Interaction Of Four Egg White Proteins And Their Effects On The Quality And Allergenicity Of Egg White Proteins

In recent years,with the development of healthy,green and safe consumption concept,liquid egg has become a development trend of egg industry.However,limited information is available on whether the proteins in liquid egg interact with each other during the productive process,and whether these interactions affect the quality and allergenicity of egg white proteins,which remains to be further studied.Therefore,in this thesis,the interaction among the main proteins in egg white and their effect on the physical properties,structure and allergenicity of egg white proteins,as well as on the quality of liquid egg white under pasteurization temperature were studied.The results would provide theoretical basis for improving the value of egg white and has important theoretical value for the further processing of egg products and the quality of processed products.The main methods,results and conclusions are as follows.1.Heat treatment was carried out at 25,60,65 and 70℃ for the mixture and monomer of ovalbumin,ovotransferrin,lysozyme and ovomucoid.Molecular weight of protein was characterized by reduced and non-reduced SDS-PAGE.The physical properties of single and mixed proteins were analyzed by turbidity and solubility.The solubilities of OVA-Lys,OVT-Lys and OVA-OVM were decreased and the turbidity of them were increased due to the interactions heated at 70℃.The solubility of OVT-OVM and OVM-Lys were decreased and the turbidity of them were increased at 65℃ and 70℃.2.The changes of the tertiary structure,secondary structure and hydrophobicity of single and mixed proteins were analyzed using ultraviolet-visible spectroscopy,circular dichroism spectroscopy,exogenous fluorescence spectroscopy.OVA-Lys interacted at 70℃,which exposed the hydrophobic groups.OVA-OVM collapsed through hydrophobic interaction after the exposure of hydrophobic groups at 65℃ and 70℃.OVT-OVM collapsed through hydrophobic interaction after the exposure of hydrophobic groups at 60℃,65℃and 70℃.The interaction between OVT-Lys and OVM-Lys occurred after heating at 65 and 70℃,which caused the structure unfolded and the hydrophobic groups exposed.3.The IgG-binding ability and IgE-binding ability of single and mixed proteins after interaction were analyzed using competitive ELISA.It was found that the IgG and IgE binding ability of OVA-OVT were not affected by interaction.The interaction between OVA-Lys and OVT-Lys at 70℃ could reduce the IgG and IgE binding ability of each other.The IgG-binding ability of OVA and OVM were increased after interaction at 65 and 70℃,and the IgE binding ability of OVA was decreased by the interaction at 70℃and the IgE binding ability of OVM was decreased by heating at 60,65 and 70℃.The IgG binding ability of OVT was improved by the interaction of OVT-OVM at 60,65 and 70℃,and the IgE binding ability of OVT was decreased by the interaction of OVT-OVM at 70℃.The IgG and IgE binding ability of OVM were increased by the interaction of OVT-OVM at 70℃.OVM-Lys interaction at 70℃ could improve the IgG and IgE binding ability of Lys and OVM.4.To evaluate the effect of interaction on the allergenicity of OVA and OVM,cytokines released by activated basophilic cells were detected.The releases of TNF-α and IL-4 of activated basophilic cells sensitized by OVA as well as the releases of histamine of activated basophilic cells sensitized by OVM were significantly decreased after heating at 70℃.The releases of IL-6 of activated basophilic cells sensitized by OVM were significantly decreased after heating at 60,65 and 70℃.The releases of histamine and TNF-α of activated basophilic cells sensitized by OVA-OVM were significantly decreased at 65 and 70℃,and the releases of IL-4,IL-6 and β-HEX were significantly decreased by interaction at 70℃.5.To study the effect of protein interaction on the functional properties of egg white,the pH,viscosity,emulsifying and foaming properties of egg white treated under pasteurized temperatures were tested.The turbidity of egg white was significantly increased at 70℃,and the viscosity was increased with the increase of temperature.The foamability and foam stability were significantly decreased at 65 and 70 ℃.The emulsifying property and emulsion stability were significantly increased at 60℃,and significantly decreased at 70℃.