Effect of Saccharomyces cerevisiae ATCC 9763 concentration and fermentation time on bioethanol content from corn stover crude cellulose substrate

Abstract

Corn stover is a waste from the corn plant that dried in the fields after the corn cobs were harvested. From many corn wastes produced, there is very little utilization to corn stover. Delignified corn stover contains 65.46% cellulose, 14.58% hemicellulose, and 8.66% lignin. Lignocellulosic biomass is very difficult to biotransform, therefore it must be delignified to break the bonds between cellulose, hemicellulose, and lignin. Then the cellulose is converted into sugars by saccharification using crude cellulose enzymes so it can be converted into bioethanol through a fermentation process using simultaneous saccharification and fermentation (SSF) method. This study aims to determine the concentration of Saccharomyces cerevisiae ATCC 9763 and the optimum fermentation time in order to obtain high content of bioethanol from corn stover. Bioethanol production at different concentrations of S. cerevisiae and fermentation time uses a factorial randomized block design (RBD) consisting of two factors. The first factor was the concentration of S. cerevisiae which consisted of 3 levels, namely 3%, 5%, and 7% (v/v). The second factor was the fermentation time which consists of 4 levels, namely 24 hours, 48 hours, 72 hours, and 96 hours. Observed variables included pH value, total dissolved solids, reducing sugar content, and ethanol content. The data obtained were analyzed for its diversity using analysis of variants (ANOVA) and continued with the HSD Tukey. The results showed that the concentration of S. cerevisiae 7% (v/v) and a fermentation time of 96 hours was the best treatment to obtain a maximum ethanol content of 7.53 ± 0.330 g/L, with a final pH value of 4.25 ± 0.07, total dissolved solids 2.9 ± 0.14 °Bx and reducing sugar content of 0.334 ± 0.03 g/L. Increasing the concentration of S. cerevisiae and fermentation time can increase the ethanol content.