Effects of Different Processing Methods on the Antibiotic Enrofloxacin Residues Occurrence in Middle Eastern Dairy Products

Abstract

Antibiotics are used to treat or prevent certain diseases caused by infectious agents. Over the past years, Lebanon has witnessed an increasing consumption of antibiotics through medications and food supply. There is a well-reported link between using antibiotics in farming and developing antibiotic resistance, which leads to subsequent human antibiotic treatment failure. Our first-of-its-kind study in the region aims to determine the effects of different dairy processing unit operations (pasteurization, skimming, curding, pressing, boiling/acidifying, and salting) on Enrofloxacin (ENF), a widely used antibiotic in Lebanon. For this, full fat and skimmed milk were inoculated with ENF, and processed into pasteurized milk along with commonly consumed Middle Eastern products (Baladi, Double Crème, Halloum and Akkawi) in a major dairy industry. Liquid Chromatography Mass Spectrometry (LCMS), the gold standard method, was used to quantify ENF residues. Results showed that pasteurization (Holder and High Temperature Short Time) significantly decreased ENF concentration. A significant increase in ENF by 3.5 folds was reported upon curding milk into Baladi, and by 1.9 folds upon acidifying/boiling the whey into Double Crème. Pressing Baladi to produce Akkawi did not have any significant effect on ENF concentration, while boiling Akkawi to produce Halloum decreased it significantly. Salting Halloum in brine (12%) did not have any significant effect. Our results will help the local authorities to set MRLs of ENF in dairy products. They will also guide the dairy industries to decide on which product to process the raw milk to whenever they receive milk contaminated with ENF to ensure the safety of their products.