Effects of different oxidation methods on the functional properties and gel characteristics of hazelnut proteins

Abstract This study aimed to investigate the effects of different oxidation modes on the functional and gel properties of hazelnut proteins. The solubility of hazelnut protein showed a small trend when the oxidation level was low, and it decreased significantly with the increase in concentration. The maximum value of water-holding capacity (WHC), emulsifying activity index (EAI), and emulsion stability index (ESI) was 343.33%, 56.00 m2 g−1, and 75.85 min at AAPH concentration of 1.0 mmol L−1, respectively. The functional properties of hazelnut proteins, except oil-holding capacity (OHC), gradually reduced with the increase in malondialdehyde (MDA) concentration. H2O2 modified improved OHC, foaming capacity, foam stability, and EAI of hazelnut proteins, whereas WHC and ESI gradually decreased. The results of the secondary structure of hazelnut protein gels indicated a high ratio of α-helix and β-fold of the gels. Also, the increase in oxidation led to an increase in the gels' voids. Also, oxidation led to a rough and loose network structure of hazelnut protein gels. These results suggested that peroxyl radical, hydroxyl radical, and MDA produced during lipid peroxidation affected the interfacial properties of hazelnut protein and disrupted the formation of hazelnut protein gel, thus affecting the quality of hazelnut protein.