Beta-Lactam Antibiotic Stability in Chicken Meat.

Background/

Objectives

Residues of β-lactam antibiotics in foods of animal origin are important for official residue control and public-health risk assessment. Sample storage conditions may affect the measured concentrations of these analytes, whereas cooking may influence consumer exposure. This study evaluated the stability of six β-lactam antibiotics-amoxicillin, ampicillin, phenoxymethylpenicillin, benzylpenicillin, cefazolin, and cefotaxime-and clavulanic acid, a β-lactamase inhibitor, in chicken meat during storage and thermal processing.

Methods

Incurred chicken meat samples were obtained after in vivo administration of the studied compounds. Stability was assessed during storage at +4 °C, -20 °C, and -86 °C for up to 165 days, during repeated freeze-thaw handling, and during heating at 100 °C for up to 30 min. The target compounds were quantified by HPLC-MS/MS after acetonitrile extraction and hexane clean-up.

Results

The studied compounds were unstable at +4 °C, with concentrations decreasing below the detection limit within 3-27 days depending on the compound. Storage at -20 °C was insufficient for long-term preservation of most penicillins, whereas -86 °C improved stability. Cefazolin was the most stable compound under the tested storage conditions, while cefotaxime was the least stable. Heating at 100 °C for 30 min caused substantial reduction in parent-compound concentrations, ranging from 63.8 ± 4.0% for cefazolin to complete disappearance below the detection limit for cefotaxime.

Conclusions

For reliable official residue analysis, chicken meat samples intended for β-lactam testing should be stored at -86 °C whenever long-term storage is required. Repeated thawing should be avoided. Cooking substantially reduces the concentrations of the parent compounds but cannot be considered a reliable safety measure, because degradation may be incomplete and degradation products were not assessed in this study.