Correlation between multielement stable isotope ratio and geographical origin in Peretta cow milk cheese

This study was aimed at characterizing the isotopic composition and protecting “Peretta” cows’ milk cheese, a typical product of Sardinia, against other cheeses of the same appearance sold under the same name, but made of raw materials from Northern Europe. The study was concerned with three types of cheese: those produced in local dairies from milk from free-grazing or pasture-grazing cows in Sardinia (Local dairy-produced), cheeses made on an industrial scale from milk produced by intensive farming in Sardinia (Factory cheese) and cheeses made with raw materials imported from other countries (Imported product). To distinguish the Sardinian cheeses from the imported product the stable isotope ratios 13C/12C, 15N/14N, D/H and 34S/32S and 18O/16O were used. Determination of the isotopic data  13C, 15N, 2H and 34S was performed in the casein fraction, while 18O and 13C were determined in the glycerol fraction. Measurements were performed by Isotope Ratio Mass Spectrometry. A comparison between mean values of the isotope ratios by statistical analysis (ANOVA and Tukey’s test) showed that the greatest difference between the three types of cheese (local dairy-produced, factory product and imported product) was in the 13C/12C, 34S/32S and 18O/16O isotope ratios, while in the other parameters either no differences (15N) or minimal differences (2H) were found. Evaluation of the data by Multivariate Statistical Analysis (Principal Component Analysis and Hierarchical Cluster Analysis) revealed that the isotope characteristics of the factory products were similar to those of the cheeses produced from imported raw materials whereas a difference was found between the local dairy-produced cheeses and the products in the other two categories.