Optimization of Yeast Inoculum and Density for Alcohol Production from Red Sorghum Wort

Optimizing fermentation parameters is essential for improving alcohol production in sorghum-based brewing systems. This study investigated the combined effects of wort density and Saccharomyces cerevisiae inoculation rate on alcohol production from red sorghum malt using Response Surface Methodology (RSM). A full factorial 3 × 3 design was applied, testing wort densities of 14, 16, and 18 °P and yeast inoculation rates ranging from 1 to 3 mL, with alcohol content (% v/v) as the response variable. Both factors significantly influenced ethanol production, with inoculation rate showing the strongest effect. The fitted quadratic model adequately described the experimental data and exhibited a non-significant lack of fit. Response surface analysis indicated that the maximum alcohol content was reached at the upper boundary of the experimental domain. Under optimal conditions (18 °P and 3 mL inoculum), an alcohol content of 5.02% (v/v) was obtained. These results emphasize the importance of balancing fermentable sugar availability with sufficient yeast biomass to enhance ethanol production and provide a useful framework for optimizing red sorghum fermentation under moderately high-gravity conditions