H, C, N and O stable isotope characteristics of alpine forage, milk and cheese

H, C, N, O stable isotope ratios of forage, milk and the corresponding cheese were analysed to define the isotopic characteristics of two typical mountain cheeses produced in two different terroirs with different types of vegetation. d13 C was shown to be mainly influenced by the presence of C4 plants in animal diet and, in the case of C3 plant-based forage it was below23&varying according to the site and herbage type. d15 N is more related to vegetation type and confirmed to be lower thanþ4&for alpine products. The altitude of the origin area influenced 18 O and d2 H. The isotopic values of milk and cheese casein were not significantly different, except d18 O, while they were both significantly different from the values of forage, except d2 H. Using the combined stable isotope ratios a good discrimination level between the products from two different types of pasture at two mountain sites was achieved.