Production of Ethanol from Cassava and Yam Peels Using Acid Hydrolysis

Samson Olayemi, Adeola Ibikunle, Joy Olayemi


Energy from fossil fuels has played a very important role in our lives, but such an important role has been clouded out due to the environment hazards caused from fossil emissions. This has led to a new dimension in energy utilization known as renewable energy fuels. To fully support this type of energy from biological mass, adequate biomass source must be harnessed. This work thus was carried out with a view of utilizing some locally available biomass wastes as an alternative source of ethanol. The production of ethanol from cassava and yam peels was examined using acid hydrolysis at two different temperatures and fermenting with two different strains of saccharomyces cerevisiae (baker′syeast and freshly isolated yeast).Fermentation was allowed for about 5 days after which ethanol was recovered by distillation (at 78 OC). Iodoform test and gas chromatography were used, just to confirm that the distillates were ethanol. Cassava peels hydrolyzed at room temperature produced higher yields of ethanol (11.30% and 8.63%). Fermentation with freshly isolated yeast produced more yield of ethanol both at room temperature (11.30%) and at 80 OC (6.15%) than those fermented with baker′s yeast. Yam peels also produced more ethanol at room temperature than at 80 OC using either of the two enzymes for fermentation (21.72% and 27.08%). Moreover, the use of baker′s yeast for fermentation produced more yield of ethanol from yam peels. For the mixtures by proportion, only the ratio of 2:1 of cassava to yam peels (C₂Y₁) produced a higher yield of ethanol at room temperature (60.52% and 13.39% at room temperature using baker′s yeast and freshly isolated enzymes respectively). The other mixtures [(C₁Y₂) and (CY) sets of samples] gave higher yields of percentage ethanol at 80 OC than at room temperature. Every other sets of samples gave higher yields at room temperature. Generally, most of the samples hydrolyzed better at room temperature except for C₂Y₁ and CY sets of samples. The highest yield of ethanol was produced by (C₂Y₁) when hydrolyzed at room temperature using baker′s yeast (60.52%).


Ethanol yield; Hydrolysis; Energy; Temperature; Saccharomyces cerevisiae.

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