Fungal population and physicochemical properties of bioethanol produced from cassava (<i>Manihot esculenta</i>)

Abstract

The quest for affordable and environmentally friendly fuel has led to the production of bioethanol from agricultural products. This study was undertaken to produce alcohol from cassava by the fermentative action of Aspergillus niger and Saccharomyces cerevisiae. The fermentation process comprised of two (2) set ups- one was fermented by Aspergillus niger and the other was fermented by Saccharomyces cerevisiae. The fermentation process lasted for 12 days and it was distilled on the 14th day. The process was monitored and controlled by carrying out physicochemical (pH, temperature, specific gravity, alcohol content) and microbiological analyses using standard methods. There was a decrease in the pH for both set ups during the course of the fermentation. The temperature was between 25.0oC to 30.5oC for both setups. The specific gravity decreased during the course of the fermentation from 1.03 to 0.01 which led to an increase in the alcohol content from 0 to 55% for the setup that involved Aspergillus niger and 1.02 to 0.03 which led to an increase in the alcohol content from 0 to 50% for the setup that involved Saccharomyces cerevisiae. There was an increase in the total fungal count from 4.4 ×102 to 5.9×102 CFU/ml from day1 to 7 and a decrease from 5.9 ×102 to 0 CFU/ml from days 7 to after distillation for the setup that involved Aspergillus niger. There was also an increase in the total yeast count from 1.6 ×102 to 2.9 ×102 from days 1 to 7 and a decrease from 2.9 ×102 to 0 from days 7 to after distillation for Saccharomyces cerevisiae. This study shows that alcohol can be successfully produced from cassava using Aspergillus niger and Saccharomyces cerevisiae.