Temperature optimization for bioethanol production from corn cobs using mixed yeast strains

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 11.99 mg mL-1, while at 40 and 20°C were 2.50 and 6.40 mg mL-1 respectively. Conclusion/Recommendations: Data obtained revealed that xylose level decreased from 27.87-3.92 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.