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Pollner G.,Deutsche Forschungsanstalt For Lebensmittelchemie Leibniz Institute | Schieberle P.,Deutsche Forschungsanstalt For Lebensmittelchemie Leibniz Institute
Journal of Agricultural and Food Chemistry | Year: 2016

By application of aroma extract dilution analysis (AEDA) on the volatile fraction isolated from commercial cold-pressed rapeseed oil prepared from unpeeled seeds, 35 odor-active constituents in the flavor dilution (FD) factor range of 8-8192 were detected. The identification experiments showed that the earthy, pea-like-smelling 2-isopropyl-3-methoxypyrazine showed the highest FD factor of 8192, followed by 1-octene-3-one (FD 4096) and (E,Z)-2,6-nonadienal with an FD of 2048. After quantitation of the 16 key odorants showing FD factors ≥32 by stable isotope dilution assays and a determination of their odor thresholds in deodorized sunflower oil, odor activity values (OAV; ratio of concentration to odor threshold) could be calculated. The results indicated 2-isopropyl-3-methoxypyrazine, (E,E)-2,4-nonadienal (deep-fried, fatty), and (E,Z)-2,6-nonadienal (cucumber-like) with the highest OAVs. To confirm that the key aroma compounds were correctly identified and quantitated, a recombination experiment was performed by mixing the reference odorants in the same concentrations as they occurred in the rapeseed oil using odorless sunflower oil as the matrix. The recombinate showed a very good agreement with the overall aroma of the oil. In a commercial rapeseed oil prepared from peeled seeds, the same odorants were identified; however, in particular, the FD factor of dimethyl sulfide (DMS) was clearly higher. Quantitation of DMS in 10 commercial rapeseed oils from either peeled and unpeeled seeds revealed significant differences in DMS, but no influence of the peeling process on the amounts of DMS was found. The data can serve as a basis for the quality assessment of cold-pressed rapeseed oil. © 2015 American Chemical Society.

Malki A.,Deutsche Forschungsanstalt For Lebensmittelchemie Leibniz Institute | Fiedler J.,Deutsche Forschungsanstalt For Lebensmittelchemie Leibniz Institute | Fricke K.,Deutsche Forschungsanstalt For Lebensmittelchemie Leibniz Institute | Ballweg I.,TU Munich | And 2 more authors.
Journal of Leukocyte Biology | Year: 2015

Our cellular immune system has to cope constantly with foodborne substances that enter the bloodstream postprandially. Here, they may activate leukocytes via specific but yet mostly unknown receptors. Ectopic RNA expression out of gene families of chemosensory receptors, i.e., the;400 ORs,;25 TAS2R bitter-taste receptors, and the TAS1R umami- and sweet-taste receptor dimers by which we typically detect foodborne substances, has been reported in a variety of peripheral tissues unrelated to olfaction or taste. In the present study, we have now discovered, by gene-specific RTPCR experiments, the mRNA expression of most of the Class I ORs (TAS1R) and TAS2R in 5 different types of blood leukocytes. Surprisingly, we did not detect Class II OR mRNA. By RT-qPCR, we show the mRNA expression of human chemosensory receptors and their cow orthologs in PMN, thus suggesting an evolutionary concept. By immunocytochemistry, we demonstrate that some olfactory and taste receptors are expressed, on average, in 40–60% of PMN and T or B cells and largely coexpress in the same subpopulation of PMN. The mRNA expression and the size of subpopulations expressing certain chemosensory receptors varied largely among individual blood samples, suggesting a regulated expression of olfactory and taste receptors in these cells. Moreover, we show mRNA expression of their downstream signaling molecules and demonstrate that PTX abolishes saccharin- or 2-PEA-induced PMN chemotactic migration, indicating a role for Gi-type proteins. In summary, our data suggest "chemosensory"- type subpopulations of circulating leukocytes. © Society for Leukocyte Biology.

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