Comparison of Yogurt Test with Commercial Kit for Detection of Antibiotic Residues in Raw and Pasteurized Milk

BACKGROUND: Antibiotics are widely used for the treatment of livestock. Their inappropriate usage leads to various disorders in humans as a result of consuming animal products. Milk is among the foods that are significantly affected by consuming antibiotics. OBJECTIVES: The objective of this study was to compare Yoghurt Culture Test (YCT), Four- Plate Test (FPT), and the Copan test for detecting antibiotic residues in raw and pasteurized milk produced in Chaharmahal and Bakhtiari province, Iran. METHODS: A total of 146 raw milk samples and 54 pasteurized milk samples were selected randomly from dairy farms and dairy products suppliers. The presence of antibiotics was evaluated by YCT, FPT, and Copan test. In addition, the sensi-tivity of the three tests for tetracycline and penicillin, as the two common antibiotics in the treatment of animals, was compared. RESULTS: Our findings showed that 8.9% of raw milk and 11% of pasteurized milk samples contained antibiotics. However, the levels of antibiotic residues were higher in 2% of the positive samples than maximum residue levels (MRL). Moreover, significant differences were observed between FPT, YCT, and the Copan test (P 0.05). On the other hand, the positive results of YCT and Copan tests were not significantly different (P 0.05). CONCLUSIONS: The results of this study showed that a low percentage of milk samples contained antibiotic residues higher than the permissible limit. Furthermore, YCT could be used as an inexpensive, easy, and sensitive method for identifying the residues of penicillin and tetracycline in milk.