Antioxidant properties of Australian canola meal protein hydrolysates

Antioxidant activities of canola protein hydrolysates (CPHs) and peptide fractions prepared using five proteases and ultrafiltration membranes (1, 3, 5, and 10 kDa) were investigated. CPHs had similar and adequate quantities of essential amino acids. The effective concentration that scavenged 50% (EC50) of the ABTS+ was greatest for the <1 kDa pancreatin fraction at 10.1 μg/ml. CPHs and peptide fractions scavenged DPPH+ with most of the EC50 values being <1.0 mg/ml. Scavenging of superoxide radical was generally weak, except for the <1 kDa pepsin peptide fraction that had a value of 51%. All CPHs inhibited linoleic acid oxidation with greater efficiency observed for pepsin hydrolysates. The oxygen radical absorbance capacity of Alcalase, chymotrypsin and pepsin hydrolysates was found to be better than that of glutathione (GSH) (p < 0.05). These results show that CPHs have the potential to be used as bioactive ingredients in the formulation of functional foods against oxidative stress.