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Rationale: No study has investigated the variations in stable isotope ratios (SIRs) of bioelements within a Protected Designations of Origin (PDO) cheese and few studies have focused on the dietary background of animals. For traceability purposes, it is important to know how and whether these issues affect SIRs in a PDO cheese., Methods: Thirty-six Pecorino Siciliano cheese samples were collected in three east-Sicilian areas in seasons in which green herbage was present or absent in the diet of the animals. The determination of C, N and S SIRs was performed using an isotope ratio mass spectrometer coupled with an elemental analyser. The H and O SIRs were measured using an isotope ratio mass spectrometer equipped with a thermal conversion elemental analyser pyrolysis unit., Results: The C, N, H, O and S SIRs measured in defatted cheeses were subjected to a multivariate stepwise discriminant analysis to verify if cheeses could be distinguished based on their geographical origin and on the animals' feeding regimen. Sulfur and nitrogen SIRs allowed the best discrimination among the three areas (97.2% correct classification of the cheeses). The discrimination of the feeding system, to check the presence or not of fresh forage in the diet of the animals, correctly classified 86.1% of the cheeses. The C and O SIRs were the most effective parameters., Conclusions: This study demonstrates that the variability in C, H, O, N and S SIRs can allow discrimination between cheeses produced in a narrow geographical region within a PDO area. This may lead to the search for new tools in authentication studies such as the creation of specific isoscapes. Moreover, this study confirms that SIR determination can also discriminate cheeses obtained from animals fed in stalls from those produced when animals have access to green forage, with benefit in terms of environmental impact, animal welfare and product quality. Copyright © 2017 John Wiley & Sons, Ltd., (Copyright © 2017 John Wiley & Sons, Ltd.)

This study was aimed at determining whether isotopic ratio mass spectrometry (IRMS) enables us to discriminate between lambs fed herbage or concentrate, both obtained from C(3) plants, and those fed a concentrate obtained from C(4) plants. Thirty-four Comisana male lambs (age 45 days) were assigned to three feeding treatments. Fourteen lambs were fed vetch (Vicia sativa) ad libitum. Another fourteen lambs received a barley-based concentrate. The remaining six lambs were fed a maize-based concentrate. After 60 days of experimental treatment the animals were slaughtered and the wool, perirenal fat and muscle longissimus dorsi were sampled. The delta(13)C and delta(15)N values of the muscle, wool and feed were measured by continuous flow elemental analysis (CF-EA)-IRMS. The delta(13)C of the fat was determined likewise. The isotopic composition of the tissues reflected that of the three diets. For the lambs which were fed herbage the muscle delta(13)C values were higher (P < 0.0005) and delta(15)N values were lower (P < 0.0005) than those of the lambs receiving concentrates. The delta(15)N and delta(13)C values in the muscle and delta(13)C values in the adipose tissue allowed perfect discrimination between the lambs fed the three different diets. The regression between the delta(13)C values measured in muscle and in wool of lambs was linear (R(2) = 0.99; P < 0.0005). This result shows that delta(13)C measured in the wool can predict muscle delta(13)C distribution, suggesting that wool is a valuable matrix for meat authentication.