In this paper, the effects of peroxyl radical oxidation on the physicochemical and functional properties of walnut protein were investigated. Walnut protein isolate (WPI) containing 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) was oxidatively stressed under aerobic conditions in peroxyl radical-generating media. Incubation of walnut protein with increasing concentration of AAPH resulted in gradual carbonyl generation and free sulfhydryl group degradation. The results of surface hydrophobicity implied that oxidation leads to protein aggregation thus decreasing protein solubility in an AAPH concentration-dependent manner (P < 0.05). Emulsifying properties exhibited a significant increase (P < 0.05) at AAPH concentrations up to 0.2 mM and higher AAPH concentrations reduced the emulsifying capacity of WPI. These results indicate that appropriate oxidation is helpful to improve the emulsifying properties of protein, and with an increase of oxidation degree, emulsifying functional will damage.

中文翻译：

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过氧自由基诱导的氧化修饰对核桃蛋白理化和乳化性能的影响

本文研究了过氧自由基氧化对核桃蛋白理化和功能特性的影响。含有 2,2'-偶氮双（2-脒基丙烷）二盐酸盐（AAPH）的核桃分离蛋白（WPI）在有氧条件下在过氧自由基产生介质中受到氧化应激。随着 AAPH 浓度的增加，核桃蛋白的孵育导致逐渐产生羰基和游离巯基降解。表面疏水性的结果表明氧化导致蛋白质聚集，从而以 AAPH 浓度依赖性方式降低蛋白质溶解度（P  < 0.05）。乳化性能显着提高（P < 0.05) 在 AAPH 浓度高达 0.2 mM 和更高的 AAPH 浓度下会降低 WPI 的乳化能力。这些结果表明，适当的氧化有助于提高蛋白质的乳化性能，随着氧化程度的增加，乳化功能会受到损害。