Akponah, E. And Akpomie, O.O.
The feasibility of bio-ethanol production from yam, potato and cassava root peels was investigated. Slurry of each peel was saccharified using acid, commercially available α- amylase and Aspergillus niger which was screened and certified for amylase production. Subsequent fermentation by Saccharomyces cerevisiae followed at room temperature for 72 hours. Composition analysis revealed that yam, potato and cassava root peels contained 46, 96 and 114.5 (mg/g) starch respectively. Glucose yield obtained after hydrolysis of yam peels using amylolytic fungi, enzyme and acid were 51.6, 48.7 and 78.1 (mg/g) respectively. Similarly, glucose levels of the respective potato peel hydrolysates were 160.8, 90.7 and 248.3 (mg/g). Saccharification of cassava root peels resulted into glucose concentrations of 210.4 mg/g, 110.4 mg/g and 250.0mg/g in amylolytic fungi, enzyme, and acid hydrolysates respectively. The ethanol yield after fermentation of yam peels hydrolysed using amylolytic fungi, enzyme and acid were 1.68, 0.56 and2.7 (%v/w) respectively. Ethanol yield from potato peels were 4.02%v/w (amylolytic fungi hydrolysate), 1.94% v/w (enzyme hydrolysate) and 9.38% v/w (acid hydrolysate). Fermentation of the respective cassava peel hydrolysates resulted in 10.5%v/w, 4.07% v/w and 17.52% v/w ethanol. Results obtained suggested that increasing the fermentation duration did not result in a corresponding increase in ethanol production hence maximum ethanol yield in various hydrolysates was at the 24th hour of fermentation following the order acid hydrolysates > amylolytic fungi hydrolysates > enzyme hydrolysates. Also, in terms of substrate yield, highest ethanol production was from cassava root peels, followed by potato peels while yam peels yielded the least ethanol concentration. This research therefore, indicates that these peels could serve as cheap sources of glucose which can be fermented locally for bio-ethanol production especially in areas where they are in abundance.
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