To explain the formation of protein nitration marker, 3 nitrotyrosine (3NT), in food products was the basis for the present study. For the accurate detection as protein nitration marker of 3NT in food products, i) a new method was improved, which is optimized parameters affected the formation of 3NT, ii) HPLC-DAD was applied as a straightforward and rapid methodology and iii) finally the suspensions representing meat and dairy products were prepared and this method was used to these suspensions to evaluate the convenience of it. For comparative purposes, the spectrophotometric method of the determination of 3NT level was also employed to assess the 3NT level. The results showed that optimized method enabled detection of 3NT level in food systems and 3NT could act as a protein nitration biomarker in food. This study will shed light on the understanding of precise mechanisms about protein nitration and contribute to the change of amino acids during processing and storage.