Changes in the allergenicity during different preparations of pomfret, hilsa, bhetki and mackerel fish as illustrated by enzyme-linked immunosorbent assay and immunoblotting

Background: Although the identification and characterization of several fish allergens have already been reported, there is almost no data on Indian fish allergens and the effect of thermal processing on their allergenicity. This study aimed at the evaluation of the changes in the level of allergenicity of 4 highly consumed Indian fishes, i.e. pomfret, hilsa, bhetki and mackerel, that occurred after boiling and frying. Methods: In this study 110 patients with fish hypersensitivity as evidenced by clinical history and symptoms were recruited based on their positive skin prick test results. The raw, boiled and fried muscle extracts of the 4 fishes were prepared, and each extract was tested by ELISA and immunoblotting with patients' sera. Results: ELISA and immunoblotting studies demonstrated that the raw muscle extracts of pomfret, hilsa, bhetki and mackerel were allergenic. While the allergenicity of boiled and fried extracts of pomfret and hilsa was considerably reduced, maximum allergenicity of bhetki was demonstrated in the fried extract. The degree of allergenicity of bhetki was demonstrated in the order fried > boiled > raw while that of mackerel followed the order raw > boiled similar or equal to fried. Conclusion: The specific IgE-binding activity and immunoblot profile clearly showed that pomfret and hilsa fish allergens are heat-labile, while allergens of bhetki and mackerel maintained strong reactivity even after thermal treatment. Copyright (c) 2006 S. Karger AG, Basel.