2000 Volume 46 Issue 4 Pages 304-309
An o-Tyrosine method for detection of irradiation of foods was studied by HPLC using a novel light amplification by stimulated emission of radiation (LASER) fluorometric detection system with pre-column reaction. Sample was prepared and purified by eliminating fat and sugars using a mixture of acetone and chloroform, and then the purified protein was hydrolyzed using hydrochloric acid at 110°C for 24h in a vacuum. The sample was reacted with 4-fluoro-7-nitrobenzofurazan (NBD-F) reagent by an automatic pipetting system and was introduced into the HPLC system. Irradiated chicken, pork, beef, and tuna were examined by irradiating at 0, 1, 5, 10 kGy. Irradiation of chicken and pork irradiated at or over 10 kGy was successfully detected, but that of beef and tuna were more difficult to detect. After 3 months storage at-20°C, the irradiation was still detectable in chicken irradiated at 10 kGy. Thus this detection procedure can be used to detect irradiation in some chilled meats irradiated at 10 kGy. Non-irradiated o-tyrosine formation and reduction of o-tyrosine by hydroxylation are also discussed.
