An Investigation on the Effects of Hydrolysis Conditions on the Extraction of Antioxidant Peptides from Peanuts

The use of protein hydrolysate containing antioxidant peptides in the formulation of functional food has been increasing recently. The types and sequences of amino acids, the type of hydrolyzing enzymes and hydrolysis progress have some important impacts on the properties of protein hydrolysate.

In this research, the effects of pepsin and alcalase enzymes (E/S:1/10) under optimal conditions of each ones, were investigated on the extraction of antioxidant peptides from peanuts protein. Peanut’s oil was extracted using solvent extraction method and protein was precipitated at isoelectric point. The extracted protein was subjected to the pepsin and alcalase enzymes for maximum period of five hours. The progress of hydrolysis was considered every thirty-minutes using Ortho-Phthalaldehyde (OPA) method.

The results indicated that the most hydrolysis occurs after 250 and 90 min of hydrolysis for pepsin and alcalase, respectively and the values of free amino acid groups increased from 167.0 to 263.0 μM leucin/mg protein (for alcalase) and from 415.0 to 517.0 μM leucin/mg protein (for pepsin). Moreover, the antioxidant activity of protein hydrolysate was investigated based on DPPH and ABTS radical scavenging activity. By increasing the degree of hydrolysis, the DPPH and ABTS radical scavenging activity increased simultaneously. The maximum values of DPPH and ABTS free radicals scavenging activity were measured respectively, 5175.0 and 756.0 mMTE/mg proteins (for pepsin) and 3644.0 and 1087.0 mMTE/mg proteins (for alcalase).

The results indicated that the progress of enzymatic hydrolysis of peanut protein by alcalase and pepsin enzymes leads to producing more antioxidant peptides and the final products obtained can be considered as a candidate for producing functional foods.