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

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).

MALDI mass spectrometry imaging: From constituents in fresh food to ingredients, contaminants and additives in processed food.

Mass Spectrometry imaging (MS imaging) provides spatial information for a wide range of compound classes in different sample matrices. We used MS imaging to investigate the distribution of components in fresh and processed food, including meat, dairy and bakery products. The MS imaging workflow was optimized to cater to the specific properties and challenges of the individual samples. We successfully detected highly nonpolar and polar constituents such as beta-carotene and anthocyanins, respectively. For the first time, the distributions of a contaminant and a food additive were visualized in processed food. We detected acrylamide in German gingerbread and investigated the penetration of the preservative natamycin into cheese. For this purpose, a new data analysis tool was developed to study the penetration of analytes from uneven surfaces. Our results show that MS imaging has great potential in food analysis to provide relevant information about components' distributions, particularly those underlying official regulations.

Fast Identification of Food Thickeners by Nontargeted NMR-Spectroscopy.

Food thickeners are carbohydrate additives that can only be determined by long-term, multistep analysis. Fast methods to directly determine thickeners in food matrixes are therefore welcome. In this study, a rapid procedure based on the direct 1H NMR analysis of food samples dissolved in deuterated water was developed. Individual thickeners were assigned due to specific marker signals gleaned from two-dimensional NMR analyses. The combination of one-dimensional 1H NMR and DOSY experiments enabled unequivocal assignments of thickeners even in complex matrixes. Using this approach, gum arabic, carrageenan, agar-agar, galactomannans, and pectin could be identified in pastille, glaze, and fruit spread. Because of low concentrations (<0.5%-1%, w/w), the same thickeners and others such as xanthan gum and alginate could not be determined directly by NMR in curry sauce, rice pudding, choco milk drink, and lemon peel flavor. Moreover, NMR analyses of the hydrolysate did not reveal the specific monomeric units of the thickeners under study, as shown for the hydrolysate of lemon peel flavor. Nevertheless, the NMR approach could provide welcome means in the future to directly determine intact thickeners in food.

Isotopic and elemental data for tracing the origin of European olive oils.

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.