Normal gravity rye and triticale mashes, containing 20–21 g of dissolved solids per 100 mL of mash liquid, were fermented with active dry yeast at 27°C. Fermentations were completed within 48 hr for rye, and within 72 hr for triticale. Supplementation of mashes with urea at a concentration of 8 mM accelerated rates of sugar consumption and fermentation, and reduced fermentation time from 48 to 36 hr for rye, and from 72 to 48 hr for triticale. Rye fermented faster than triticale, due to its higher level of free amino nitrogen. Ethanol yields were 356–363 L/tonne of 14% moisture rye grain, and 362–367 L/tonne of 14% moisture triticale. Fermentation efficiencies, which were 90–91% for triticale, and 91–93% for rye, and ethanol yields were comparable to those obtained from wheat and were not affected significantly by urea supplementation. The replacement of wheats by less expensive crops such as rye and triticale would provide good economic opportunities and alternatives for the fuel alcohol industry.

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Cereal Chem. 76(1):82-86The 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 short-ened 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.