Bioethanol yield from farm residue of Abelmoschus esculentus (okra) using Saccharomyces cerevisiae: A preliminary assessment

Abstract

The use of agricultural wastes and cellulosic materials for bioethanol is increasingly gaining acceptance due to its environmental friendliness and economic advantage among other factors. The present study assesses the potentialsand usability of dry okra (Abelmoschus esculentus Moench) straws in ethanol production using Saccharomyces cerevisiae.Rate of sugar consumption and ethanol yield of the fermenting system were determined every 24 hours for 5 days. Fermentation efficiency at different pH and temperature, amount of ethanol distilled from the fermented syrup and its purity were also determined. The results showed sugar consumption was directly related to ethanol yield which increased progressively to climax at 96 hours beyond which it declined. However, pH decreases with increase in fermentation time. Optimum sugar consumption and ethanol yield was achieved at 96 hours with highest fermentation efficiencywithin pH 4.2-3.7 and at temperature 37oC. Final distilled ethanol yield (collected at 80-84oC) from250 ml fermented syrup of okra was 31.8 ml (12.58%). Percentage purity was found to be about 93% with specific gravity of 0.7618 KgL-1. The study concluded that if fermentation of okra straw is optimized, it could be a potential raw material to supplement the use of feedstocksfor bioethanol production.