Metal chelating and radical scavenging activities of soybean protein hydrolysates for lipid oxidation inhibition: A cross-varietal experimental and bioinformatic approach.

Abstract

This study examined how soybean variety influences peptide composition, antioxidant activities, and lipid oxidation inhibition in soy protein hydrolysates (SPH). Protein isolates from eight varieties (SP1-SP8) were hydrolyzed with Alcalase (2% E/S, 2 h), yielding degrees of hydrolysis of 9.68-12.22% and peptide concentrations of 1.07-1.27 mmol NH₂/g. Size-exclusion chromatography and LC-MS/MS revealed distinct peptide and molecular-weight profiles, with SP1 and SP4 enriched in the 300-1000 Da. In silico analysis using AnOxPePred selected 20 peptides, among which His-Phe showed the highest predicted free radical-scavenging (0.488) and metal-chelating (0.311) potentials. SP1 and SP4 were enriched in His-Phe and Arg-Phe and displayed superior performance, including stronger DPPH scavenging, Cu2+ chelation, and inhibition of lipid oxidation. By contrast, SP6 exhibited pronounced Fe2+ chelation but comparatively weak overall antioxidant efficacy. The findings demonstrate that varietal selection can markedly modulate the lipid oxidation-mitigating properties of SPH.