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.

NMR-based identification of thickeners in membrane-filtered food premixtures

Premixtures for food production are complex mixtures typically containing thickeners due to their water binding capacity. Here, we report an improved protocol for the fast identification of food thickeners by 1H-NMR spectroscopy. The method is based on four steps: (i) dissolving of the dry premixture in water, (ii) centrifugation of the solution using centrifugal concentrators with a cut-off of 100 kDa, (iii) re-dissolving of the freeze-dried filtrate and the filter residue in small volumes of deuterated water, respectively, and (iv) 1H-NMR analysis of these fractions focusing on specific marker signals. Using this procedure, the high molecular weight thickeners (above 100 kDa) ĸ-carrageenan, galactomannans, gum arabic and pectin were unequivocally identified in the NMR spectra of the filter residues from different premixtures, whereas low molecular substances (below 100 kDa) including sucrose and glucose were determined in the filtrates.

Graphical abstract

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.

Anthocyanin- and proanthocyanidin-rich extracts of berries in food supplements--analysis with problems

The fundamental nutritional benefit of fruit and vegetables in the prevention of degenerative diseases--especially in the light of the current "anti-aging wave"--has directed the attention of scientists and consumers to a variety of berry fruits and their constituents. Many of these fruits, e.g. blueberries, elderberries or cranberries, have a long tradition in European and North American folk medicine. Based on these experiences and due to the growing interest the number of food supplements on the market containing fruit powders, juice concentrates or extracts of these fruits has increased considerably. Advertising for these products mainly focusses on the phenolic compounds, especially the anthocyanins and proanthocyanidins and their preventive effects. Most of the preparations are combinations, e.g. of extracts of different fruits with vitamins and trace elements, etc. which are labelled in a way which does not allow a comparison of the products. Typically, information on the extraction solvent, the drug: extract ratio and the content of anthocyanins and proanthocyanidins is missing. Besides that, the analysis of these polyphenols causes additional problems. Whereas the quality control of herbal medicinal products is regulated in detail, no uniform requirements for food supplements are existing. A broad spectrum of methods is used for the assay of the constituents, leading to differing, incomparable results. In addition to that, the methods are quite interference-prone and consequently lead to over- or underestimation of the contents. This publication provides an overview of some selected berries (lingonberry, cranberry, black elderberry, black chokeberry, black currant, blueberry), their constituents and use. The analytical methods currently used for the identification and quantification of the polyphenols in these berries are described, including an evaluation of their advantages and disadvantages.

Multi-element (H,C,N,S) stable isotope characteristics of lamb meat from different European regions

Multi-element (H,C,N,S) stable isotope ratio analysis was tested for its suitability as a means for geographical provenance assignment of lamb meat from several European regions. The defatted dry matter (crude protein fraction) from lamb meat was found to be a suitable probe for "light" element stable isotope ratio analysis. Significant differences were observed between the multi-element isotope ratios of lamb samples from different regions. The mean hydrogen isotopic ratios of the defatted dry matter from lamb were found to be significantly correlated with the mean hydrogen isotopic ratios of precipitation and groundwater in the production regions. Carbon and nitrogen isotopic ratios were influenced by feeding practices and climate. Sulfur isotopic ratios were influenced by geographical location and surface geology of the production region. The results permitted differentiation of lamb meat, from most production regions, by inspection. However, more sophisticated evaluation of the data using multivariate methods, such as linear discriminant analysis, achieved 78% correct classification.

Accuracy in equianalgesic dosing. conversion dilemmas

The clinical benefit and increased application of opioid rotation has focused attention on efficacy differences between opioids and their respective equianalgesic dose ratios. Understanding the differences between the opioids is critical to understanding their equianalgesic dose ratios and for adjusting therapy following rotation to a new analgesic. The purpose of this article is to describe controversies regarding the relative potencies of these agents as presented in current equianalgesic charts and to provide pharmacologic information to assist the clinician with opioid rotation.