ASSESSMENT OF SWEET POTATO PEEL AS A POTENTIAL RAW MATERIAL FOR BIOETHANOL FUEL

Abstract: The feasibility of producing bioethanol from Sweet Potato (Ipomoea batatas) peels using fermentation process was examined. The gelatinized sample of sweet potato was subjected to a two stage enzyme hydrolysis using bacterial alpha-amylase (Amylitic-TS) and fungal alpha-amylase (AMG) to produce fermentable sugar solution. The hydrolyzed liquor was inoculated with Industrial baker's yeast (saccharomyces cerevisiea) and gave ethanol yield of 11.60% after 7 days of fermentation. The efficiency of the fermentation process was evidenced by the decline in the pH and brix level of the fermented sugar solution. The pH dropped from 8.50 to 4.82 and brix level fall from 16.0 to 3.0. The reduced pH enhanced the optimum activity of the yeast. The decrease in the pH enabled the population of fungal to increase significantly from 3.10 X 104sfu/ml to 3.20 X 105sfu/ml after day 7. Conversion of wort to ethanol was optimum at the lowest specific gravity value of 0.9830. This trend can be attributed to steady decline in the brix level as fermentation process progressed.

Keywords: Sweet Potato (Ipomoea batatas), ethanol, enzyme, hydrolysis, Saccharification.