Tracking of enrofloxacin antibiotic in the making of common middle eastern cheeses

Our study aims to determine the effects of different processes (skimming, pasteurizing, curding, pressing, boiling and salting) on enrofloxacin during the making of commonly consumed Middle Eastern products (Baladi, Akkawi, Halloum, Double Cream), which have flow diagrams of production that are particular to them. This was done by spiking milk with the antibiotic, skimming, and then processing it to cheeses. Liquid chromatography-mass spectrometry was used to measure enrofloxacin. Pasteurization (both holder and high temperature short time) significantly (p < 0.05) decreased the concentration. A significant (p < 0.05) increase by 3.5 folds was reported upon curding milk into Baladi, and by 1.9 folds upon acidifying/boiling the whey into Double Cream. Pressing Baladi to produce Akkawi did not have any significant effect, while boiling Akkawi to produce Halloum decreased enrofloxacin significantly by 5 folds. Salting Halloum did not have any significant effect. Our results will help the local authorities to set maximum residue levels of enrofloxacin in dairy products. They will also assist the dairy industries to decide on which product to process the raw milk to whenever they receive milk contaminated with enrofloxacin to ensure the safety of their products.