Shrimp allergy: Effect of vinegar soaking on allergenicity.

Background: Previous studies done have demonstrated that the muscle protein tropomyosin is the major shrimp allergen. This allergen, designated as Sa-II, capable of provoking IgE-mediated immediate hypersensitivity reactions after ingestion of cooked shrimp has been shown to be a 34-kDa protein containing 300 amino acid residues - rich in aspartic and glutamic acids. Studies have shown that this allergen is heat-stable. However, no studies have been done yet to demonstrate the effect of vinegar on this allergen. This study aims to demonstrate if vinegar soaking prior to cooking would have a significant effect on the allergenicity of shrimps, based on results of prick skin test. Methods: Eighteen shrimp-allergic and eighteen non-shrimp allergic pediatric patients were subjected to skin prick test using the conventionally-prepared shrimp exact. Mean wheal diameters obtained were compared to the mean wheal diameters obtained using the three experimental shrimp extracts prepared with preliminary vinegar soaking. For the adult group, 26 shrimp-allergic and 26 non-shrimp allergic patients were subjected to same skin prick test done for the pediatric patients. Results: The mean wheal diameters obtained using the shrimp extract prepared with preliminary vinegar soaking were significantly smaller than the mean wheal diameters obtained using the conventionally prepared shrimp extract. Wheal diameters obtained for the shrimp-allergic patients were significantly bigger than wheal diameters obtained for the control non-shrimp-allergic individuals. Results were similar for both pediatric and adult patients. Conclusion: The results indicate that vinegar soaking prior to cooking can reduce the allergenicity of shrimps. However, further confirmation/validation of these results using double-blind placebo-controlled food challenges would be ideal if resources would permit. (Author)