DNA comet assay and changes in microflora load as screening methods to detect irradiated food in Egypt

الملخص EN

In the present study the microgel electrophoresis of single cells (DNA Comet Assay), and changes in microflora load were applied to detect irradiation treatment of strawberries and fresh-deboned chicken produced in Egypt.

Strawberry samples were irradiated at 1.0, 2.0, 3.0 and 4.0 kGy, stored at 4oC±1 and analyzed at 0 and 7 days post.-irradiation.

Fresh- deboned chicken meat samples were exposed to 2.0, 3.0, 4.0 and 5.0 kGy, stored at 4oC±1 and analyzed at 0, 7, 14 and 21 days post-irradiation.

After electrophoresis performance, the accridine orange stain slides were seen under fluorescent microscope and the DNA comets were evaluated by photographic and image analysis.

Changes in microflora load of irradiated samples were also evaluated.

In all irradiated samples, the DNA fragments stretched or migrated out of the cells towards the anode of the agrose gel and appeared as a “comets” with tail.

Whereas, DNA comets of all non-irradiated samples were almost intact, round without tail or had very short tail.

Values of DNA % in tails and the tail length increased with increasing irradiation dose and storage times.

The DNA comet assay could successfully be used to detect radiation treatment of strawberry and deboned-chicken meat samples up to 7 and 21 days post-irradiation, respectively.

The absence of gram-negative bacteria and enterobacteriaceae group as well as the very low count of fungi (mostly yeasts) might be considered another evidence of radiation treatment of strawberries and fresh-deboned chicken.