A tool to assure the geographical origin of local food products (glasshouse tomatoes) using labeling with rare earth elements

Multivariate Strategy for Understanding Soil Features from Rare-Earth Element Profiles: A Focus on Data Normalization

The interest in assessing the behavior of rare-earth elements (REE) in the natural environment is constantly increasing due to their numerous applications in both environmental and technological fields. However, current methodologies for analyzing REE distributions are based on normalization of REE concentration profiles to lithological values, potentially resulting in different outcomes depending on which lithological values are used for normalization, affecting the interpretability of the data. The present work proposes an alternative approach for analyzing REE concentration profiles by applying principal component analysis (PCA) to create REE chemometric maps. The data compression allows the visualization of the REE distribution using a red-green-blue (RGB) color scale (PC1 = red channel; PC2 = green channel; PC3 = blue channel) directly on a geographical map, reflecting the chemical properties of rare-earth elements. This highlights similarities and differences in the compositional REE distribution of natural soils, facilitating the interpretability of REE data and potentially leading to new insights related to seemingly unrelated samples. Additionally, PCA applied to soil variables correlates with REE patterns and provides deeper insights into soil properties in an unsupervised manner, enhancing the interpretation of soil characteristics and implementing the ability to monitor environmental changes and study soil evolution processes. Of particular significance is the fact that applying the proposed methodology to non-normalized data yields results that are consistent with those derived from normalized data sets. Therefore, this approach not only overcomes normalization challenges but also supports the classical approach from a new methodological perspective, paving the way for broader applications.

Authenticating teas using multielement signatures, strontium isotope ratios, and volatile compound profiling

High value food products are subject to adulterations and frauds. This study aimed to combine, in our knowledge for the first time, inorganic chemical tracers (multi-elements and Sr isotopy) with volatile organic compound (VOCs) to discriminate the geographic origin, the varieties and transformation processes to authenticate 26 tea samples. By measuring Sr isotope ratio using the multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), 6 out of 11 regions were successfully discriminated. The combination with the ICP-MS inorganic pattern allowed to discriminate 4 more regions with a significance level of 0.05. VOCs fingerprints, obtained with selected ion flow tube mass spectrometer (SIFT-MS), were not correlated with origin but with the cultivar and transformation processes. Green, oolong, and dark teas were clearly differentiated, with hexanal and hexanol contributing to the discrimination of oxidation levels. With this multi-instrumental approach, it is possible to certify the geographical origin and the tea conformity.

Authentication of meat and dairy products using rare earth element labeling and detection by solution based and laser ablation ICP-MS

In order to meet the increasing customer demand for local food products, various methods for verification of food origin by means of region specific trace element fingerprinting have been developed. However, for products from conventional agriculture, without a close relationship to the local soil, other methods for food authentication are required. In an alternative approach, foodstuffs produced in a certain region, by a specific producer or under certain conditions can be safeguarded against imitation by chemical labeling. The objective of the present study was to develop a method for labeling lamb meat and goat milk by selective enrichment of terbium and thulium in the feed for the animals. Therefore, a distinctive rare earth element (REE) pattern is artificially introduced which can be determined in labeled food products. Detection of REE labels was carried out using inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion. Alternatively, laser ablation ICP-MS (LA-ICP-MS) was applied, allowing direct analysis of bone samples and analysis of meat and milk samples after dry ashing and pressing pellets. After three weeks of administering 1000-fold terbium and thulium enriched feed to lambs, terbium and thulium enrichment was detected in all sample types except blood, following the trend bones > kidney > liver > heart > meat > kidney fat. Similarly, goat milk was successfully labeled after three weeks of feeding 500-fold terbium and thulium enriched feed. Hence, the present method allows discrimination of labeled from unlabeled animal products, while REE contents in all labeled products remained low enough to avoid any health risk for the consumer.

Production of fatty acid methyl esters and bioactive compounds from citrus wax

Citrus wax is a waste generated during the purification process of the citrus essential oil. A lot of citrus wax wastes are globally produced, despite this, its composition and properties are not well known. Here we present comprehensive results proving the chemical composition and the physical properties of citrus wax. Additionally, our study provides the basis for obtaining value-added products from citrus wax wastes. The qualitative/quantitative analysis revealed the presence of different compounds, which range from flavonoids, saponins, carbohydrates, unsaturated compounds, phenolic hydroxyls, and long-chain fatty acid esters. Given that citrus wax is a source of many bioactive compounds, they were preferably extracted with ethanol. The ethanolic extracts demonstrated the presence in citrus wax of different bioactives, such as 5-5'-dehydrodiferulic acid, 3,7-dimethylquercetin, 5,6-dihydroxy-7,8,3',4'-tetramethoxyflavone, tangeretin, and limonene. After the extraction of bioactives from citrus wax, a washed waxy material with high content of long-chain fatty acid esters was obtained. It was shown that this washed wax can be used for the production of biodiesel. The transesterification reactions in acid media was the preferred process because higher content of fatty acid methyl esters (such as hexadecanoic acid methyl ester and 9,12-octadecadienoic acid (Z,Z)-, methyl ester) were obtained. Currently, citrus wax does not have any industrial application, here we shown that under the concept of waste biorefinery, the citrus wax wastes are useful sources for producing value-added products such as bioactive compounds and biodiesel.

Rare Earth Element Labeling as a Tool for Assuring the Origin of Eggs and Poultry Products

Laying hens were fed terbium and thulium supplemented feed in order to introduce a distinctive rare earth element pattern that allows discrimination of labeled from unlabeled poultry products. Samples of egg yolk, egg shells, meat, bones, liver, blood, and feces were analyzed using either conventional or laser ablation inductively coupled plasma mass spectrometry. Already after a short time of administering supplemented feed, terbium and thulium enrichment could be unambiguously detected in the products, while absolute terbium and thulium contents remained low enough to ensure safety for the customer. This method could potentially be applied to specifically label foodstuffs produced in certain regions or under certain conditions, in order to ensure food authenticity.