Antioxidative Activities and Peptide Compositions of Corn Protein Hydrolysates Pretreated by Different Ultrasonic Methods

Abstract

Three different ultrasonic methods were compared based on the production of antioxidative peptides from corn protein. The corn protein was sonicated with probe ultrasound (PU), flat plate ultrasound with sweeping frequency , and flat plate ultrasound with fixed frequency before hydrolysis by acalase. Degree of hydrolysis (DH), antioxidative activities and peptide compositions were determined. The hydrolysates derived from PU pretreatment yielded the highest DH. However, lower Fe2+-chelating activity, 1,1-diphenyl-2-picrylhydrazyl radical and hydroxyl radical scavenging activities were observed for the corn protein hydrolysates (CPH) under PU pretreatment. The percentage of peptides with molecular weight of 500–180 Da increased with the increasing of DH. While the order of percentage of MW 2000–500 Da relative to ultrasonic method was in accord with Fe2+-chelating activity and OH radical scavenging activity. Amino acid analysis indicated that CPH under FPUSF and FPUFF pretreatments, with higher hydrophobic amino acid contents, had stronger antioxidative activities.