Evaluation of the technological functional properties and antioxidant activity of protein hydrolysate obtained from brewers' spent grain

Beer production generates a large amount of waste, called brewers' spent grain (BSG), which has a nutritional potential mainly as a protein source. Proteins can be modified by hydrolysis releasing peptides with different bioactivities, such as antioxidant activity. The aim of this study was to produce a protein hydrolysate from protein concentrate obtained from BSG, evaluating its functional properties and antioxidant activity. The BSG protein concentrate was obtained by changing the pH at the isoelectric point, established at 3.5. The concentrate was hydrolyzed with the enzyme Alcalase, after defining the enzyme: substrate ratio (2:100), and 4 h was hydrolysis time (hydrolysis degree 32%). The hydrolysate showed better results of antioxidant activity than the concentrate in all tested methods, highlighting the ABTS radical capture with activity above 90%. The foaming capacity was not significantly modified (49%–45%), while emulsion capacity was significantly improved (30%–72%) by the hydrolysis process. Practical applications The results of this work indicate that some functional properties of BSG can be upgraded by enzymatic hydrolysis. These BSG hydrolysates showing improved antioxidant and emulsifying activities can be useful ingredients in food formulations adding value to this important byproduct of the beer industry.