Effect of Incubation Period and Temperature on the Bioethanol Yield Produced from Cassava Peel by Aspergillus niger and Saccharomyces cerevisiae in Submerged Fermentation Process

Abstract

Various agrowastes have been found to be useful in bioethanol production. Microbial activity during the fermentation cycle results in the bioconversion of simple sugars into ethanol and carbon dioxide (CO₂). Large-scale ethanol production has been achieved worldwide using cassava starch. Thus, the objective of this paper was to evaluate the effect of incubation period and temperature on bioethanol yield from cassava peel by Saccharomyces cerevisiae ATCC 204508/S288c and Aspergillus niger KC 329626 in submerged fermentation process. The physicochemical parameters which include the pH, TTA and specific gravity were assayed to determine the optimal condition for the bioethanol yield at different temperature and incubation period. At a substrate concentration of 30 mg/100 ml, Saccharomyces cerevisiae recorded the highest value of bioethanol yield (29.56 ± 0.05) and Aspergillus niger (26.52 ± 0.07) at day 4, while the lowest yields were obtained on day 1 for Aspergillus niger (19.00 ± 0.50) and 20.88 ± 0.04b for Saccharomyces cerevisiae of the bioethanol production process. The recorded mean values for SG (kg/m³) were close, the pH and reducing sugar decreased as the incubation period (days) increases, while the TTA (ml) and the ethanol output (g/ml) also increased. At day 4 of the production series, the optimum temperature at which the maximum bioethanol yield was recorded was found to be at 30 °C. This study thus revealed that cassava peel may be processed and utilized as a alternative source for commercial and industrial bioethanol production as long as the proper conditions are met for the optimization of the fungal strain used.