Application of multiple stable isotopes to aid identification of the origin of regional and organic animal products in Hesse, Germany.

There is an increasing global demand for regional and organic produce. However, the growth of these markets depends on consumers' trust. Thus, novel methods must be developed to aid the verification of the origin of produce. We built on our previous study to identify the geographical origin and production method of animal-derived food products. Thirty-samples of eggs, 99 of milk, 34 of beef, and 62 of pork were collected from different regions in central Germany and analysed for their stable isotopic composition. The analysis followed a single-variate authentification approach using five isotope signatures, δ¹⁸O, δ²H, δ¹³C, δ¹⁵N, and δ³⁴S. The best-performing indicators for verification of the geographical origin were δ¹⁵N and δ³⁴S for beef; δ¹⁸O, δ²H, and δ¹³C for milk, and δ²H and δ¹³C for pork. These tracers indicated statistically significant differences among regions with the exception of pork; the results recorded for eggs were inconclusive. It was possible to distinguish between production methods by means of δ¹⁵N and δ³⁴S (beef); all five tracers (eggs), and δ¹³C, δ¹⁵N, and δ³⁴S (milk). This study demonstrated how the analysis of stable isotopes can be employed to determine the geographic region of origin and production method of animal-derived products in Germany.