Effectiveness of Cooking Procedures in Reducing Antibiotic Residues in Bivalves.

Abstract

Background/Objectives: The widespread use of antibiotics, which wastewater treatment plants (WWTPs) cannot fully remove, in human and veterinary medicine leads to their release into wastewater, resulting in the contamination of aquatic environments. Bivalves can accumulate these antibiotics, posing a risk to shellfish consumers, including potential antimicrobial resistance. This study aimed to assess how three cooking methods-marinating, steaming, and grilling-affect the concentration of 33 different antibiotics in bivalves fortified at the level of maximum residue limit (MRL) and twice the MRL (2MRL). Results: The data show the percentage of antibiotic remaining after cooking: 100% indicates stability or no reduction; values above 100% show an increase in concentration, and values below 100% reflect a decrease in antibiotic concentration. In general, all culinary procedures removed part of the added antibiotics. However, the most effective method was marinating (47%), followed by steaming (60%) and finally grilling (92%). It was also found that, overall, the fortification level, MRL or 2MRL, did not impact antibiotic removal in each cooking method. Moreover, different antibiotics' classes presented diverse removals when cooked, ranging between 0% for penicillins and 73% for sulphonamides. Furthermore, the results showed a great diversity of responses to cooking within some antibiotic classes. Methods: After cooking, the analysis was based on solid-liquid extraction followed by liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-ToF-MS). Conclusions: The ongoing monitoring of antibiotic levels is essential, and further research is needed to understand how cooking affects these substances and their metabolites. This will help assess the real risk to consumers and guide risk-mitigation measures.