Evaluation of the In Vitro Bioactivities’ Profiles of Brewers’ Spent Grain Protein and Hydrolysates with and without Cellulase Pretreatment

Abstract

Brewer’s spent grain is the residue left after the separation of wort during the beer-brewing process. Although this by-product has been reported to have a high protein content, it is normally treated as waste. This work aims to isolate bioactive hydrolysates from BSG, and then explore their bioactivities. Two groups (A and B) of BSG were subjected to protein extraction using the alkaline extraction method at pH 12, where group A was pre-treated with cellulase, while group B was not pre-treated and was directly extracted. The final isolate yielded 50.18 ± 1.22% recovery of the BSGP from group A and 66.41 ± 0.37% recovery from group B. RP-HPLC profiles showed that the extracted BSGPs are mainly hydrophilic proteins. The proteins extracted by the two methods were hydrolyzed enzymatically using Alcalase and α-chymotrypsin. The hydrolysates obtained displayed blood pressure regulation activity and antioxidant properties, when assayed with angiotensin-converting enzyme assay, 2,2-diphenyl-picryl-hydrazyl assay, and ferric antioxidant power assay. It can be concluded that it is possible to extract good quality proteins from BSG and this by-product presents potential as a source for the extraction of a variety of proteins that might be of interest to the food industries.