DOI: 10.36347/sajb.2018.v06i12.006

Pages: 773-780

The aim of this work was to optimize the microbial hydrolysis of watermelon fruit peels for bioethanol production. The watermelon fruit peels as an alternative and cost effective feedstock for bioethanol production was also studied. Proximate analysis showed that the dried peels contained 31% Extractives, 16% Lignin, 26% Cellulose and 24% Hemicellulose. The fruit peels were pretreated at 121oC for 1 hour prior to hydrolysis and fermentation. Hydrolysis was carried out using Aspergillus niger for 5 days and Baker’s yeast Saccharomyces cerevisiae was used for the fermentation. The optimization was done using a designed experiment MINI TAB. Analysis of variance ANOVA was used to test for the significance of Designed experiment. The results of the analysis showed that temperature (28oC), time (5 days), and pH (5.0) significantly (p˂ 0.05) affected the yield of reducing sugar in the hydrolysis of watermelon fruit peels. The result equally showed that temperature, Days, and pH were significant (p˂ 0.05) factors for hydrolysis. The highest reducing sugar yield was 1.93 ± 0.01 g/L at 28˚C, pH 5.0 and 5 days of hydrolysis. The concentration of the bioethanol produced was determined using the potassium dichromate method. The result therefore revealed the highest bioethanol yield to be 0.16 ± 0.017 mg/L. This Study revealed the optimum conditions for hydrolysis of watermelon peels using Aspergillus niger for high bioethanol production and yield are 28˚C, 5 days, and pH of 5.0.