Study on effects of different thermal processings on immunocompetence of shrimp(Metapenaeus ensis) allergen

Shrimp proteins have been recognized as an important source of food allergens.The objective of this study was to analyze the immunocompetence and texture changes of shrimp allergen after different thermal processings.In this study,three heat methods were chosen to investigate their impacts on the immunocompetence of shrimp allergen,which included boiling,steaming,and autoclaving.After four different heating time,the total proteins and content of the major allergen were profiled by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE).The changes of immunocompetence of shrimp allergen were determined by Western-blotting and ELISA.In the meantime,texture profile analysis(TPA)was adopted to compare the quality changes of the processed shrimps.The results showed that the major allergen protein was still present in all of the total proteins of shrimps.Moreover,there was a new protein with molecular weight of 25-35 ku,which took on high immunocompetence.However,based on the results of Western-blotting and ELISA,the immunocompetence of the allergen protein was all reduced after the three thermal processings.In addition,different processings had different impact on the immunocompetence.Among the three methods,autoclaving had the best reducing effect towards immunocompetence of shrimp allergen.Cooking 5 min with autoclave could reduce 78% of the immunocompetence,while boiling and steaming for the same period could reduce 53% and 23% of the immunocompetence respectively.Moreover,when the autoclaving time was extended to 30 min,97% of the immunocompetence was lost.Nevertheless,the results of TPA showed that the quality of shrimp had been destroyed during the autoclaving.The rigidity and chewiness of the shrimp was greatly reduced after the autoclave processing.It is concluded that autoclave can greatly reduce the immunocompetence of shrimp major allergen protein at the expense of destroying the texture.The parameters of the autoclave are suggested to be optimized to reduce the immunocompetence and keep good texture and nutrition.