In vitro α-glucosidase, angiotensin converting enzyme and dipeptidyl peptidase-IV inhibitory properties of brewers' spent grain protein hydrolysates

- A tryptic digest of BSG protein resulted in highest α-glucosidase inhibition.
- BSG protein hydrolysates were poor inhibitors of α-amylase.
- Hydrolysis of BSG protein significantly increased DPP-IV inhibition.
- BSG protein hydrolysates demonstrated potent ACE inhibitory activity.

The in vitro α-glucosidase, α-amylase, dipeptidyl peptidase IV (DPP-IV) and angiotensin converting enzyme (ACE) inhibitory activities of pale brewers' spent grain protein enriched isolate (BSG-PI) hydrolysates were studied. Eleven commercially available enzyme preparations derived from papaya, porcine pancreas, Aspergillus oryzae and Bacillus licheniformis were used to generate the hydrolysates. The hydrolysates had degree hydrolysis (DH) values ranging from 1.15 to 14.67% and the DH values obtained correlated well with hydrolysate molecular mass distribution profiles. Reverse-phase HPLC analysis of the BSG-PI and its hydrolysates demonstrated considerable variation in peptide composition. While tryptic digests of BSG-PI resulted in the greatest α-glucosidase inhibitory activity, no significant change in α-amylase inhibition was observed with the hydrolysates. Digestion with Corolase PP resulted in the highest DPP-IV inhibition (75 ± 3.06% at 3.5 mg mL− 1) while the Prolyve 1000 hydrolysate displayed highest ACE inhibition (89.25 ± 2.46% at 1 mg mL− 1). The results obtained highlight the potential role of the BSG-PI hydrolysates as functional food ingredients in the management of type II diabetes and hypertension.