Date of Award

Summer 8-11-2017

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Food and Nutrition Sciences

Advisor

Balunkeswar Nayak

Second Committee Member

Dorothy Klimis-Zacas

Third Committee Member

Denise Skonberg

Additional Committee Members

Eric Gallandt

Vivian Wu

Soheila Maleki

Abstract

Shrimp is one of the major causes of adverse allergic reactions in both adults and children. Consumers with shrimp allergy have an immune system that is hypersensitive towards certain proteins in shrimp. The immune system of these consumers produces an antibody, immunoglobulin E (IgE), which binds to specific regions on these proteins and activates reactions leading to adverse symptoms. Most shrimp allergic consumers have IgE that binds to a shrimp myofibrillar protein known as tropomyosin. Other than avoidance of shrimp, structural modification of shrimp tropomyosin using food processing methods could influence the capacity of this allergenic protein to bind IgE. Thus, the objectives of this study were to evaluate the IgE binding capacity of tropomyosin extracted from whole shrimp following: 1) different methods of heat processing of shrimp, 2) exposure of shrimp muscle to high acid condition, 3) treatment with three microbial proteases, and 4) treatment with microbial and plant proteases.

In study 1, the IgE binding of tropomyosin remained unchanged following boiling, steaming, baking, microwave roasting, grilling and frying of whole shrimp in comparison with tropomyosin from raw shrimp. However, high pressure steaming significantly reduced IgE binding capacity especially at lower concentration of antigen. In study 2, treatment of whole shrimp with vinegar reduced the solubility of tropomyosin and thus the IgE binding capacity of tropomyosin in the soluble extract was reduced. However, immunochemical analysis of the insoluble protein fraction indicated retention of significant IgE binding by tropomyosin following exposure to vinegar. In study 3, after treatment of whole shrimp with three microbial proteases, an alkaline protease significantly reduced (> 80%) the IgE reactivity of tropomyosin. Treatment of whole shrimp with alkaline protease and two plant proteases in study 4 revealed that, the plant proteases did not significantly reduce the IgE reactivity of tropomyosin.

In summary, treatment of whole shrimp with enzymes that can cleave the IgE binding sites of tropomyosin could be the first step in the development of a hypoallergenic shrimp product. However, an in vivo assay like the cell mediator release assay is necessary to confirm the reduced immunoreactivity of tropomyosin following treatment with alkaline protease.

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