Evaluation of Aflatoxin M1 Enrichment Factor in Semihard Cow's Milk Cheese and Correlation with Cheese Yield

The fate of aflatoxin M1 (AFM1) in cow's milk cheese produced from naturally contaminated raw milk was evaluated. Cow's milk, naturally contaminated by AFM1 at levels ranging from 0.020 to 0.148 µg/kg, was used to manufacture a semihard, ripened Caciotta cheese. The cheeses, produced in eight cheesemaking trials, were ripened for 45 days. The enrichment factor (EF) of cheese did not change during maturation from day 7 to day 45 of ripening. The EF of the aflatoxin was established to evaluate the maximum level of contaminants in cheese, according to Commission Regulation (EC) No. 1881/2006. The EF factor in cheese at 45 days of ripening was between 4.68 and 5.78, with a mean value of 5.16. Moreover, this factor was not affected by the AFM1 level in milk. Pearson's correlation analysis showed a significant negative correlation between EF and cheese yield (r = -0.811). The regression analysis confirmed that the cheese yield and, subsequently, the milk composition, had a marked impact on EF (P < 0.0003). Cheese yield was identified as potentially influencing the presence and concentration of the toxin in cheese, demonstrating that this aspect, along with the cheese hardness category, contributes significantly to an exact definition of the EF.