Cyclopropane fatty acids (CPFA), as lactobacillic acid and dihydrosterculic acid, are components of bacterial membranes and have been recently detected in milk and in dairy products from cows fed with maize silage. A specific quantitative gas chromatography–mass spectrometry (GC–MS) method for the detection of CPFA in cheeses has been developed. This method was applied to 304 samples of PDO cheeses of certified origin, including Parmigiano Reggiano (Italy), Grana Padano (Italy), Fontina (Italy), Comté (France), and Gruyère (Switzerland). Results showed that CPFA were absent in all of the cheeses whose Production Specification Rules expressly forbid the use of silages (Parmigiano Reggiano, Fontina, Comté, and Gruyère). CPFA were instead present in variable concentrations (300–830 mg/kg of fat) in all of the samples of Grana Padano cheese, where silage feeding is permitted. The method was applied to a mix of grated Parmigiano Reggiano and Grana Padano, showing that the method is able to detect the counterfeiting of Parmigiano Reggiano with other cheeses up to 10–20% Grana Padano content.
Read the full abstract: http://pubs.acs.org/doi/abs/10.1021/acs.jafc.6b00913?journalCode=jafcau
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