Potential antioxidant peptides produced from whey hydrolysis with an immobilized aspartic protease from Salpichroa origanifolia fruits

- An AP from S. origanifolia fruits was immobilized on glutaraldehyde agarose support.
- The derivate presented high thermal stability and high reusability.
- Free and immobilized enzyme hydrolyzed WPC reaching similar DH after 20 h.
- Protein hydrolysis increased the antioxidant activity of the WPC.
- The shorter peptides had the strongest radical quenching effect.

An aspartic protease from Salpichroa origanifolia fruits was successfully immobilized onto an activated support of glutaraldehyde agarose. The immobilized enzyme presented higher thermal stability than the free enzyme from 40 °C to 50 °C and high reusability, retaining 54% of the initial activity after ten cycles of the process. Whey protein concentrates (WPC) were hydrolyzed with both free and immobilized enzyme, reaching a similar degree of hydrolysis of approximately 6-8% after 20 h. In addition, the immobilized derivate hydrolyzed α-lactalbumin protein with a higher affinity than β-lactoglobulin. The hydrolysate was ultra-filtrated, and the fractions were evaluated for antioxidant activities with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity method. The fraction containing peptides with a molecular mass below 3 kDa demonstrated a strong radical quenching effect (IC50: 0.48 mg/ml). These results suggest that hydrolyzed WPC could be considered as a promising source of natural food antioxidants for the development of functional food.