Problem statement: Dilute sulphuric acid and enzymatic hydrolysis methods were used for sugar extraction. Xylose and glucose sugars were obtained from corn cobs. Approach: Acid hydrolysis of corn cobs gave higher amount of sugars than enzymatic hydrolysis. Results: The results showed that optimal temperature and time for sugar fermentation were approximately 25°C and 50 h by two yeast strains (S. cerevisiae and P. Stipitis) respectively. | OnLine Journal of Biological Sciences 10 2 103-108 2010 ISSN 1608-4217 2010 Science Publications Temperature Optimization for Bioethanol Production from Corn Cobs Using Mixed Yeast Strains Clarence S. Yah Sunny E. Iyuke Emmanuel I. Unuabonah Odelia Pillay Chetty Vishanta and Samuel M. Tessa School of Chemical and Metallurgical Engineering Faculty of Engineering and the Built Environment University of the Witwatersrand Wits 2050 Johannesburg South Africa Abstract Problem statement Dilute sulphuric acid and enzymatic hydrolysis methods were used for sugar extraction. Xylose and glucose sugars were obtained from corn cobs. Approach Acid hydrolysis of corn cobs gave higher amount of sugars than enzymatic hydrolysis. Results The results showed that optimal temperature and time for sugar fermentation were approximately 25 C and 50 h by two yeast strains S. cerevisiae and P. Stipitis respectively. At 20 and 40 C less bioethanol was produced. Bioethanol produced at 25 C was mg mL-1 while at 40 and 20 C were and mg mL-1 respectively. Conclusion Recommendations Data obtained revealed that xylose level decreased from mg mL-1 during the first 50 h of fermentation and complete metabolism of glucose was observed during this time. Xylose and bioethanol levels remained constant after 50 h. Varying the temperature of the fermentation process improves the effective utilization of corn cobs sugars for bioethanol production can be achieved. Key words Bioethanol corn cobs optimization fermentation hydrolysis INTRODUCTION In an attempt to maximize waste product into useful material this article seeks to determine the optimal temperature for large scale bioethanol production from corn cobs. Corn cob a waste product of corn contains large amount of sugars that can be further utilized to produce various compounds Cao et al. 1996 Adesanya and Raheem 2009 . The bioconversion of lignocellulosics to biofuel from cheap non-edible materials such as corn cob for renewal
