"DNA comet assay" – a validity assessment for the identification of radiation treatment of meats and seafood

Abstract

DNA comet assay was applied to detect radiation treatment of some fresh and frozen samples of meats and fresh seafood. Electrophoresis of irradiated cells caused stretching of the fragmented DNA in the gel in the form of a comet. The unirradiated and irradiated samples of meat (fresh and frozen lamb, beef and turkey) were clearly distinguishable on the basis of stained patterns of DNA in the form of round (or conical) intact cells or longer comets, respectively. One sample of seafood (salmon) could also be identified successfully as irradiated or unirradiated using comet assay. This discrimination was not possible with other samples of seafood, either due to the same kinds of migration patterns of DNA in both unirradiated and irradiated samples, or that the cells or nuclei could not be extracted, such as in squid and saithe samples. Validity of the comet test as a function of storage time was also studied, and in most of the cases the test was successful up to at least 6 days after irradiation. For most of the fresh or frozen meat samples investigated and for salmon, using suitable conditions, DNA comet assay can be applied as a rapid and inexpensive screening method for detection of irradiation treatment.