Research On Ovalbumin Cross-linkage By Polyphenol Oxidase And Pilot Production Design Of Cross-linked Production

Egg allergy is a major problem for human food safety.No egg or its ingredients diets are the best way to prevent egg allergy at present.However,it is too hard for these patients to have no egg dishes.The ovalbumin?OVA?comprising 54%of total egg white proteinhas been regarded as the major allergen in egg white protein.Decreasing the OVA content in egg proteins may be a good way to reduce egg allergy.In this thesis,The OVA was catalyzed to cross-linking by the polyphenol oxidase.And some characteristics of cross-linked OVA,including the changes of OVA structure,in-vitro digestion and allergenicity and so on,were evaluated.The major methods and results were as follows.1.OVA in fresh egg white was purified by column chromatography and detected by SDS-PAGE.The purity of OVA was suitable for following studies.And the approach was simple and the good repeatability.2.The optimum parameters for polyphenol oxidase catalyzed cross-linking of OVA were established,at 50?for 8h,and phosphate buffer 50mM,polyphenol oxidase of 1000U/mL,ovalbumin 1mg/mL,and caffeic acid of and 1mmol/L,respectively.The all liquid total volume was 1.5mL together.3.The structure of cross-linked OVA was analyzed by the Far-UV CD spectrum,the fluorescence intensity spectra,the UV absorption spectra and dynamic light scattering?DLS?,respectively.The cross-linked OVA showed a higher hydrophobicity and a more loosely structure than native OVA.4.The digestibility of the cross-linked OVA was assessed by simulated gastric fluid?SGF?and simulated intestinal fluid?SIF?.It shown that OVA and cross-linked OVA were both easyily digested in SIF,but were not digested in SCF.5.The capacity of cross-linked OVA binding IgG and IgE was lower than native OVA.The allergenicity of OVA could decrease by cross-linking with caffeic acid catalyzed by polyphenol oxidase.6.Comparing with the native OVA groups,the levels of specific IgE,IgG₁,IgG_2aa and IgG and the histamine content in mice sera of cross-linked group were all lower.Meanwhile,the level of mMCP-1,IL-4,IL-5 and IL-13 secreted by mice spleen cells were all significantly lower as well.The cross-linking OVA by polyphenol oxidase could greatly decrease the allergencity of egg in some degree.7.The pilot scale for cross-linked OVA was achieved based on the the lab-scale works,the technical routine for pilot scale was designed,the facilities were selected and the diagram was drawn.