A parmesan cheese scandal earlier this year highlighted how easy it is to alter the cheese when it's grated. For producers and consumers of some of the most expensive kinds, this is a big problem. Generic versions abound, but the traditional variety comes from only a handful of provinces in Italy and commands twice the price.
Now, scientists reported in the Journal of Agricultural & Food Chemistry a way to catch adulteration of the regional products.
In February, news stories emerged about grated Parmigiano Reggiano, or parmesan, cheese that used cellulose as a filler and contained different, less-expensive cheeses. One product labeled 100% parmesan reportedly contained no actual parmesan. For consumers interested in artisanal products, there was no way to truly know what they were getting at the store.
To address this issue, the European Union established a system to grant a "protected denomination of origin" (PDO) designation to certain products. In the case of Parmigiano Reggiano, cheeses with the PDO label must meet certain requirements. For example, they must be made out of milk from cows that are not fed silage, a fermented cereal product often used in animal feed.
Augusta Caligiani and colleagues at the Università degli Studi di Parma in Italy wanted to see if detecting compounds associated with these diets would be an effective way to determine the authenticity of PDO-labeled parmesan.
The researchers analyzed more than 300 samples of cheeses using a gas chromatography-mass spectrometry method to see if it could help differentiate cheeses from cows fed silage versus those that were not. The team found that samples of Grana Padano, a cheese similar to parmesan but made with milk from cows that are allowed to eat silage, contained cyclopropane fatty acids. However, these fatty acids were not in PDO parmesan samples.
The researchers also could tell if a blend of the two cheeses contained 10% or more of Grana Padano. Because the method is simple and fast, the researchers said it could be used in the industry to screen large numbers of samples for potential adulteration.