Characterization of Beef Coming from Different European Countries through Stable Isotope (H, C, N, and S) Ratio Analysis

Abstract

The need to guarantee the geographical origin of food samples has become imperative in recent years due to the increasing amount of food fraud. Stable isotope ratio analysis permits the characterization and origin control of foodstuffs, thanks to its capability to discriminate between products having different geographical origins and derived from different production systems. The Framework 6 EU-project "TRACE" generated hydrogen (²H/¹H), carbon (¹³C/¹²C), nitrogen (¹⁵N/¹⁴N), and sulphur (³⁴S/³²S) isotope ratio data from 227 authentic beef samples. These samples were collected from a total of 13 sites in eight countries. The stable isotope analysis was completed by combining IRMS with a thermal conversion elemental analyzer (TC/EA) for the analysis of δ(²H) and an elemental analyzer (EA) for the determination of δ(¹³C), δ(¹⁵N), and δ(³⁴S). The results show the potential of this technique to detect clustering of samples due to specific environmental conditions in the areas where the beef cattle were reared. Stable isotope measurements highlighted statistical differences between coastal and inland regions, production sites at different latitudes, regions with different geology, and different farming systems related to the diet the animals were consuming (primarily C3- or C4-based or a mixed one).

Keywords: authenticity; beef; food fraud; geographical origin; meat; stable isotope ratio analysis.

Figure 1

Correlation between annual δ(²H) of water at the beef sampling location estimated by the Water-Isotope database (Oxygen Isotopes in Precipitation Calculator) and the average δ(²H) values measured in the beef protein.

Figure 2

Plot showing the first two principal components (PC1 and PC2) determined from the analysis of beef protein δ(²H), δ(¹³C), δ(¹⁵N), and δ(³⁴S) values. The three groups considered are identified by different colors: C_LL_C4 (animals from coastal areas, sited at relatively low latitudes, given a C4-based diet (Barcelona, Chalkidiki, Sicily, and Tuscany)) in blue; C_ML_C3 (animals from coastal areas sited at higher latitudes compared to the other groups, given a C3-based diet (Cornwall, Orkney and Bohernagore)) in orange; I_LL_MIX (animals coming from inland areas sited at relatively low latitudes, given a mixed diet (Limousin, Frankonia, Allgäu, Gäuboden, Mühlviertel, and Trentino)) in grey.