Effect of varying fermentation parameters in bioethanol production from pomelo peels

Abstract

Pomelo peels, a lignocellulosic material, exhibit potential in bioethanol production due to its high fermentable sugar content, lignin, and cellulose content. In this study, the researchers used pretreated pomelo peels using phosphoric acid and acetone to optimize the bioethanol yield through enzymatic hydrolysis and simultaneous saccharification and fermentation; where pH, amount of substrate, and yeast concentration are the parameters weighed. Optimal ethanol yield of 11.84% was obtained at pH 3.5, 10 mL of substrate, and a yeast concentration of 15%. A 2k factorial design was used to analyze the effect of varying parameters. Dilute acid pretreatment significantly impacted alpha cellulose, acid insoluble lignin, and moisture. At 75% acid dilution, acid insoluble lignin and extractives were affected, while hemicellulose and acid soluble lignin changed at 80% concentration. Amount variation of Aspergillus niger significantly affects the extraction of sugar content of pomelo peels. The optimum condition in reducing sugar analysis, 25.38%, was achieved after using a 75% acid pretreatment and 12 g of enzyme. The concentration of yeast has a significant effect on the percent ethanol yield after fermentation; in contrast, pH and amount of substrate have minor effects. Design-Expert application was used for statistical analysis, while Minitab 18® for analysis of variance. Using response surface methodology, a valid mathematical model with high desirability was generated.