Sources of variability of H, C, O, N and S stable isotope ratio in dry-cured ham

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 the stable isotope ratios of the most important bioelements (2H/1H, 13C/12C, 15N/14N, 18O/16O, 34S/32S). Overall, 11 isotope ratios were examined in three ham fractions: defatted dry matter of biceps femoris muscle and fat of biceps femoris muscle and subcutaneous adipose tissue. The experimental hams were made out of pigs reared in three geographical areas (two in Italy – Friuli and Emilia – and one in Spain). In every location different productive factors were assessed as a potential source of isotope ratio variability, following suitable experimental designs. In particular, the effect of pig genetic type and rearing system was examined on 36 hams from heavy pigs belonging to three genotypes (Cinta Senese, Mora Romagnola and a commercial hybrid) kept on the same diet in Friuli both in stable or outdoor, in a fenced woody area. The influence of pig feeding regime was analysed by comparing the isotope ratios of 26 Dehesa de Extremadura PDO hams, obtained from heavy pigs fattened outdoor on grazed feedstuffs without (“Bellota” Iberian hams) or with concentrate supplement (“Campo” Iberian hams). The processing influence was examined on 36 hams from pigs reared on the same farm and diet in Emilia and seasoned for three different periods following the procedures of the three main Italian PDO hams (Parma, San Daniele and Toscano). The subcutaneous fat of these hams was sampled at both the outer (as usual) and inner layer. The first results indicate that the processing procedure factors and pig genotype do not have effect on the stable isotope ratios, whereas the geographical origin and the pig feeding regime have a significant effect.