Discrimination of beef production system and regional geography by multivariate analysis of stable isotope ratios (C, N, S, O, H)

The validity of discriminating Irish beef according to its dietary background using stable isotope ratio analysis (SIRA) was investigated. The influence of the cattle production system typified by diet on the isotopic profile of beef muscles was examined. Both dietary category and geographical origin affected the isotopic composition (δ 13 C, δ 15 N, δ 34 S, δ 18 O and δ 2 H) of beef. A canonical discriminant analysis (CDA) model was developed and validated using the stable isotope ratios in M. longus colli muscle from cattle reared on either high grass, partially grass or high cereal concentrate diets in a controlled environment. The results demonstrated that the model could successfully classify these control samples (accuracy = 100%). For commercial beef (also M. longus colli ), CDA also discriminated samples according to two distinct grass- and concentrate-fed production systems (accuracy = 68.3 - 81.1%). The discriminant analysis approach demonstrated the potential of stable isotope ratios for authenticating grass-based beef. • Diet and geography affected the isotopic composition of commercial beef • All isotopes (δ 13 C, δ 15 N, δ 34 S, δ 18 O, δ 2 H) implicated. • Canonical discriminant analysis discriminated beef from the most divergent diets • Discrimination of commercial beef from intermediate diets is more challenging