Processing of wheat bran to sugar solution

In accordance to better exploitation of raw material for bioethanol production we try to find the method for saccharification of problematic cover part of grain, so called bran. The bran consists of three main components: residual starch, hemicellulose and cellulose. Whereas hydrolysis of starch is easy and well solved, there are questions how to optimise hydrolysis of all polysaccharides together, including hernicellulose and cellulose. The bran was treated with starch degrading enzymes (Termamyl 120 L and AMG 300 L) in order to remove the starch from the solid particles and use the starch-free residue for hydrolysis of hernicelluloses to pentoses. This starch-free residue (SFR) was treated with sulphuric acid and high temperature during exact time. Different times of pre-treatment (10-50 min), different temperatures (110-180degreesC) and different concentrations of sulphuric acid (1-4% of weight of slurry) were tested, as well as presence of furfural and 5-hydroxy-methyl-2-furaldehyd (HMF), substances causing inhibition of fermentation, was evaluated. The best yield of sugars (52.1 g/100 g of SFR) was achieved by using 1% of sulphuric acid at 130degreesC for 40 min and this method generates very low content of furfural and HMF (0.28 g/l, resp. 0.05 g/l). (C) 2003 Elsevier Ltd. All rights reserved.