Researchers from the Università Cattolica, Piacenza campus, have detected the presence of two mycotoxins, ochratoxin and sterigmatocystin (produced by microscopic molds of the genus Penicillium and Aspergillus), in 48.6 percent and 94.4 percent, respectively, of packages of grated “grana” type cheeses purchased in supermarkets.
This is the finding of a study conducted by Professor Terenzio Bertuzzi and his collaborators from the Department of Animal, Food and Nutrition Sciences at the Catholic University, Piacenza campus, and published in the scientific journal Toxins. Funded by the Grana Padano and Parmigiano Reggiano consortia, the work highlights the presence, in small but significant amounts, of the two mycotoxins, ochratoxin and sterigmatocystin, the latter of which is considered emerging and for which the European Union has not yet established maximum limits to be observed.
In itself, the amounts of the two toxins traced in the 107 samples analyzed are not dangerous, the university informs in a note, but their consumption can add up to that found in other foods, such as cereals and derivatives, coffee, legumes, cocoa, nuts, wine, beer, cured meats, and raisins. Therefore, one must consider overall intake, the researchers emphasize. Overall, the risk to the consumer is really minimal; the legal limits set by the EU are precautionary limits, based on risk analysis, with the aim of minimizing the effects on our health.
Cheeses normally lend themselves to the growth of microscopic molds on their surface. During the long aging of hard cheeses (for grana, minimum 9 months), mold spores can settle on the surface of the cheeses, and under special environmental conditions in warehouses (humidity, temperature), some of these molds are able, as they grow, to produce toxic metabolites called mycotoxins (mykos = fungus).
Ochratoxin is among the best-known mycotoxins and is sought in cheeses; the presence of sterigmatocystin, on the other hand, is a novelty. The problem of these two mycotoxins concerns only grated cheeses (about a quarter – 25 percent – of all grana produced in Italy is processed and sold as grated), because in these packages the rind is also grated (for example, for grated grana the regulations allow a maximum use of 18 percent rind). Preventive practices exist and are followed; in aging warehouses belonging to the main protection consortia, the wheels undergo a cleaning process periodically. All cheeses, prior to marketing, are cleaned by washing with hot water or by dry abrasion and rind brushing treatments; with both, there is sanitization and a reduction in the levels of the two toxins in the grated product.
“The reduction in contamination would be greater by removing more rind, but this may not be necessary for many forms. This research showed how, thanks to careful and continuous cleaning and brushing, the products of the two protection consortia (Grana Padano and Parmigiano Reggiano) were safe for the consumer,” Bertuzzi concludes, “but it is important to be vigilant about the entire grated cheese sector.”