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Listen to this siteThursday 28 August 2003
These research projects aim to develop a method that can identify the type of white fish in fish products and determine the quantity present.
Study Duration : April 2001 to January 2003
Contractor : Central Science Laboratory and Rowett Research Services
The Food Labelling Regulations requires a quantitative declaration to be made for ingredients which are mentioned in the name of the food. In fish products, the amount of a named species can be given. There are, however, currently no established methods which can address authentication issue for the white fish (cod and haddock). This project is the first attempt to provide an assay which will be able to not only identify the cod and haddock species but to quantify that species in complex food products using DNA.
Project Q01051/61 uses the same premise as the current nitrogen factor assay for fish determination, in that, there is a constant relationship between nitrogen and the weight of fish tissue.
This new assay is based on the relationship between gene copy number and the weight of fish tissue.
Unlike the nitrogen factor assay however, this DNA based method will be applicable to complex and processed foods.
Therefore, the first phase of the project will be designed to determine the relationship between tissue weight and gene copy number for cod (
Gadus morhua
) and haddock (
Melanogrammus aeglefinus
).
A set of Taqman primers and probes will be designed to genomic DNA and used to compare intra- and inter-fish and inter season gene copy number.
In the event of large seasonal or morphological differences the study will be terminated.
If there is only a small variation the second phase of the project will be to develop an assay based on the use of immobilised probes, complementary to microsatellite genes of either cod or haddock.
When DNA correctly hybridises to the probe it will form double stranded DNA which will be measured using double stranded DNA antibodies in an ELISA format.
The quantity of fish flesh will be determined from a standard curve of known weights of tissue.
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