Abstract:

Objective: To develop a determination method of o-tyrosine in g-ray irradiated protein-rich foods by highperformance 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 ofγ-ray.

Key words: o-tyrosine, γ-ray irradiated protein-rich food, HPLC, pre-column derivatization