Occurrence of aflatoxin M1 in Italian cheese: Results of a survey conducted in 2010 and correlation with manufacturing, production season, milking animals, and maturation of cheese

Aflatoxin M1 (AFM1), a carcinogenic metabolite secreted into milk by animals fed with crops contaminated by aflatoxin B1, can be found in dairy products because of its relative stability to treatments used to produce foodstuffs, and also to long-term storage. Maximum admissible limits of AFM1 in milk have been set up worldwides; specific regulations regarding dairy products have also been established in some countries. Nevertheless, little and rather discordant data on the occurrence of such a contaminant in cheese and other dairy products is available, and mainly in those countries which are important producers and consumers of cheese, such as, for example, Italy. Therefore, a one-year survey was conducted by measuring AFM1 contamination in cheese purchased on the Italian market. More than a hundred samples representing the highest variability in terms of type of cheese, origin, cheese-making process, and maturation were collected and analysed through a previously described ELISA method coupled to a very rapid, simple and solvent-free extraction. More than 83% of samples showed detectable levels of AFM1 (>25 ng kg−1); most of them were found to be contaminated at a level between 50 and 150 ng kg−1. The measured AFM1 concentration was correlated to four factors which were presumed to influence the contamination level: manufacturing, production season, milking animal, and maturation. Statistical analyses demonstrated that milking animals and manufacturing affect AFM1 concentrations, as cheeses obtained from cows' milk and from artisanal production are more contaminated than cheeses produced with milk belonging to other animals and in industrial contexts. The others two factors showed statistically non-significant differences between groups.

► The occurrence of aflatoxin M1 in Italian cheese was studied. ► A simple aqueous extraction was used to enlarge the number of processed samples. ► The highest levels of contamination were evidenced in cheese made with cows' milk. ► Small-scale produced cheeses were more contaminated than those from big brands. ► Production season and maturation did not affect AFM1 contamination.