Aflatoxin M₁ occurrence in fluid milk commercialized in Monterrey, Mexico

The occurrence of aflatoxin M₁ (AFM₁) in milk samples commercialized in the Metropolitan area of Monterrey (Mexico) was evaluated by employing the competitive enzyme linked immunosorbent assay (ELISA) technique. For this, 84-fluid milk samples, with diverse origin (80% national production, 20% imported milk) and heat treatments (26% pasteurized and 74% Ultra High Temperature (UHT)-treated) were collected in different sales points. In all the evaluated samples, the AFM₁ was detected, with values oscillating from 0.1 to 1.27 μg/L. According to the Food and Drug Administration (FDA) and Mexican standards, concerning a maximum limit of 0.5 μg/L, 39% of the analyzed samples were out of the standard limit, with different results depending on the milk origin (46% and 18% for national and imported milks, respectively) and heat treatment applied (45% and 23% for UHT and pasteurized samples, respectively). Based on these results, it is necessary a higher effort to control AFM₁ levels in milk consumed in Mexico. Practical applications: The practical application of this document is to serve as a first approach to know the presence of aflatoxins in milk in northern Mexico, both in domestic and imported products, and under different heat treatments applied and from this, take different measures by authorities and producers with a view to reducing their presence in milk and other dairy products.