The identification of fish becomes more difficult once it has been processed and morphological characteristics are no longer visible. Methods determining differences in protein have been used for identification; when water-soluble proteins of muscle tissues are separated by electrophoresis, isoelectric focussing or by liquid chromatography, unique species profiles can be obtained. These methods are not as reliable when used on highly processed food products as the proteins become denatured. In terms of simplicity and speed antibody based methods would be most appropriate. However only a limited number of immunoassays have been developed and none are available for wide scale commercial use.
DNA based methods have therefore become the most appropriate approach to species identification as DNA remains detectable in all but the most heavily processed samples. Species identification is achieved by detection of differences in sequence between fish.
The project will address improvements in fish species identification by simplifying an existing DNA screening method. The new method will employ a chip-based capillary electrophoresis (CE) system to analyse different DNA fingerprints produced by enzymatic cleavage of polymerase chain reaction (PCR) generated fragments. The CE system can rapidly detect, size and quantify multiple DNA fragments. The CE endpoint system will be applied to an existing method for the identification of salmon species. A further method will be developed for a number of white fish species. This method will be taken through to a validation study performed on products by a number of different laboratories. The chip-based CE system is relatively cheap, easy to use and provides reliable results. This will make the assays developed on it suitable for wide use in analytical laboratories.
<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.