Effect of different Processing Methods on the reduction of Oxytetracycline residues in Tilapia (Oreochromis...

Oxytetracycline (OTC) is used as a therapeutic agent against bacterial pathogens in aquaculture, typically administered via medicated feed. Insufficient withdrawal time following drug treatment will result in antibiotic residue deposition in the tissues. Antibiotic residues are determined from freshly harvested fish tissues or processed fish samples for export purposes. But sufficient data is not available on the effect of different processing methods on the fate of antibiotic residues in fish tissues.

This study is aimed at understanding the effects of various processing/cooking methods on the retention of OTC residues in the edible fillets of OTC-fed tilapia.

Medicated feed was prepared by coating different doses of OTC into commercially available feed pellets and was administered to the fish in all the treatment groups for 10 days, and edible fillet samples were collected for various processing techniques, including boiling, microwave cooking, frying, and drying. The processed samples were analysed for OTC residues using Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS).

A Limits of detection (LOD) of 1.75 µg/kg and quantification (LOQ) of 5.82 µg/kg was achieved by the developed LC-MS/MS method for the quantification of OTC in fish samples. The results revealed a significant reduction of OTC in fish tissues following various processing methods. The maximum degradation was observed towards microwave processing and frying.

This study provides insights into the effectiveness of various cooking/processing methods for the efficient reduction of OTC residues in edible fish fillets.

The present study highlights the effects of different processing methods and demonstrates that even when some levels of drug residues are present in fish tissues, they can be effectively degraded using appropriate processing methods.