pH偏移处理对猪肝蛋白乳化特性的影响

Effect of pH-Shifting Treatment on the Emulsification Characteristic of Porcine Liver Protein

为探究猪肝蛋白(porcine liver protein,PLP)的pH偏移诱导重折叠改性方法与机制。猪肝蛋白溶液经pH偏移处理(pH3~11)后再将pH值调整到中性,经过冻干处理后再测定改性猪肝蛋白的溶解度、乳化活性与稳定性、表面疏水性、乳液粒径与Zeta电位、活性巯基及内源荧光光谱、红外光谱。结果表明,在pH酸性偏移条件下,PLP的溶解度、乳化活性及乳化稳定性均有所下降,乳液粒径增大、Zeta电位绝对值下降,而pH碱性偏移处理会使PLP的溶解度和乳化活性、乳化稳定性提高,乳液粒径减小、Zeta电位绝对值上升;改性后PLP的荧光强度及活性巯基含量降低,表明pH偏移处理对蛋白质三级结构产生显著影响,而根据红外光谱结果显示,其对蛋白质二级结构影响较小。因此,pH碱性偏移处理可作为提高猪肝蛋白的乳化性、溶解性等功能特性的有效手段。

To explore the method and mechanism of pH-shifting-induced refolding modification of the porcine liver protein(PLP),and to lay the theoretical foundation for the high-value development and utilization of por-cine liver.The solution of porcine liver protein was treated with pH-shifting(pH3-11)and then adjusted to neu-tral.After lyophilization,the solubility,emulsification activity,emulsion stability,surface hydrophobicity,emul-sion size,Zeta potential,active sulfhydryl groups,endogenous fluorescence spectra,and infrared spectra of the modified porcine liver protein were measured.The results showed that the solubility,emulsification activity,and emulsion stability of PLP decreased after acidic pH-shifting treatment,the emulsion particle size increased and the absolute value of Zeta potential decreased,while the alkaline pH-shifting treatment increased the solu-bility and emulsification activity and emulsion stability of PLP,and the emulsion particle size decreased and the absolute value of Zeta potential increased.The fluorescence intensity and active sulfhydryl content of PLP decreased after modification,indicating that the pH-shifting treatment had a significant effect on the tertiary structure,while the infrared spectroscopy results showed that it had less effect on the secondary structure.The alkaline pH-shifting treatment can effectively improve the functional properties of porcine liver protein such as emulsification and solubility.