The biocatalytic production of flavor naturals that determine chemosensory percepts of foods and beverages is an ever challenging target for academic and industrial research. Advances in chemical trace analysis and post-genomic progress at the chemistry-biology interface revealed odor qualities of nature's chemosensory entities to be defined by odorant-induced olfactory receptor activity patterns. Beyond traditional views, this review and meta-analysis now shows characteristic ratios of only about 3 to 40 genuine key odorants for each food, from a group of about 230 out of circa 10 000 food volatiles. This suggests the foodborn stimulus space has co-evolved with, and roughly match our circa 400 olfactory receptors as best natural agonists. This perspective gives insight into nature's chemical signatures of smell, provides the chemical odor codes of more than 220 food samples, and beyond addresses industrial implications for producing recombinants that fully reconstruct the natural odor signatures for use in flavors and fragrances, fully immersive interactive virtual environments, or humanoid bioelectronic noses.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are used in a wide range of products of all day life. Due to their toxicological potential, an emerging focus is directed towards their exposure to humans. This study investigated the PFAS load of consumer products in a broad perspective. Perfluoroalkyl sulfonic acids (C4, C6–C8, C10-PFSA), carboxylic acids (C4–C14-PFCA) and fluorotelomer alcohols (4:2, 6:2; 8:2 and 10:2 FTOH) were analysed in 115 random samples of consumer products including textiles (outdoor materials), carpets, cleaning and impregnating agents, leather samples, baking and sandwich papers, paper baking forms and ski waxes. PFCA and PFSA were analysed by HPLC-MS/MS, whereas FTOH were detected by GC/CI-MS. Consumer products such as cleaning agents or some baking and sandwich papers show low or negligible PFSA and PFCA contents. On the other hand, high PFAS levels were identified in ski waxes (up to about 2000 μg/kg PFOA), leather samples (up to about 200 μg/kg PFBA and 120 μg/kg PFBS), outdoor textiles (up to 19 μg/m2 PFOA) and some other baking papers (up to 15 μg/m2 PFOA). Moreover, some test samples like carpet and leather samples and outdoor materials exceeded the EU regulatory threshold value for PFOS (1 μg/m2). A diverse mixture of PFASs can be found in consumer products for all fields of daily use in varying concentrations. This study proves the importance of screening and monitoring of consumer products for PFAS loads and the necessity for an action to regulate the use of PFASs, especially PFOA, in consumer products.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-015-4202-7) contains supplementary material, which is available to authorized users.

Certain biogenic amines, such as 2-PEA, TYR, or T1AM, modulate blood pressure, cardiac function, brain monoaminergic systems, and olfaction-guided behavior by specifically interacting with members of a group of rhodopsin-like receptors, TAAR. A receptor that is absent from olfactory epithelia but had long been identified in the brain and a variety of peripheral tissues, TAAR1 has been found recently in blood B cells, suggesting a functional role of TAAR1 in these cells. With the present study, we have set out to clarify the expression and functional roles of TAAR in different isolated human blood leukocyte types. Here, we report the functional expression of TAAR1 and its closest relative TAAR2 in blood PMN and T and B cells. Both receptors are coexpressed in a subpopulation of PMN, where they are necessary for the chemosensory migration toward the TAAR1 ligands 2-PEA, TYR, and T1AM, with EC50 values of 0.43 ± 0.05 nM, 0.52 ± 0.05 nM, and 0.25 ± 0.04 nM, respectively. The same amines, with similar potencies, triggered cytokine or Ig secretion, in purified blood T or B cells, respectively. Notably, 2-PEA regulated mRNA expression of 28 T cell function-related genes, above all of the CCL5. In siRNA-guided experiments, TAAR1 and TAAR2 proved to be necessary for amine-induced blood leukocyte functions. In summary, our results demonstrate that biogenic amines potently regulate blood cell functions via TAAR1 and TAAR2 and open the perspective of their specific pharmacological modulation.

The detection of key food odorants appears to be an important capability of odorant receptors. Here, thiols occupy an outstanding position among the 230 known key food odorants because of their very low odor thresholds. Members of the homologous series of 3-mercapto-2-methylalkan-1-ols have been described as onion key food odorants or food constituents and are detected at logarithmically different thresholds. 3-Mercapto-2-methylpentan-1-ol being the only key food odorant within this series also has the lowest odor threshold. Most odorants typically activate combinations of odorant receptors, which may be narrowly or broadly tuned. Consequently, a specific receptor activation pattern will define an odor quality. In contrast, here we show that just 1 of the 391 human odorant receptors, OR2M3, responded exclusively to 3-mercapto-2-methylpentan-1-ol of the 190 key food odorants tested, with a half maximal effective concentration at submicromolar concentration. Moreover, neither the Denisovan OR2M3 nor the closest OR2M3 homologs from five species did respond to this compound. This outstanding specificity of extremely narrowly tuned human OR2M3 can explain both odor qualities and odor threshold trend within a homologous series of 3-mercapto-2-methylalkan-1-ols and suggests a modern human-specific, food-related function of OR2M3 in detecting a single onion key food odorant.

Bioconcentration factors (BCF) for regulatory purposes are usually determined by fish flow-through tests according to technical guidance document OECD 305. Fish bioconcentration studies are time consuming, expensive, and use many laboratory animals. The aim of this study was to investigate whether the freshwater amphipod Hyalella azteca can be used as an alternative test organism for bioconcentration studies. Fourteen substances of different hydrophobicity (log Kow 2.4–7.6) were tested under flow-through conditions to determine steady state and kinetic bioconcentration factors (BCFss and BCFk). The results were compared with fish BCF estimates for the same substances described in the literature to show the relationship between both values. Bioconcentration studies with the freshwater amphipod H. azteca resulted in BCF estimates which show a strong correlation with fish BCF values (r2 = 0.69). Hyalella BCF values can be assessed in accordance with the regulatory B criterion (BCF > 2000, i.e., REACH) and thereby enable the prediction of B or non-B classification in the standard fish test. Therefore, H. azteca has a high potential to be used as alternative test organism to fish for bioconcentration studies.Electronic supplementary materialThe online version of this article (10.1007/s11356-018-3677-4) contains supplementary material, which is available to authorized users.

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The group of per-and polyfluoroalkyl substances (PFAS) comprises thousands of chemicals, which are used in various industrial applications and consumer products. In this study, a feeding experiment with laying hens and feed grown on a contamination site was conducted, and PFAS were analyzed in the feed and eggs to assess the transfer of PFAS into eggs. A targeted analysis of perfluoroalkyl acids (PFAAs) and different sulfonamides was performed. Additionally, the total oxidizable precursor (TOP) assay was modified by fully oxidizing small amounts of the samples instead of oxidizing their extracts in order to overcome potential losses during extraction. Targeted analysis showed the presence of known PFAAs and four sulfonamides in the feed and egg yolk samples. In the plant-based feed, short-chain PFAAs, methyl and ethyl perfluorooctane sulfonamidoacetic acid (Me-and EtFOSAA), and perfluorooctane sulfonic acid (PFOS) were the most abundant PFAS. In the eggs, PFOS, FOSAA, and its alkylated homologues showed the highest concentrations. The TOP assay revealed the presence of substantial amounts of precursors with different chain lengths from C4 to C8. The highest relative increase of PFOA after oxidation was observed in egg yolk from the end of the exposure period (828%). The results of this study demonstrate the transfer of PFAAs and their precursors into hens' eggs and emphasize the contribution of (known and unidentified) precursors to the overall PFAS burden in edible products. The modified TOP assay approach was shown to be a powerful tool to better assess the total burden of samples with PFAS.

Per- and polyfluoroalkyl substances (PFAS) represent a versatile group of ubiquitously occurring chemicals of increasing regulatory concern. The past years lead to an ever expanding portfolio of detected anthropogenic PFAS in numerous products encountered in daily life. Yet no clear picture of the full range of individual substance that comprise PFAS is available and this challenges analytical and engineering sciences. Authorities struggle to cope with uncertainties in managing risk of harm posed by PFAS. This is a result of an incomplete understanding of the range of compounds that they comprise in differing products. There are analytical uncertainties identifying PFAS and estimating the concentrations of the total PFAS load individual molecules remain unknown. There are four major trends from the chemical perspective that will shape PFAS research for the next decade. Mobility: A wide and dynamic distribution of short chain PFAS due to their high polarity, persistency and volatility.Substitution of regulated substances: The ban or restrictions of individual molecules will lead to a replacement with substitutes of similar concern.Increase in structural diversity of existing PFAS molecules: Introduction of e.g., hydrogens and chlorine atoms instead of fluorine, as well as branching and cross-linking lead to a high versatility of unknown target molecules.Unknown “Dark Matter”: The amount, identity, formation pathways, and transformation dynamics of polymers and PFAS precursors are largely unknown.These directions require optimized analytical setups, especially multi-methods, and semi-specific tools to determine PFAS-sum parameters in any relevant matrix.