The Effects of Roasting and Microwave Processes at Different pH Values on Enrofloxacin, Oxytetracycline, and Sulfadiazine Residues in Chicken Meat

The present research aimed to evaluate the effects of roasting and microwave thermal processes along with pH change on the amount of residues of three commonly used antibiotics, enrofloxacin, oxytetracycline and sulfadiazine in chicken meat. For this purpose, first the three antibiotics were added to the chicken meat samples in amounts 4 times the remaining limit. Meat samples containing residues of each antibiotic were subjected to roasting (at 200 °C for 30 minutes) and microwave (at 100 °C for 3 minutes) treatments at pH 5.8 and 4.8. Then, the residual amount of each of the antibiotics was investigated by high-performance liquid chromatography (HPLC) along with colorimetry and evaluation of cooking loss. The results showed that both treatments were able to significantly reduce the amount of antibiotic residues, but both processes were more effective at pH 4.8 than 5.8 (P<0.05). The highest amount of reduction of antibiotic residue at pH 4.8 in both microwave and roasting treatments was observed in oxytetracycline residue with 76.2 and 72.4% respectively. Roasting and microwave treatments decreased L* index, but a* index decreased in roasting and increased in microwave, and b* index increased in microwave, but there was no significant change in roasting. Also, the amount of cooking loss in roasting in the range of 58 to 71% was more than that of microwave in the range of 48 to 62% (P<0.05). Finally, microwave treatment can be introduced along with reducing the pH of chicken meat to 4.8 as the best treatment to reduce antibiotic residues.