Solid-state fermentation ethanol production

A solid-state fermentation process for the production of ethanol from apple pomace by Saccharomyces cerevisiae was described by Khosravi and Shojaosadati (2003). A moisture content of 75% (wt/wt), an initial sugar concentration of 26% (wt/wt), and a nitrogen content of 1 % (wt/wt) were the conditions used to obtain 2.5% (wt/wt) ethanol without saccharification and 8% (wt/wt) with saccharification. The results indicate that... 

Yu, J., Xuzhang, Tan, T. (2008). Ethanol production by solid state fermentation of sweet sorghum using thermotolerant yeast strain. Fuel Processing Technology, 89, 1056—1059. 

Rottenbacher, L., Schofiler, M. and Bauer, W., Modelling a solid-state fluidized bed fermenter for ethanol production with S. cerevisiae, Bioproc. Eng., 2 (1987) 25-31. 

Khosravi, K. and Shojaosadati, S. A. (2003). A solid state of fermentation system for production of ethanol from apple pomace. Fanni Muhandisi-i Mudarris 10,55-60. 

Amyl alcohols occur in eight isomeric forms and have the empirical formula CjHnOH. All are liquids at ambient conditions except 2,2-dimethylpropanol (neopentyl alcohol), which is a solid. Almost all amyl alcohols are manufactured in the United States by the hydroformylation of butylenes. Yeast fermentation processes for ethanol yield small amounts of 4-methyl-l-butanol (isoamyl alcohol) and 2-methyl-1-butanol (active amyl alcohol, scc-butyl-carbinol) as fusel oil. However, when the amino acids leucine and isoleucine are added to sugar fermentations by yeast, 87% and 80% yields of 4-methyl-l-butanol and 2-methyl-l-butanol, respectively, are obtained (Fieser and Fieser, 1950). These reactions are not suitable for commercial applications because of cost, but they do indicate the close structural relationship between these C5 amino acids and the C5 alcohols. The reactions occur under nitrogen-deficient conditions. If a nitrogen source is readily available, the production of the alcohols is lowered considerably. 

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