Antioxidant Capacity of Lentil Flour Hydrolysates Obtained with Pancreatin

Abstract

Lentil is a valuable protein-rich crop, the health-promoting value of which can be further enhanced by its protein hydrolysis. In the present study, lentil flour was treated with pancreatin and the antioxidant capacity of the obtained hydrolysates with different degrees of hydrolysis (DH, 4-20%) was determined and compared with that of flour. The molecular weight (MW) distribution of the lentil proteins and their products of hydrolysis was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Size exclusion-high performance liquid chromatography (SE- -HPLC) was deployed to show the profile of low MW compounds of the hydrolysates. Additionally, total phenolic contents were determined with the Folin-Ciocalteu's phenol reagent. The hydrolysates had higher antiradical activity against DPPH , Trolox equivalent antioxidant capacity (TEAC) measured by the assay with ABTS +, ferric reducing antioxidant power (FRAP), and ability to bind Fe2+ compared to lentil flour. Between the hydrolysates, the highest DPPH scavenging activity (EC50 of 0.298 mg/mL), TEAC (98.6 μmol Trolox/g), FRAP (109.2 μmol Fe2+/g), antioxidant capacity of lipid-soluble compounds (ACL) determined by photoluminescence method (4.32 μmol Trolox/g), and Fe2+ chelating activity (80% at hydrolysate concentration of 0.3 mg/mL) were found for those with low DH (4-8%), which contained some subunits of proteins, polypeptides, and peptides with a wide MW range (0.556-66.0 kDa). The total phenolic content increased with increasing DH. In conclusion, the antioxidant capacity of lentil flour can be significantly improved by the limited hydrolysis of its proteins with pancreatin, as a result of the release of polypeptides and peptides with a wide range of MW. Thus modified lentil flour may be addressed and explored in future research as a functional food ingredient.