Pretreatment and Hydrolysis of Brewer's Spent Grains

摘要

Brewer's spent grains (BSG), the voluminous residue after mashing, contains on dry weight basis about 40-50 % polysaccharides. For the recovery of soluble carbohydrates from BSG different physical, thermal and enzymatic treatments were used to solubilize the polysaccharides in BSG. Heating by microwave radiation to 160 ℃ in the presence of 0.1 M HCl released 35% of the material in the form of reducing sugar, indicating that about 80% of the polysaccharides were hydrolyzed. Nevertheless, 0.1 M acetic acid will even solubilize 30% of the material as oligosaccharides on a prolonged incubation when pretreating the spent grains by extrusion cooking. A combination of the enzymes Ceremix Plus MG and CelluPract AL 70 achieved an almost 25% release of saccharides after 4 hrs of incubation at 50 ℃. A combination of extrusion cooking and enzymatic hydrolysis seems to be a very promising procedure.