Production of lentil-based functional ingredients for cardiovascular health by high pressure-assisted proteolysis

Abstract

Bioactive peptides generated from food proteins are eminent ingredients for functional foods that claim benefits for cardiovascular health. Amongst several approaches to release these peptides, hydrolysis of food proteins with proteolytic enzymes is a promising choice. Enzyme treatment of proteins during high hydrostatic pressure (HHP) treatments considerably enhances their hydrolysis (Chicon et al., 2006). The conformational state of the protein under high pressure determines the behaviour of proteinases specific for hydrophobic/aromatic residues buried in the hydrophobic core of the native protein. This work investigated the potential of HHP to produce hydrolysates from lentil proteins that combine angiotensin I converting enzyme (ACE)-inhibitory and antioxidant activity for cardiovascular health. Lentil protein extracts were hydrolysed with Protamex® (Novozymes) at 100, 200, 300 and 400 MPa for 15 min. ACE inhibition of lentil hydrolysates was determined by fluorescence (Santandreu and Toldra, 2006) in the fractions < 3 kDa obtained after ultrafiltration at a dose of 0.15 mg/mL. SDS-PAGE was carried out. Antioxidant activity of lentil hydrolysates was determined by the oxygen radical absorbance assay (Davalos et al. 2003). Lentil proteolysis by Protamex® was significantly enhanced with HHP compared to atmospheric pressure. Pressure of 300 MPa led to a significantly higher proteolysis than pressures of 100, 200 and 400 MPa. Treatment of lentil protein extracts with Protamex® under high pressure up to 300 MPa produced hydrolysates in which lentil globulins were totally hydrolysed to peptides < 20 kDa. ACE-inhibitory activity of lentil hydrolysates increased as function of pressure up to 300 MPa. The hydrolysates obtained with Protamex® at 300 MPa showed the highest ACE-inhibitory activity (89% ACE inhibition). Antioxidant activity of lentil hydrolysates was improved with HHP-assisted proteolysis treatment up to 200 MPa compared to atmospheric pressure. HHP treatments of 300 and 400 MPa did not increase the antioxidant capacity of lentil hydrolysates. These results suggest that HHP enhances proteolysis of lentil globulins by Protamex® which produces peptides with ACE-inhibitory and antioxidant activity that could be applied as functional ingredients for cardiovascular health.