Citric acid production from brewers spent grain by Aspergillus niger and Saccharomyces cerevisiae

Abstract

Production of citric acid by submerged fermentation of brewers spent grain with A. niger and S. cerevisiae was investigated. The effect of the initial pH and presence of methanol on the rate of production was determined. The highest citric acid concentration was produced by A. niger at initial pH of 4.5 in the presence of methanol with a value of 0.512%, while fermentation with S. cerevisiae yielded a highest concentration of 0.312% citric acid. There were significant differences (P≤ 0.05) in the amount of citric acid produced and biomass generated during fermentation with and without methanol. However, there was no significant difference in the biomass production at different pH (P≥0.05).