Transfer of antibiotics from goat's milk to rennet curd and whey fractions during cheese-making

The transfer of 35 antibiotics from milk to curd and whey was evaluated. Cheeses were produced at laboratory scale, from antibiotic-free goat's milk spiked with different antibiotic concentrations between 0.25 and 4 times the Maximum Residue Limits established in milk. Drug concentrations in milk, curd and whey were analysed by UHPLC-HRMS. Results indicated that most antibiotics were mainly transferred from milk to whey (up to 85.9%), with retention percentages in the curd lower than 50%, except for ceftiofur (59.7%) and dicloxacillin (52.8%). In most cases, drug distribution was unaffected by the antibiotic concentration in milk and correlated significantly to the drug lipophilicity (Log P) for beta-lactams (R-2 = 0.54) and sulfonamides (R-2 = 0.62). When drug ionization was considered (Log D), improved correlation coefficients were obtained for macrolides (R-2 = 0.98). However, other factors besides the drug solubility should be considered to explain and predict the partitioning of antibiotics during cheese-making.

Automated summary

The transfer of 35 antibiotics from milk to curd and whey was evaluated. Most antibiotics were transferred from milk to whey, with lower retention percentages in the curd. The drug distribution correlated with drug lipophilicity and ionization.