Bioethanol production from sugarcane molasses by instant dry yeast (effect of pretreatment and fermentation temperature)

Abstract

Some bioethanol industries in Indonesia that use sugarcane molasses as raw material often face low level of ethanol content from fermentation process. The molasses condition and the temperature fluctuation are supposed to be the cause. This research aimed to determine the effect of sugarcane molasses pre-treatment with H2SO4 and fermentation temperature in bioethanol production by using instant dry yeast of Saccharomyces cerevisiae. Factorial Randomized Block Design with 2 factors was used in the research. The first factor was pre-treatment effect in sugarcane molasses (with and without pre-treatment) and the second was fermentation temperature (29°C, 32°C and 35°C). The data were analysed using analysis of variance or ANOVA and continued with further test Duncan Multiple Range Test or HSD (Honestly Significant Difference) with confidence interval of 5%. The best treatment was determined using Multiple Attribute Test. Results showed that sugarcane molasses pre-treatment with H2SO4 and fermentation temperature had a significant effect (α = 0.05) on bioethanol production. The best result was obtained from sugarcane molasses medium that given H2SO4 pre-treatment and fermentation temperature of 32°C with total decrease value of total soluble solids (% brix) of 10.9% brix, total decrease sugar of 12.15%, reducing sugar consumption of 57.21 g/L, ethanol content of 8.30% and yield ethanol of 68.67%.