Application of multielement stable isotope ratio analysis to the characterization of French, Italian, and Spanish cheeses

The stable isotope ratios (delta(13)C, delta(15)N, and delta(34)S of casein and delta(13)C and delta(18)O of glycerol) measured by IRMS of French, Italian, and Spanish cheeses are presented and discussed. Variability factors such as animal-feeding regimen, geographical origin, and climatic and seasonal conditions were studied to check the possibilities of cheese characterization offered by each isotopic parameter. delta(13)C values of both casein and glycerol appeared to be strongly correlated to the amount of maize in the animal diet. delta(15)N and delta(34)S of casein proved to be mostly influenced by the geoclimatic conditions of the area (aridity, closeness to the sea, altitude). delta(18)O of glycerol was more dependent on the geographical origin of the cheeses and on climatic/seasonal parameters. By applying a multivariate stepwise canonical discriminant analysis, good discrimination possibilities for the different European cheeses were obtained, confirmed by the classification analysis, when >90% of the samples were correctly reclassified.