H, C, N and S stable isotopes and mineral profiles to objectively guarantee the authenticity of grated hard cheeses

In compliance with the European law (EC No. 510/2006), geographical indications and designations of origin for agricultural products and foodstuffs must be protected against mislabelling. This is particularly important for PDO hard cheeses, as Parmigiano Reggiano, that can cost up to the double of the no-PDO competitors.This paper presents two statistical models, based on isotopic and elemental composition, able to trace the origin of cheese also in grated and shredded forms, for which it is not possible to check the logo fire-marked on the rind. One model is able to predict the origin of seven types of European hard cheeses (in a validation step, 236 samples out of 240 are correctly recognised) and the other specifically to discriminate the PDO Parmigiano Reggiano cheese from 9 European and 2 extra-European imitators (260 out of 264 correct classifications). Both models are based on Random Forests. The most significant variables for cheese traceability common in both models are δ13C, δ2H, δ15N, δ34S and Sr, Cu, Mo, Re, Na, U, Bi, Ni, Fe, Mn, Ga, Se, and Li. These variables are linked not only to geography, but also to cow diet and cheese making processes.

Graphical abstract. Random Forest model based on δ13C, δ2H, δ15N, δ34S and the content of Sr, Cu, Mo, Re, Na, U, Bi, Ni, Fe, Mn, Ga, Se, Er, Dy, Pb, Li, usable for the protection of PDO Parmigiano Reggiano cheese from mislabelling. The correct classification rate in cross-validation is 98.6%.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The isotopic and elemental profile of over 260 hard cheese samples are discussed. ► Two validated and immediately applicable statistical models are presented. ► One model is able to predict the origin of seven types of European hard cheeses. ► The other one allows to discriminate the PDO Parmigiano Reggiano cheese from imitators. ► The most significant variables are δ13C, δ2H, δ15N, δ34S and the content of 16 elements.