The effects of free radicals and metal ion on milk protein β‐lactoglobulin (BLG) glyco‐oxidation

Abstract

SummaryIn this study, the effects of H2O2, 2,2′‐Azobis(2‐amidinopropane) dihydrochloride (AAPH) and metal ion Fe3+ on β‐lactoglobulin (BLG) glyco‐oxidation were investigated. The results demonstrated all the three inducers caused BLG morphology change and higher molecular weight BLG‐glucose (BLG‐Glu) adducts formation. H2O2 and AAPH significantly accelerated BLG oxidation by increasing carbonyl content and decreasing freesulphydryls (P < 0.05). However, Fe3+ showed little influence on carbonyl and free sulphydryls contents. All the three inducers promoted fluorescent‐advanced glycation end products (fl‐AGEs) and carboxymethyl‐lysine (CML) formation. Fe3+ and H2O2 (0.5% and 1%) could increase methylglyoxal (MGO) level and caused less time to reach its peak concentration than control group. Compared with the control group, new glycation sites were determined in H2O2, AAPH and Fe3+ treatments, indicating the inductive effect of those free radicals or metal ion on BLG glycation. The results will provide important information for the control of protein‐based products glyco‐oxidation during food processing and storage.