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).

Die Stabilisotopenanalyse ist ein effizientes Verfahren in der Authentizitätsprüfung von Lebensmitteln. Mit ihr kann ein Etikettenschwindel bezüglich verwendeter Rohstoffe, verwendeter erlaubter und unerlaubter Zusätze erkannt und damit Verfälschungen nachgewiesen werden. Eine Bestimmung der geografischen Herkunft mittels Stabilisotopenanalyse ist möglich, wenn sich die Isotopenverhältnisse der geografischen Herkünfte deutlich voneinander unterscheiden und wenn eine ausreichende Anzahl von Vergleichsdaten authentischer Erzeugnisse oder verlässlicher Handelsproben vorliegt. Aufgrund der zunehmenden Qualität von Verfälschungen ist eine ständige Weiterentwicklung der Isotopenmethoden erforderlich.

This chapter summarizes terms, definitions, and reference materials used for stable isotope ratio analysis (SIRA) of the bioelements hydrogen, carbon, and oxygen. The principles of biotic and abiotic fractionation in biomolecules like flavor compounds are explained. A short review of the common methods for the determination of isotope ratios H-2/H-1, C-13/C-12, and O-18/O-16, using isotope ratio mass spectrometry (IRMS) and nuclear magnetic resonance spectrometry (NMR) of hydrogen and carbon (H-2- and C-13-NMR) are introduced. Further the focus is set on selected applications of authentication control of flavor compound and flavorings using isotope ratio analysis. Examples of benzaldehyde, vanillin, vanilla flavorings and vanilla extracts, butanoic acid, isoprenoids, and essential oils as well as fruity flavor compounds like gamma- and delta-lactones are presented. Potentials and limitations of SIRA are discussed taking the analytical requirements into consideration, as well as representative databases and suitable guidelines for authenticity assessment.

Multiple stable isotope ratios (δ2H, δ13C, δ18O and δ34S) were measured in muscle, muscle lipids and lipid fractions collected from 28 lambs, subjected to a diet-switch and raised on two energy allowances (EAs), to determine tissue turnover and diet-tissue fractionation. The diet-muscle fractionations prior to the diet-switch were estimated to be −44.0‰, +1.9‰ and 0‰ for H, C and S, respectively, while the drinking water was demonstrated to be the main source of muscle O and thus δ18O variation. The diet-intra-muscular lipid fractionations prior to the diet-switch were estimated to be −172.7‰, −1.3‰ and −11.5‰ for H, C and O, respectively. The C half-lives of muscle were determined to be 75.7 and 91.6days for animals receiving the high and low EA, respectively. Extracting temporally resolved pre-slaughter dietary information from meat by analysing bulk muscle, muscle lipids and muscle lipid fractions appeared to be not practicable due to possible incomplete turnover of lipids.

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(Sr-87)/n (Sr-86) and delta C-13, delta N-15, delta O-18 and delta S-34 isotopic signatures, alone or with key element concentrations ([Na], In [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. (C) 2010 Elsevier Ltd. All rights reserved.

The aim of this study as a part of the food traceability project “TRACE” funded by the EU was to investigate if honeys produced in regions with different climatic and geological characteristics could be discriminated on the basis of the isotopic data. The hydrogen, carbon, nitrogen and sulphur stable isotope ratios of 516 authentic honeys from 20 European regions are presented and discussed. As honey contains only small quantities of nitrogen and sulphur, the honey protein was precipitated in order to obtain measurable amounts of these elements. The mean hydrogen isotopic ratios of the honey protein were found to be significantly correlated with the mean hydrogen isotopic ratios of precipitation and groundwater in the production regions. Carbon isotopic ratios were influenced by climate. The sulphur stable isotope composition is clearly influenced by geographical location (sea spray effect) and surface geology of the production regions. The results show that the stable isotope ratios of the four bio-elements carbon, nitrogen, hydrogen and sulphur in honey protein can be applied to verify the origin of honey. Carbon and sulphur were identified by canonical discriminant analysis as providing the maximum discrimination between honey samples. For seven regions the percentage of correct classified samples is greater than 70%. It was concluded that the methodology in its current state can be used to provide reliable origin information.

H, C, and O stable isotope ratios and the elemental profile of 267 olive oils and 314 surface waters collected from 8 European sites are presented and discussed. The aim of the study was to investigate if olive oils produced in areas with different climatic and geological characteristics could be discriminated on the basis of isotopic and elemental data. The stable isotope ratios of H, C, and O of olive oils and the ratios of H and O of the relevant surface waters correlated to the climatic (mainly temperature) and geographical (mainly latitude and distance from the coast) characteristics of the provenance sites. It was possible to characterize the geological origin of the olive oils by using the content of 14 elements (Mg, K, Ca, V, Mn, Zn, Rb, Sr, Cs, La, Ce, Sm, Eu, U). By combining the 3 isotopic ratios with the 14 elements and applying a multivariate discriminant analysis, a good discrimination between olive oils from 8 European sites was achieved, with 95% of the samples correctly classified into the production site.