Analysis of the product streams obtained on butanosolv pretreatment of draff

The efficient use of biomass-derived waste streams from the food and drink industry is very important for achieving a circular economy. In this work, a pretreatment based on 1-butanol (butanosolv) was used to fractionate draff, a by-product from the brewing and distilling industries, leading to a solid pulp, a hemicellulose derived-fraction and a pseudo lignin. The pulp was enriched in glucans and showed a 4-fold improvement in enzymatic hydrolysis experiments relative to the starting biomass. The pulp could be fermented in an ABE process producing 32g/100g of solvents. The hemicellulose-derived fraction was analysed by 2D HSQC NMR and found to contain a mixture of predominantly butoxylated monosaccharides. The hydrolase enzymes present in Cellic® CTec3 were used to hydrolyse selectively the glucose and xylose derived butyl β-pyranose monomers. Alternatively, non-selective hydrolysis of both anomers was achieved using TFA/H₂O giving native sugars for fermentation and recovered 1-butanol. A detailed characterization of the pseudo lignin was also achieved.