Study on detection method of irradiated frozen foods and others

As detection method of the irradiated foods has history of 20 years, it is said that it has no finished chemical method, which is longed to construct as soon as possible. Up-to-date, many kinds of chemical detection methods have been proposed, the o-tyrosine method thought to be hopeful for the irradiated frozen foods among them was selected to investigate. In this method, phenyl alanine is oxidized with a radical formed on irradiation to tyrosine. The o-tyrosine out of the formed isomers is analyzed quantitatively. When irradiation γ-ray to foods, it was found that amounts of o-tyrosine increased to reach about 2 or 3 times of original amounts. This result was also found to agree with the result reported at the ADMIT conference. Furthermore, possibility of judgement using this method was also shown because of difference on 2 or 3 times of o-tyrosine amounts between unirradiated and over 5 kGy irradiated foods. (G.K.)