Table of Contents
ISRN Renewable Energy
Volume 2013, Article ID 107851, 11 pages
http://dx.doi.org/10.1155/2013/107851
Research Article

The Production of Bioethanol from Cashew Apple Juice by Batch Fermentation Using Saccharomyces cerevisiae Y2084 and Vin13

1School of Chemical & Metallurgical Engineering, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, Johannesburg 2000, South Africa
2School of Molecular & Cell Biology, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, Johannesburg 2000, South Africa

Received 28 March 2013; Accepted 20 April 2013

Academic Editors: C. Koroneos, F. E. Little, and J. Zhang

Copyright © 2013 Evanie Devi Deenanath et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Bioethanol as a fossil fuel additive to decrease environmental pollution and reduce the stress of the decline in crude oil availability is becoming increasingly popular. This study aimed to evaluate the concentration of bioethanol obtainable from fermenting cashew apple juice by the microorganism Saccharomyces cerevisiae Y2084 and Vin13. The fermentation conditions were as follows: initial sugar = 100 g/L, pH = 4.50, agitation = 150 rpm, temperatures = 30°C (Y2084) and 20°C (Vin13), oxygen saturation = 0% or 50%, and yeast inoculum concentration = ~8.00 Log CFU/mL. The maximum ethanol concentration achieved by Y2084 was 65.00 g/L. At 50% oxygen the fermentation time was 5 days, whilst at 0% oxygen the fermentation time was 11 days for Y2084. The maximum ethanol concentration achieved by Vin13 was 68.00 g/L. This concentration was obtained at 50% oxygen, and the fermentation time was 2 days. At 0% oxygen, Vin13 produced 31.00 g/L of ethanol within 2 days. Both yeast strains produced a higher glycerol concentration at 0% oxygen. Yeast viability counts showed a decrease at 0% oxygen and an increase at 50% oxygen of both yeast stains. Other analyses included measurement of carbon dioxide and oxygen gases, process monitoring of the fermentation conditions, and total organic carbon. Gas analysis showed that carbon dioxide increased in conjunction with ethanol production and oxygen decreased. Process monitoring depicted changes and stability of fermentation parameters during the process. Total organic carbon analysis revealed that aerobic fermentation (50% oxygen) was a more efficient process as a higher carbon recovery (95%) was achieved.