Analysis of Veterinary Drug Residues in Pasteurized Milk Samples in Chinese Milk Bars

The milk bar is an emerging style of retail business that mainly produces pasteurized milk (PM) and other dairy products on-site in many large cities of the People's Republic of China. To date, no data about veterinary drug residues in PM samples produced from milk bars have been reported. The objective of this study was to investigate the safety of PM from a total of 182 PM samples collected from milk bars from 10 provincial capital cities and to analyze the residues of seven classes of 61 veterinary drugs. First, the chemical components were screened with test kits, and then the positive samples were further confirmed by ultraperformance liquid chromatography-tandem mass spectrometry. The results showed that 15 (8.24%) samples were screened positive for veterinary drugs, and six drugs in 11 (6.04%) samples were confirmed. The veterinary drugs detected were penicillin G (2.20%), tetracycline (1.10%), tylosin (1.10%), amoxicillin (0.55%), oxytetracycline (0.55%), and gentamicin (0.55%), with maximum residue levels of 3.4, 11.9, 28.2, 3.0, 26.9, and 63.5 μg kg-1, respectively. Veterinary drug residues were detected as positive in 7 of 10 cities, with the highest detection rate as 14.29% in Urumqi. No positive samples were found in the cities of Nanjing, Tianjin, and Nanning. All detected drug levels were far below the maximum residue levels regulated by China, the European Union, and the Codex Alimentarius Commission. This suggests that the overall veterinary drug residues in PM in milk bars reached the safety code of the country. However, potential risks still exist, and continuous attention should be paid to guarantee the safety of this milk product in the future.