Detection of Irradiated Frozen Deboned Seafood with the Level of Radiolytic H2 and CO Gases as a Probe

A method to detect irradiated frozen shrimp without cuticle, cod slices, and deshelled oyster has been developed based on the fact that radiolytic H2 and CO gases are retained in the irradiated samples for a certain period during the storage. These gases could be recovered from irradiated frozen samples in the headspace of a gastight glass screw vial by microwave heating. Gas chromatographic analysis of the headspace gas revealed that significant amounts of H2 and/or CO gases were retained in the irradiated samples. Using those gases as a probe, irradiated frozen shrimp could be distinguished from non-irradiated shrimp for 3 months after 1.1−8.8 kGy irradiation, and irradiated frozen cod slices and oyster could be distinguished for at least 2 months at the dose ranges of 1.4−5.5 and 1.2−6.0 kGy, respectively. Keywords: Radiolytic H2 gas; radiolytic CO gas; irradiation; detection; deboned seafood; food irradiation