Production of antioxidant hydrolyzates from a lupinus mutabilis (Tarwi) protein concentrate with alcalase: Optimization by response surface methodology

Lupinus mutabilis (tarwi) is a cultivated legume used principally as a protein source in human and animal nutrition. In this study, protein concentrate was obtained from debittered and defatted tarwi seed flour. SDS-PAGE analysis revealed the presence of highly intense bands ranged between 35 and 60 kDa. Tarwi protein concentrate was subjected to the action of alcalase to produce hydrolyzates with antioxidant activity. A central composite design was employed to study the effect of the experimental variables, enzyme/substrate ratio and incubation time, on the degree of hydrolysis and the radical scavenging capacity. The influence of both variables on the variable responses was demonstrated. The optimal conditions to obtain the highest degree of hydrolysis were enzyme/substrate ratio of 1.72% and 133 min of incubation. The highest radical scavenging activity (TEAC value of 2.7 ± 0.1 μmol Trolox equivalents/mg protein and ORAC value of 3.8 ± 0.1 μmol Trolox equivalents/mg protein) was found in hydrolyzates with alcalase after 138 min and an enzyme/substrate ratio of 1.87%. Peptides released by the action of alcalase and containing hydrophobic and aromatic amino acids could contribute to the antioxidant effects observed. Tarwi proteins could be a new alternative as a food additive with antioxidant properties or as an ingredient of functional foods for health promotion and prevention of free radical-induced chronic diseases.