Volume 5, No. 2, 2017

Due to the increasing energy demands in the country, and the risk of environmental pollution associated with the use of expensive fossil fuel, attempts are being made to replace this expensive energy source with non-conventional and cheaply sourced feedstock which is not edible for alternative energy source. This study looked at using wild cocoyam starch (Xanthosoma esculenta), for ethanol production, the technology of which is also environmental friendly. Wild cocoyam corms (Xanthosoma esculenta) were harvested from bushes in Nnamdi Azikiwe university premises, in Awka, Anambra state. These corms were peeled, washed and sun dried for 4 days. The dried cocoyam corms were ground to powder and 200 grams of the cocoyam starch was weighed out and dissolved in 1000 ml of distilled water. The corm mash was subjected to gelatinization by heating at temperature of 850C for 30 min. Liquefaction was carried out using 5 ml of purified thermostable alpha-amylase (termamyl) that is active and stable at the same temperature of gelatinization. The resulting dextrose solution was cooled at 60 0C and subjected to saccharification using 5 ml of purified amyloglucosidase for 2 days. At the end of saccharification, the medium was filtered and the resultant wort was pitched with 30 ml of Saccharomyces cerevisiae with cell count of 4.32×103 cells/ml. Fermentation started at pH of 5.4 and specific gravity of 1.080 and completed after 8 days with pH of 3.9 and specific gravity of 1.008. The fermented broth was subjected to distillation, and the alcohol content produced thereafter was 19.32%. The result showed that wild cocoyam corms can readily be used for ethanol production.

Keywords: Bio-ethanol, Cocoyam corms, Distillation, Enzymes, Fermentation, Renewable energy