Studies on the Proximate, Functional and Antioxidant Properties of Fermented and Unfermented Kariya (Hildergardia barterii) Seed Protein Hydrolysates Obtained by Enzymatic Hydrolysis

Abstract

The degree of hydrolysis (DH), proximate composition, functional properties and anti-oxidative characteristics of enzymatic kariya seed hydrolysates were evaluated with a view to increasing the utilisation of the seed as food ingredient. Protein hydrolysates were obtained from fermented and unfermented kariya seed protein isolate using two proteolytic enzymes: Pepsin and pancreatin to obtain fermented pancreatin kariya protein hydrolysate (FPcKPH), unfermented pancreatin kariya protein hydrolysate (UPcKPH), fermented pepsin kariya protein hydrolysate (FPsKPH) and unfermented pepsin kariya protein hydrolysate (UPsKPH). The results showed that pancreatin hydrolysates had higher degree of hydrolysis (FPcKPH; 65.20% and UPcKPH; 50.50%) than pepsin hydrolysates (FPsKPH; 53.00% and UPsKPH; 33.93%) while the fermented hydrolysates showed higher DH than the unfermented hydrolysates both in the pancreatin and pepsin hydrolysates. The results also showed that fermented hydrolysates had better functional properties than the unfermented samples. The protein contents of the fermented hydrolysates were also improved. The antioxidant characteristics showed that fermented kariya protein hydrolysates exhibited higher DPPH (2,2-diphenyl-2-picrylhydrazyl hydrate) radical scavenging activity (FPcKPH, IC501.03; FPsKPH, IC501.40; UPcKPH, IC50 1.51; UPsKPH, IC50 6.97 mg extract/ml), metal chelating (FPcKPH, IC50 0.95; FPsKPH, IC500.53; UPcKPH, IC50 1.27; UPsKPH, IC50 1.06 mg extract/ml) and ferric reducing antioxidant power (FPcKPH, 0.63; FPsKPH,0.50; UPcKPH 0.35; UPsKPH, 0.23 AAµg/g). The study concluded that fermented kariya seeds hydrolysates could find applications as potential source of natural anti-oxidants in food.