating the fermentation medium with a monoculture or a co-culture of yeast strains fermenting hexose and pentose sugars was also investigated. Our results reveal that in order to enable the utilization of all fermentable sugars in the sugar beet root biomass (saccharose as well as monosaccharides bound in structural polysaccharides), initial enzymatic treatment should be applied, followed by alcoholic fermentation using sequential inoculation with a co-culture of Saccharomyces cerevisiae and Pichia stipitis. These conditions ensure the utilization of hexoses and pentoses (xylose) in alcoholic fermentation, thus enabling the production of 9.9±0.4 kg of ethanol from 100 kg of sugar beet biomass.