Effects of cooking and storage on residues of cyadox in chicken muscle

The aim of this study was to investigate the depletion of residues of cyadox in chicken muscle over time. The heat stabilities of cyadox (CYX) and its two metabolites, 1,4-bisdesoxycyadox (BDCYX) and quinoxaline-2-carboxylic acid (QCA), in water, cooking oil, and as incurred residues in chicken muscle were investigated. CYX was shown to be unstable with a half-life of about 37.7 min in 100 °C water. In hot cooking oil at 180 °C, all three compounds were unstable. CYX decreased quickly and was not able to be detected after heating for 2 min. Diode-array analysis of CYX standard solution in cooking oil indicated that a portion of BDCYX was formed. The residues of CYX and BDCYX deteriorated rapidly in frozen storage, while that of QCA changed slowly. Muscles containing CYX residues were boiled, microwaved, or fried for the specified times. During boiling, CYX and BDCYX were reduced 94% and 81% in 10 min, respectively. During microwave cooking, CYX and BDCYX were reduced 54% and 47% in 2.5 min, respectively. During frying, CYX and BDCYX were reduced 86% and 76%, respectively. No significant reduction of QCA was found for the three cooking methods. The half-lives of CYX residues in cooked chicken muscles were estimated as follows: 2.22 min for CYX and 4.44 min for BDCYX by boiling; 6.66 min for CYX and 9.36 min for BDCYX by microwaving.