Isotopic methods for dry-cured ham traceability. The stable isotopes ratios (IR) of bio-elements, which depend on botanical, geographical, agronomic and climatic factors that are transmitted from water and vegetables to animal products, are potential indicators of meat production and processing systems. The aim of the study was to ascertain the effect of the geographical origin and the production process of dry-cured ham on the variability of D/H, 13C/12C, 15N/14N, 18O/16O, 34S/32S ratios, measured by IR Mass Spectrometry after total combustion or pyrolysis. Overall, 11 IR were examined in three ham fractions: defatted dry matter (DFDM) and fat of biceps femoris and subcutaneous adipose tissue. The hams were made out of pigs reared in three geographical areas, where different productive factors were studied. The effect of pig genetic type and rearing system was examined on 36 hams from heavy pigs of two genotypes (local breed and commercial hybrid) kept on the same diet and conditions in Friuli. The influence of feeding regime was analysed by comparing the isotope ratios of 26 Dehesa de Extremadura PDO hams, from heavy pigs fattened outdoor on grazed feedstuffs without (“Bellota” ham) or with (“Campo” ham) concentrate supplement. The processing influence was examined on hams from pigs reared on the same farm and diet in Emilia and seasoned for different periods following in the same ham plants. By applying the stepwise linear discriminant analysis, 98.8% of hams were correctly assigned and 97.7% correctly cross-validated into six different types, by a model including the five IR of DFDM, together with 18O/16O of marbling fat and 13C/12C of subcutaneous fat. A full discrimination of origin was obtained while, within location, autochthonous breed, feeding regime and stage of seasoning had a significant effect on IR variability.
