Transfer of aflatoxin M1 from milk to ripened cheese in three Italian traditional production methods.

Robiola and Primosale, two fresh cheeses, and Maccagno, an hard-type cheese, were produced using milk that was naturally and artificially contaminated with aflatoxin M1 (AFM1) at the levels of 10, 50 and 200 ng/l. Concentrations of AFM1in milk and cheeses were determined by liquid chromatography and fluorimetric detection, coupled with immunoaffinity column extraction. In the Robiola production method, AFM1 levels in whey ranged between 30% and 65% of the total amount of the toxin present in the milk, while Primosale and Maccagno, that share the same rennet based cheesemaking procedure, showed an higher percentage of AFM1 partitioning to whey. For each cheese-making method, the concentration of AFM1 on fresh matter was higher in the cheese compared to the original milk. The fresh cheeses showed a concentration factors of 1.43 and 2.20 for Primosale and Robiola, respectively, whereas the Maccagno cheese showed a value of 6.71. For all the production methods considered, when using milk not exceeding the maximum acceptable level of 0.05 mg AFM1/kg set by EU, the resulting cheese also complied with current Italian recommendations for AFM1 contamination (450 ng AFM1/kg).