Effects Of Different Processing Methods On Antigenicity Of Ovalbumin In Hen’s Egg White

Hen’s egg is one of the cheap and balanced source of essential amino acids. However, itsstrong allergenicity has brought the potential egg allergy sufferers endless trouble. Because noefficient therapy currently exists for egg allergy, it is of great importance to study the effectsof different processing methods on the allergenicity of egg white. Based on which we canfurther find a best method of developing hypoallergenic egg product in the future.The aim of present work was to investigate the influence of several methods on thereduction of the ovalbumin (OVA) antigenicity in hen’s egg white so as to provide referenceof mitigating egg allergens. The paper mainly focused on the following aspects: preparingrabbit anti-OVA polyclonal antibodies for the later immunoassay; different proteases wereused to hydrolyzed the egg white to decrease the OVA antigenicity; effect of heat, ultrasoundand Autoclave treatment on the antigenicity of OVA in egg white were researched; combinedinfluence of physical treatments and proteolysis on the reduction of the OVA antigenicity inegg white were studied.The antiserum titer of1:1280000, with coating concentration of OVA of0.5μg/mL, wasdetermined by Enzyme-linked immunosorbent assay (ELISA). The crossreactivity of purifiedantibody of OVA to OVM measured by competitive indirect ELISA is near zero, whichrevealed that the prepared polyclonal antibodys are of great specificity.Five different enzymes, including Papain, Trpsin, Neutrase, Flavourzyme and AnimalProtein Hydrolyed Enzyme (APHE), were choosed for hydrolyzing the egg white after havingdetermined their optimal processing parameters by single factors experiment. SDS-PAGE,Immunoblot and competitive indirect ELISA showed that papain did better in the reduction ofOVA antigenicity among all five protease, with lowest antigen residual rate42.2%for Papain,70.5%for Trpsin,50.4%for Neutrase,72.1%for Flavourzyme,68.3%for APHE.When comes to heat, ultrasound and Autoclave treated egg white, SDS-PAGE andindirect elisa indicated that with temperature higher and processing time longer, the band ofOVA became broader and weaker for heat treated egg white, while the antigenicity of OVAincreased about30.4%under the condition of temperature100℃and time10min; althoughthere was no evident change in the band of OVA treated with ultrasound, the antigenicity ofOVA decreased the maximum of24.9%; Autoclave rendered significant change to themolecular weight distribution of OVA in egg white and the antigenicity of it can reduce themaximum of about25.9%.Papain was used to hydrolyze three physically pretreated egg whites, which includes eggwhite boiled in100℃water bath for10min; egg white treated with ultrasound of800W for30min; egg white treated with Autoclave for10min. Antigenicity of OVA in hydrolyzedpretreated egg white was analyzed by SDS-PAGE, Immunoblot and competitive indirectELISA. The results showed that ultrasound brought no further effect on OVA hydrolysis byPapain，with antigen residual rate48.7%；heat treatment and Autoclave improve the sensitivityof OVA to papain,with antigen residual rate12.4%and2.5%respectively。In conclusion, among all the methods of this paper tried, including enzymatic hydrolysis, ultrasound and Autoclave can decrease little but not much antigenicity of OVA in hen’s eggwhite, it seems that single treatment is not an ideal method of reducing antigenicity of OVA.Comparing the effect on OVA antigenicity of heat and Autoclave, we can find thatcollaboration processing is a promising method. And conbined treatment of Autoclave andPapain can reduce most antigenicity of OVA, which can provide the best reference of studyingegg allergy.