ETHANOL FERMENTATION FROM MOLASSES USING THERMOTOLERANT YEASTS

Abstract

                Molasses is one of the common raw materials for the industry of bioethanol production. The application of thermotolerant yeasts to produce ethanol from molasses is a quite potential step, promissing to bring many benefits to the ethanol industry, particularly in a country with a tropical climate as Vietnam.

The objectives of this study were to select a number of potential thermotolerant yeasts for ethanol fermentation, and to study favorable conditions for

ethanol production from molasses at high temperature.At 37°C, six strains of yeasts (Y8, Y80, Y81, YVN7,YVN8, and YVN12) were selected as the most ethanol producing strains with the ethanol contents ranging from 5.54 to 6.40% (v/v). The yeast strains of Y8, Y80, Y81, and YVN8 were characterized as Saccharomyces cerevisiae. YVN7 was Candida glabrata, and YVN12 was Torulaspora globosa. The S. cerevisiae Y81 was found giving the highest ethanol produced at 37^oC and 40^oC with the ethanol concentrations of 6.40% (v/v)and 3.17% (v/v), respectively. The favorable conditions for ethanol production at 37°C from molasses of the S.cerevisiae Y81 were determined as follows: 10⁷ yeast cells/ml of inoculum level, initial sugar concentration of 186 g/l, and 6 days of fermentation, which gave the achieved ethanol concentration of 7.36% (v/v).