Enzyme-Aided Fractionation of Brewer's Spent Grains in Pilot Scale

Brewer's spent grain (BSG) is an important coproduct of the brewing industry and is generally used in animal feed. Recently, there has been considerable research into the use of enzymes to convert BSG into more value-added products. In this study, the efficiency of enzymatic fractionation of freshly produced BSG was studied in pilot scale. Carbohydrate-and protein-degrading enzymes were applied sequentially to produce three fractions: carbohydrate hydrolysate, protein hydrolysate, and a solid lignin-carbohydrate residue. To minimize microbial contamination, processing was performed at 60°C for 4 hr. In all, 14 and 36% of the original dry matter was liberated by carbohydrase and protease, respectively. The carbohydrate-degrading enzyme cocktail produced cellulose- and hemicellulose-derived mono- and oligosaccharides. The protease treatment released peptide-enriched hydrolysate. Approximately half of the original BSG solids were solubilized during the two-stage enzymatic process. Although the protease efficiently released the majority of BSG proteins, the carbohydrate matrix was much less accessible to enzyme attack. The impact of scale-up to pilot scale was compared with previous laboratory-scale studies, and the results were found to be in good agreement.