ABSTRACT:

Fermentation of cassava for 72 h into bioethanol was carried out to determine the effect of variety (sweet or bitter) and surface area (diced or grated) on the microbial and physicochemical compositions. The grated cassava had higher bacterial and fungal counts of 6.88 x 105± 0.02 cfu/ml and 2.84 x 105± 0.03 cfu/ml for the sweet variety and 6.29 x 105± 0.03 cfu/ml and 2.55 x 105± 0.02 cfu/ml for the bitter variety when compared to the diced cassava with 5.34 x 105± 0.24 cfu/ml and 1.41 x 105± 0.01 cfu/ml for the sweet variety and 5.05 x 105± 0.07 cfu/ml and 0.78 x 105± 0.07 cfu/ml for the bitter variety. There was an increase in protein, moisture and fat contents and a decrease in ash, fiber and carbohydrate contents after fermentation. Of the minerals analyzed, calcium, magnesium and phosphate contents were higher in the grated sweet cassava. The pH of the grated cassava was lower than the diced cassava for both varieties. Cyanide content was lower after fermentation for the grated sweet and bitter cassava (7.58 ± 1.32 mgHCN/100g and 20.13 ± 2.28 mgHCN/100g) than the diced sweet and bitter cassava (8.71 ± 4.47 and 21.42 ± 3.01 mgHCN/100g). Bioethanol yield was higher from the grated sweet and bitter cassava (49% and 41%) than from the diced sweet and bitter cassava (36% and 32%). Production of bioethanol, an alternative source of energy to fossil fuels, could be enhanced by increasing the surface area of cassava.