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Optimization of Fermentation Temperature and Mash Specific Gravity for Fuel Alcohol Production

¹Department of Applied Microbiology and Food Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada S7N 5A8. ²Corresponding author. Phone: 306/966-5030. Fax: 306/966-8898. E-mail: wangs@skyfox.usask.ca ³Saskatchewan Research Council, 15 Innovation Boulevard, Saskatoon, SK, Canada S7N 2X8. ⁴Department of Crop Science and Plant Ecology, University of Saskatchewan, SK, Saskatchewan.

The effects of fermentation temperature and dissolved solids concentration adjusted by changing mashing water-to-grain ratios on wheat fermentation efficiencies, fermentation times, final ethanol concentrations, and ethanol production rates were studied by using response surface methodology. Final ethanol concentrations in fermentors depended primarily on mash specific gravities. Predictably, increases in fermentation temperatures dramatically reduced fermentation times and thereby shortened fermentation cycles. The highest ethanol production rates were achieved with a high fermentation temperature of 30°C and a low water-to-grain ratio of 2.0. At these settings, an ethanol concentration of 13.6% (v/v) was attained with a fermentation time of 54 hr and an ethanol production rate of 2.45 mL of ethanol/L/hr. Optimization of operating conditions suggested in the current study will provide existing fuel alcohol plants with increased productivity without alteration of plant equipment or process flow.