Determination of o-Tyrosine in γ-Ray Irradiated Food by HPLC

WANG Dong-hui1,WANG Min2,HAN Li2,DENG Xiao-jun2,SHENG Yong-gang2 (1. Shanghai Institute of Measurement and Testing Technology,Shanghai 200135,China;2. Shanghai Entry-Exit Inspection and Quarantine Bureau,Shanghai 200135,China)

o-tyrosine;γ-ray irradiated protein-rich food;HPLC;pre-column derivatization

Objective;To develop a determination method of o-tyrosine in g-ray irradiated protein-rich foods by high- performance liquid chromatography coupled with pre-column derivatization. Methods;Sample was homogenized and purified by eliminating fat and sugars with the mixture of acetone and chloroform (3:1, V/V), and then deproteinated by means of hydrolysis with hydrochloric acid at 110 ℃ for 24 h. After reacting with derivative reagent, the sample digestion solution was subjected to HPLC analysis by external reference method. Results;The detection limit of o-tyrosine by this method was 5 mg/kg. The recoveries of o-tyrosine at the spiked amounts of 5, 10, and 50 mg/kg were 62.1% to 88.3%, and the coefficients of variation were 3.91% to 9.38% (n = 6). Conclusion;The o-tyrosine content in chicken and pork irradiated with 5 kGy and above ofγ-ray can be successfully detected, which is obviously higher than that in unirradiated meat samples and presents linear relationship with irradiation dose. After 3-month storage at -20 ℃, the o-tyrosine is still detectable in chicken and pork irradiated with 5 kGy and above of γ-ray.