Assessment Of The Yield Of Microbial Fermented Ripe And Unripe Pawpaw For Bioethanol Production

Abstract

The production of ethanol from Carcia papaya (pawpaw) fruit pulp using dried active baker's yeast strain (Saccharomyces cerevisiae) and isolated yeast from ripe pawpaw pulp was investigated using standard methods. Papaya fruits (ripe and unripe) were collected, washed, and peeled. The pulps were then collected and blended aseptically. Cleaned sterile cheese-cloth was used to sieve the two fruit pulps and the extracts fermented separately with the two yeast broth cultures. The effects of yeast concentration, duration of fermentation, pH, temperature, and different yeast supplements as they relate to the optimization of ethanol production were determined. The fermented pawpaw fruit pulps produced an ethanol content of 8.21% and 4.26% (v/v) for ripe and unripe pawpaw fruit, respectively. Physical and chemical properties of the pawpaw pulp showed that the initial pH of 4.6 was obtained before the start of fermentation with a reducing sugar value of 6.92±0.02. The results of this work show that the rate of alcohol production through fermentation of pawpaw fruit pulp by isolated yeast strain (Saccharomyces spp) increases with fermentation time and peaks at 72 hours. It is also increased with yeast concentration at the temperature of 30°C. An optimum pH of 4.6 was found to be ideal for the fermentation.