Use of immunological techniques for detecting species substitution in raw and smoked fish

 Immunological techniques based on double immunodiffusion and immunodotting have been designed to detect the substitution of halibut (Hippoglossus hippoglossus) for sole (Solea solea) fillets. An immunodotting technique has been also developed to differentiate between smoked cod (Gadus morhua) and smoked eel (Anguilla anguilla) fillets. Antisera raised against water-soluble extracts of raw halibut and smoked cod were employed. Antiserum to cod proteins did not show cross-reaction with eel proteins, whereas antiserum to halibut proteins cross-reacted with sole proteins. Species-specific antiserum to halibut proteins was achieved by adsorption on a polymer of sole proteins. These methods are very easy to perform and provide the basis for the development of rapid tests for detecting species substitution in fish products. Received: 18 April 1996/Revised version: 5 July 1996