Enzymatic hydrolysis of beer brewers' spent grain and the influence of pretreatments

The enzymatic saccharification of plant material has been shown to be of interest in various fields, such as the production of fruit juices(1,2) and the utilization of biomass.(3) A combination of cellulase, pectinase, and hemicellulases is usually used because of the chemical composition of the matrix of plant cell walls.For apples, beet pulp, and potato fiber, almost a complete hydrolysis of polysaccharides is obtained by combining cellulose and pectinase. For nonparenchymatic tissue, the situation is somewhat different: pectin is a minor component and the hemicellulose content is much higher. Enzyme action is restricted by the lignin barrier and by the high crystallianity of cellulose in this material. For such materials, mechanical, thermal, or chemical pretreatments are necessary to achieve hydrolysis.(4,5)This communication describes various enzymatic treatements and chemical and physical pretreatemtn, using brewers' spent grain as substrate. Spent grain is the residue of malt and grain which remains in the mash-kettle after the liquefied and saccharified starch has been removed by filtration.