Abstract:To illustrate the high-value utilization of highland barley brewer’s spent grains, the process used to prepare its protease hydrolysate was optimized based on protein extraction from highland barley brewer’s spent grains using the DPPH free radical scavenging rate and reducing power as indicators. Thereafter, the in vitro antioxidant activity and cytoprotective effects of the hydrolysates were examined. The soluble and white highland barley brewer’s spent grains were found to be rich in protein, with protein contents of 31.46 g/100 g and 18.47 g/100 g, respectively. Using the ultrasound/cellulase-assisted alkali extraction and acid precipitation method, the protein extraction rates from the soluble and white highland barley brewer’s spent grains were 76.10% (m/m) and 29.88%, respectively. Alkaline protease was found to be most suitable for enzymatic hydrolysis of the proteins of soluble highland barley brewer’s grains. The optimal enzymatic hydrolysis conditions were as follows: solid to liquid ratio, 1:60 (m/V); ultrasonic treatment time, 15 min; enzyme dosage, 3.7% (m/m); and enzymatic hydrolysis time, 3.5 h. Under these conditions, the DPPH free radical scavenging rate of the protease hydrolysate of soluble highland barley brewer’s spent grains reached 95.02%. Different concentrations of the protease hydrolysate of soluble highland barley brewer’s spent grains did not exhibit negative effects on HepG2 cell viability. In addition, as the concentration of the protease hydrolysate of soluble highland barley brewer’s spent grains increased, ROS in cells damaged by H2O2 gradually decreased. In fact, 5.0 mg/mL (m/V) of the protease hydrolysate reduced ROS in damaged cells by approximately 50%. In addition to serving as a reference, this study provides a theoretical basis for preparing the protease hydrolysate of soluble highland barley brewer’s spent grains and illustrates its high-value utilization in healthy food and cosmetics.
