Determination of the percentage of ethanol produced by Saccharomyces cerevisiae from semi-purified glycerin

Abstract

The percentage of ethanol produced by Saccharomyces cerevisiae yeast in semi-purified glycerin at three concentrations (2.8%, 5%, 10%) was determined. Two phases were established: An aerobic phase evaluating temperatures of 20°C and 37°C with an inoculation rate of 4% and 1vvm (volume/volume of medium per minute) and an anaerobic phase at a temperature of 10°C, which were monitored for a period of 36 hours. The main kinetic parameters such as specific growth rate, doubling time and the percentage of ethanol produced by the Winnick technique were determined. The results showed that the best temperature to produce biomass of S. cerevisiae is given around 20°C with concentrations of 1.30x10 8 cells/ml with a maximum peak biomass production at 21 hours, which differ significantly from the other treatments evaluated (Sig. = 0.000). The highest production of ethanol was obtained in the treatment of 20% glycerin and 10% of inoculum of the microorganism (p<0.05) at a temperature of 10°C, corresponding to 176.87mg of ethanol/ml of glycerin. Therefore, the viability of this agroindustry by-product is deduced as an alternative source for the biomass and ethanol production from Saccharomyces cerevisiae.