不同酚类与乳清蛋白共价交联对松仁油Pickering乳液的影响

Effects of Covalent Crosslinking of Different Phenols and Whey Proteinon Pine Nut Oil Pickering Emulsion

将没食子酸(GA)和香草酸(VA)分别与乳清蛋白(WPI)进行共价交联制备复合物(WGA和WVA),测定巯基含量、表面疏水性等理化指标并进行二、三级结构的表征。以复合颗粒为乳化剂制备松仁油Pickering乳液(WGAP和WVAP),对Pickering乳液的粒径分布、流变学行为和脂质氧化产物生成量等指标进行表征,研究不同剂量和类型的酚类物质诱导表面疏水性的变化对Pickering乳液理化特性和氧化稳定性的影响。结果表明,WGA和WVP的巯基含量降低,表面疏水性显著增加(P<0.05),WGA和WVA最大发射峰均红移到361.07 nm处,其中WGA的荧光强度猝灭率分别为91.05%,89.98%,94.02%,而WVA的荧光强度猝灭率分别为20.12%,27.49%,31.19%。与对照WPP相比,WGAP粒径分布的主峰位置集中于204.1~276.4 nm之间;WVAP粒径分布的主峰位置则集中于217.7~256.2 nm之间。WGAP和WVAP均属于假塑性流体,储能模量(G')始终高于损耗模量(G''),均表现出抑制脂质氧化产物生成的能力。2种羟基苯甲酸类可不同程度地提高表面疏水性,从而改善乳液的理化性能并减少脂质氧化过程中氧化产物的生成,具体表现为WGAP>WVAP。在一定剂量范围内,高添加量酚类化合物通过诱导蛋白质发生疏水性聚集或生成巯基-醌加成物两种方式提高了蛋白质的界面性能,从而使Pickering乳液粒径分布更均匀,体系趋向于稳定,脂质氧化程度更低。

In this research,two hydroxybenzoic acids,gallic acid(GA)and vanillic acid(VA),were covalently cross-linked with whey protein isolate(WPI)to prepare composite particles(WGA and WVA).The sulfhydryl content,surface hydrophobicity and other physical and chemical indicators of the particles were determined,and the secondary and tertiary structures were characterized.Pine nut oil Pickering emulsions(WGAP and WVAP)were prepared with particles as emulsifiers.Effects of the changes in the surface hydrophobicity of particles induced by two phenolic compounds with different structures and dose on the physicochemical properties and lipid oxidation capacity were evaluated.Pickering emulsion was characterized by the particle size distribution,rheological behavior and lipid oxidation products.The results showed that the sulfhydryl content of WGA and WVA was decreased,surface hydrophobicity was significantly increased(P<0.05);maximum emission peaks of WGA and WVA were both red-shifted to 361.07 nm.The fluorescence intensity quenching rates of WGA were 91.05%,89.98%and 94.02%,respectively,while the fluorescence intensity quenching rates of WVA were 20.12%,27.49%and 31.19%,respectively.Compared with control WPP,the main peak position of WGAP particle size distribution was concentrated between 204.1-276.4 nm;the main peak position of WVAP particle size distribution was concentrated between 217.7-256.2 nm.Both WGAP and WVAP were pseudoplastic fluids,the storage modulus(G')was always higher than the loss modulus(G''),and could inhibit the production of lipid oxidation products.Two hydroxybenzoic acids can increase the surface hydrophobicity to different degrees that improve the physical and chemical properties of the emulsion and reduce the generation of oxidation products in the process of lipid oxidation.The interfacial properties of proteins are improved by hydrophobic aggregation of proteins or the formation of thiol-quinone adducts,so that the particle size distribution of Pickering emulsions is more uniform,the system tends to be stable,and the degree of lipid oxidation is lower.