Technical ethanol production from waste of cereals and its products using a complex enzyme preparation

Abstract

AbstractThis paper describes a method for hydrolysing the polysaccharides from cereal‐derived waste to yield a sugar feedstock suitable for fermentation into technical ethanol using a complex of amylolytic and hemicellulolytic/cellulolytic enzymes. The enzymatic treatment of raw materials was carried out by liquid concentrated amylase and glucoamylase in combination with xylanase, containing also cellulase and glucanase activities. Gas chromatography was used for qualitative and quantitative analysis of end‐products. Apart from ethanol, also methanol, propanol, butanol, isoamyl and amyl alcohols, acetaldehyde, ethyl acetate and methyl acetate were found in the distillate. The optimal composition of amylase, glucoamylase and xylanase was selected, dependent on the raw material. The maximum ethanol concentration reached after fermentation of rye and wheat bran was 44 g L−1 and for rye and wheat grain it was 73 and 69 g L−1 respectively. By applying a complex preparation of amylolytic and hemicellulolytic/cellulolytic enzymes to cereal and cereal residues, it was possible to increase the ethanol yield by 20–45%, thereby decreasing the content of higher alcohols by 34% and significantly decreasing the methanol concentration, in comparison with a reference sample without xylanase preparation. Copyright © 2006 Society of Chemical Industry