Combining isotopic signatures of n(87Sr)/n(86Sr) and light stable elements (C, N, O, S) with multi-elemental profiling for the authentication of provenance of European cereal samples

The aim of this work (from the FP6 project TRACE) was to develop methods based on the use of geochemical markers for the authentication of the geographical origin of cereal samples in Europe (cf. EC regulations 2081/92 and 1898/06). For the first time, the potential usefulness of combining n(87Sr)/n(86Sr) and δ13C, δ15N, δ18O and δ34S isotopic signatures, alone or with key element concentrations ([Na], [K], [Ca], [Cu] and [Rb], progressively identified out of 31 sets of results), was investigated through multiple step multivariate statistics for more than 500 cereal samples collected over 2 years from 17 sampling sites across Europe representing an extensive range of geographical and environmental characteristics. From the classification categories compared (north/south; proximity to the Atlantic Ocean/to the Mediterranean Sea/to else; bed rock geologies) the first two were the most efficient (particularly with the ten variables selected together). In some instances element concentrations made a greater impact than the isotopic tracers. Validation of models included external prediction tests on 20% of the data randomly selected and, rarely done, a study on the robustness of these multivariate data treatments to uncertainties on measurement results. With the models tested it was possible to individualise 15 of the sampling sites

Strontium isotopic signatures of natural mineral waters, the reference to a simple geological map and its potential for authentication of food

This paper presents the investigation of strontium isotope ratios of about 650 different European natural mineral waters as part of the food traceability project "TRACE" funded by the EU. Analysed 87Sr/86Sr values in the natural mineral waters range from 0.7035 to 0.7777, which indicates an influence by a great diversity of rocks from young mantle derived basaltic rocks to very old silicic continental crust. The results of the large scale investigation are used to elaborate a novel spatial prediction for strontium isotope ratios by combining the measured data with a GIS based geological map of Europe. The resulting map can be used to predict the strontium isotopic composition of groundwater and thus the composition of bio-available strontium, which is available for uptake by plants and subsequently transferred into the food chain. We also show, as an example, that the strontium isotopic composition of honey and wheat from specific sample regions within the TRACE project correlates well with that of the natural mineral water as predicted by our map. The proof of principle shown in our paper is highly relevant for geographical food authentication as it allows an assessment of the origin of food products without the immediate need for geographically authenticated materials which may not always be available. Our approach provides a cost effective first instance screening tool