Comparison Between the Amount of Penicillin G Residue in Raw and Pasteurized Milk in Iran

Background: There is a worldwide concern about the life quality, in this way, one of the most important requirements is safe and nutritious foodconsumption. The administration of antibiotics to cattle in order to treat several infectious diseases has contributed to the contamination of industrialized dairy farms. Objectives: Milk antibiotic contamination is an important problem worldwide, and the quality control of milk samples is essential. Therefore, the aim of this study was to monitor antibiotic contamination in milk samples. Materials and Methods: Samples were collected from six different farms and milk factories in Iran, and were tested by beta-star and cylinder-plate methods. Results: Among 992 raw milk samples, 236 positive samples, 9 suspected and 747 negative samples in respond to beta-star test and among 236 samples, which had positive responses to beta-star test, 28 positive, 0 suspected and 208 negative results of cylinder-plate test were gained. Among 652 pasteurized milk samples, 67 positive, 9 suspected and 576 negative beta-star test results and among 67 samples which had positive responses to beta-star test, 1 positive, 0 suspected and 66 negative results to cylinder-plate test were achieved. Conclusions: The results revealed that cylinder-plate method accompanied with beta-star test can be considered as an appropriate sensitive and selective method for the milk and dairy products quality control. According to the results, it look as if the process of pasteurization reduces the amount of penicillin G in milk samples considerably.