Shrimp tropomyosin retains antibody reactivity after exposure to acidic conditions

Authors: ADESEYE, LASEKAN - University Of Maine; CAO, HANJUAN - University Of Maine; Maleki, Soheila; NAYAK, BALUNKESWAR - University Of Maine

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2017
Publication Date: 1/19/2017
Citation: Adeseye, L.O., Cao, H., Maleki, S.J., Nayak, B. 2017. Shrimp tropomyosin retains antibody reactivity after exposure to acidic conditions. Journal of the Science of Food and Agriculture. https://doi:10.1002/jsfa.8221.
DOI: https://doi.org/10.1002/jsfa.8221

Interpretive Summary: Although shrimp can be found in certain high acid food matrices, the allergenic capacity of a shrimp allergic protein, tropomyosin, exposed to low pH condition has not been fully clarified. Thus, a model marinade comprising white vinegar adjusted to different pH was used to determine the effects of acid-treatment on the immunoreactivity of tropomyosin. Whole shrimp experienced either swelling or shrinkage after marination in acid depending on the vinegar pH and the final muscle pH. The extractability of soluble shrimp proteins was reduced significantly among shrimp marinated in vinegar at pH 1.0–3.5, and a substantial amount of tropomyosin was retained in the insoluble material. Consequently, the immunoglobulin E (IgE, the allergic antibody) binding capacity of tropomyosin was significantly lower in the soluble protein fraction of shrimp marinated at pH1.0–3.5 compared with samples marinated at pH4.8 and control. However, tropomyosin in the insoluble protein fraction of all marinated shrimp showed strong IgE-binding capacity at all marinating conditions. Thus, tropomyosin in shrimp exposed to low pH condition retained its allergenic capacity. Analysis of the insoluble protein fraction was crucial for the accurate determination of the effect of low pH condition on the immunoreactivity of this allergen.

Technical Abstract: Although shrimp can be found in certain high acid food matrices, the allergenic capacity of shrimp tropomyosin exposed to low pH condition has not been fully clarified. Thus, a model marinade comprising white vinegar adjusted to different pH was used to determine the effects of acid-induced denaturation on the immunoreactivity of tropomyosin. Whole shrimp experienced either swelling or shrinkage after marination depending on the vinegar pH and the final muscle pH. The extractability of soluble myofibrillar proteins was reduced significantly among shrimp marinated in vinegar at pH 1.0–3.5, and a substantial amount of tropomyosin was retained in the insoluble pellets. Consequently, the immunoglobulin E (IgE)-binding capacity of tropomyosin was significantly lower in the soluble protein fraction of shrimp marinated at pH1.0–3.5 compared with samples marinated at pH4.8 and control. However, tropomyosin in the insoluble protein fraction of all marinated shrimp showed strong IgE-binding capacity at all marinating conditions. Thus, tropomyosin in shrimp exposed to low pH condition retained its allergenic capacity owing to the conservation of its linear epitopes. Analysis of the insoluble protein fraction was crucial for the accurate determination of the effect of low pH condition on the immunoreactivity of this allergen.