The frequency of aflatoxin M1 detected by ELISA and high performance liquid chromatography in raw and pasteurized milk in the northern province of Kerman

The aflatoxin M1 (AFM1) is present in the milk of livestock fed on contaminated feed. This study was conducted based on the fact that milk is one of the main sources of aflatoxin contamination in human. In order to record the frequency of AFM1, a total of 207 milk samples including 153 raw milk samples from 12 different regions of Kerman province and 54 pasteurized milk samples produced in 10 dairy factories of Kerman province were checked by Elisa. Results showed that the concentration of AFM1 in 41.2% of raw and 35.2% of the pasteurized samples was above the maximum acceptable level (100 ng/L) approved by National Institute of Standard, Iran. The amount of AFM1 in pasteurized milk was significantly lower than that in the raw milk. In order to confirm the results of ELISA, 24 samples of raw milk and 2 samples of pasteurized milk were also evaluated by HPLC, from which, four positive and five negative samples were finally confirmed. Although there was no significant correlation between the number of positive and negative samples in both methods, the concentration of AFM1 was significantly correlated. The sensitivity and the specificity of the ELISA test was respectively 100% and 25%. Since the concentration of aflatoxin was higher than the accepted level, a proper strategy of feeding management of the dairy farms in the province are suggested. In spite of the fact that ELISA is a suitable method for screening of AFM1, using a method with higher specificity is also recommended.