Epitope mapping and the effects of various factors on the immunoreactivity of main allergens in egg white

Egg white has high protein content and numerous biological/functional properties. However, the reported allergenicity for some of the proteins in the egg white is an issue that needs to be paid exclusive attention. A consideration on the structure of the IgE epitopes and their sequences as well as a comprehensive understanding of the effects of various processes on the epitopes and the impact of the gastrointestinal tract on them can help target such issues. The current study focuses on the identified IgE epitopes in the egg white proteins and evaluates the effects of gastrointestinal digestion, carbohydrate moiety, food matrix, microbial fermentation, recombinant allergen, heat treatment, Maillard reaction and combination of the various processes and gastrointestinal digestion on the egg white allergenicity. Although the gastrointestinal tract reduces the immunoreactivity of native egg white proteins, some of the IgE epitope-containing fragments remain intact during the digestion process. It has been found that the gastrointestinal tract can have both positive and negative impacts on the IgE binding activities of egg white proteins. Elimination of the carbohydrate moiety leads to a reduction in the immunoreactivity of ovalbumin. But, such effects from the carbohydrate parts in the IgE binding activity needs to be explored further. In addition, the interaction between the egg white proteins and the food matrix leads to various effects from gastrointestinal tract on the digestion of egg white proteins and their subsequent immunoreactivity. Further on this matter, studies have shown that both microbial fermentation and Maillard reaction can reduce the IgE binding activities of egg white proteins. Also, as an alternate approach, thermal process can be used to treat the egg white proteins which may result in the reduction or increase in their IgE binding activities depending on the conditions used in the process. Overall, based on the reported data, the allergenicity levels of egg white proteins can be mitigated or escalated depending on the conditions applied in the processing of the food products containing the egg white. So far, no practical solutions have been reported to eliminate such allergenicity.