Technofunctional properties of a brewers' spent grain protein-enriched isolate and its associated enzymatic hydrolysates

The Nitrogen solubility, turbidity, emulsion and foaming properties, and the heat stability of a brewers' spent grain protein-enriched isolate (BSG-PI) was studied between pH 2.0-12.0. The effect of enzymatic hydrolysis using Alcalase, Corolase PP, Flavourzyme and Promod 144MG on these properties was also determined. BSG-PI demonstrated low solubility below pH 6.0, however, hydrolysis with all enzymes significantly increased BSG-PI solubility between pH 2.0-12.0. Flavourzyme, Corolase PP and Promod 144MG hydrolysates displayed an improved emulsion activity index (EAI) with an EAI of 466.69 m²g^-1 obtained for the Flavourzyme hydrolysates at pH 9.0. Improved foam expansion (FE) was observed above pH 9.0 in all samples while hydrolysis significantly reduced foam drainage stability (FS) of BSG-PI. BSG-PI was highly heat stable at 140 °C above pH 6.0 even after >300 min heating. Hydrolysis of BSG-PI resulted in increased turbidity when aqueous suspensions were stored overnight at 4 or 20 °C. The results demonstrate the potential of the alkaline extracted BSG-PI and its associated hydrolysates as a cereal derived source of technofunctional ingredients for the food industry.