Stuttgart, Germany

The Deutsche Forschungsanstalt für Segelflug, or DFS was formed in 1933 to centralise all gliding activity in Germany, under te directorship of Professor Georgii. It was formed by the nationalisation of the Rhön-Rossitten Gesellschaft at Darmstadt.The DFS was involved in producing training sailplanes for the Hitler Youth and Luftwaffe, as well as conducting research into advanced technologies such as flying wings and rocket propulsion. Notable DFS-produced aircraft include the DFS 230 transport glider , the German counterpart to the British Airspeed Horsa glider, and the DFS 194 forerunner of the famous Messerschmitt Me 163 rocket fighter.In 1938, following a fatal accident at the Wasserkuppe, DFS held a competition to design a more effective speed brake for gliders. The final design, produced by Wolfgang and Ulrich Hütter of Schempp-Hirth, is used to this day and generally referred to as the "Schempp-Hirth brake". ) Wikipedia.


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A stable isotope dilution assay was developed for quantitation of 4-methyl-4-sulfanylpentan-2-one (4MSP) in hops. The approach included the use of 4-(13C)methyl-4-sulfanyl(1,3,5-13C3)pentan-2-one as internal standard, selective isolation of hop thiols by mercurated agarose, and GC×GC-TOFMS analysis. Application of the method to 53 different hop samples revealed 4MSP concentrations between <1 and 114 μg/kg. Notably high concentrations were associated with United States varieties such as Citra, Eureka, Simcoe, and Apollo, whereas 4MSP was absent from traditional German and English varieties. Further experiments showed that besides the variety, also harvest year and storage vitally influenced 4MSP concentrations, whereas the impact of provenance was less pronounced. Hop processing such as drying and pelletizing had only a minor impact on 4MSP concentrations. Like the majority of other hop volatiles, 4MSP is predominantly located in the lupulin glands. © 2017 American Chemical Society.


Steinhaus M.,German Research Center for Food Chemistry
Journal of Agricultural and Food Chemistry | Year: 2017

The most odor-active compounds previously identified by application of an aroma extract dilution analysis were quantitated in freshly picked curry leaves, either by stable isotope dilution assays in combination with GC-GC-MS or by GC-FID after simultaneous extraction/fractionation. Odor activity values (OAVs) were calculated as ratios of concentrations to odor threshold values. The topmost OAVs were obtained for (3Z)-hex-3-enal (grassy; OAV 180 000), (1S)-1-phenylethane-1-thiol (sulfury, burnt; OAV 150 000), (1R)-1-phenylethane-1-thiol (sulfury, burnt; OAV 120 000), (3R)-linalool (citrusy; OAV 58 000), and myrcene (geranium leaf-like; OAV 23 000). The high OAVs calculated for its enantiomers confirmed 1-phenylethane-1-thiol as character impact compound of the typical sulfury and burnt aroma of curry leaves. The 1-phenylethane-1-thiol concentration in curry leaves decreased upon tissue disruption and drying, as well as upon frying of fresh leaves. By contrast, frying of dried leaves led to an increase of 1-phenylethane-1-thiol, indicating a yet unknown thermolabile precursor. © 2017 American Chemical Society.


Poehlmann S.,TU Munich | Schieberle P.,TU Munich | Schieberle P.,German Research Center for Food Chemistry
Journal of Agricultural and Food Chemistry | Year: 2013

Application of the aroma extract dilution analysis on a distillate prepared from an authentic Styrian pumpkin seed oil followed by identification experiments led to the characterization of 47 odor-active compounds in the flavor dilution (FD) factor range of 8-8192 among which 2-acetyl-1-pyrroline (roasty, popcorn-like), 2-propionyl-1-pyrroline (roasty, popcorn-like), 2-methoxy-4-vinylphenol (clove-like), and phenylacetaldehyde (honey-like) showed the highest FD factors. Among the set of key odorants, 2-propionyl-1-pyrroline and another 20 odorants were identified for the first time as constituents of pumpkin seed oil. To evaluate the aroma contribution in more detail, 31 aroma compounds showing the highest FD factors were quantitated by means of stable isotope dilution assays. On the basis of the quantitative data and odor thresholds determined in sunflower oil, odor activity values (OAV; ratio of concentration to odor threshold) were calculated, and 26 aroma compounds were found to have an OAV above 1. Among them, methanethiol (sulfury), 2-methylbutanal (malty), 3-methylbutanal (malty), and 2,3-diethyl-5- methylpyrazine (roasted potato) reached the highest OAVs. Sensory evaluation of an aroma recombinate prepared by mixing the 31 key odorants in the concentrations as determined in the oil revealed that the aroma of Styrian pumpkin seed oil could be closely mimicked. Quantitation of 11 key odorants in three commercial pumpkin seed oil revealed clear differences in the concentrations of distinct odorants, which were correlated with the overall aroma profile of the oils. © 2013 American Chemical Society.


Kiefl J.,German Research Center for Food Chemistry | Schieberle P.,German Research Center for Food Chemistry
Journal of Agricultural and Food Chemistry | Year: 2013

The majority of the world hazelnut crop is roasted, thus developing a unique aroma that depends on the cultivar used and on the roasting conditions applied. Although several studies have investigated the volatile fraction of different cultivars and have correlated the data with overall sensory profiles, studies establishing a correlation between key odorants among the bulk of odorless volatiles and the respective aroma profiles are not yet available. On the basis of recently published stable isotope dilution assays (SIDAs) using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOF-MS), differences in concentrations of key odorants in different hazelnut cultivars roasted under defined conditions were monitored and compared with sensory data obtained by projective mapping, aroma profile analysis, and triangle tests. The results showed that the aroma-active compounds 2-acetyl-1-pyrroline, 2-propionyl-1-pyrroline, 5-methyl-(E)-2-hepten-4-one, 2,3-diethyl-5-methylpyrazine, 3,5-dimethyl-2-ethylpyrazine, and 2-furfurylthiol are appropriate marker odorants to differentiate the various nut aromas. In particular, the appreciated roasty, nutty aroma of optimally roasted hazelnuts was developed if both 5-methyl-(E)-2-hepten-4-one and 3-methyl-4-heptanone were >450 μg/kg, whereas the sum of the two 2-acyl-1-pyrrolines and two pyrazines should not exceed 400 μg/kg to avoid an over-roasted smell. Such a desired aroma can be obtained for each cultivar, but obviously specific roasting times, temperatures, and roasting techniques had to be applied. © 2013 American Chemical Society.


Kiefl J.,German Research Center for Food Chemistry | Pollner G.,German Research Center for Food Chemistry | Schieberle P.,German Research Center for Food Chemistry
Journal of Agricultural and Food Chemistry | Year: 2013

Comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) has been used a few times to identify and quantitate single aroma-active compounds, but the capability of this technique to monitor a complete set of key odorants evoking the aroma of a given food in one run has not been exploited so far. A fast, multiodorant analysis using GC×GC-TOF-MS in combination with stable isotope dilution assays (SIDA) was developed to quantitate the entire set of aroma compounds, the sensometabolome, of raw and roasted hazelnuts (Corylus avellana L. 'Tonda Gentile') previously established by GC-olfactometry. The capability of the method to evaluate the aroma contribution of each sensometabolite was evaluated by introducing a new term, the limit of odor activity value (LOAV), indicating whether a given aroma compound can be determined down to an odor activity value (OAV) of 1 (odor activity value = ratio of concentration to odor threshold). The advantage of the new method was proven by comparing the performance parameters with a traditional one-dimensional approach using GC-ion trap mass-spectrometry (GC-IT-MS). The results showed that the detector linearity and sensitivity of GC×GC-TOF-MS was on average higher by a factor of 10 compared to GC-IT-MS, thus enabling the quantitation of the aroma relevant amounts of 22 key odorants of hazelnuts in one run of the 30 aroma-active compounds. Seven novel isotopically labeled internal standards were synthesized to meet the analytical requirements defined by electron impact ionization in TOF-MS, that is, to keep the label. On the basis of the quantitative results obtained, it was possible to closely mimic the aroma of raw and roasted 'Tonda Gentile' hazelnuts by preparing an aroma recombinate containing the key odorants at their natural concentrations occurring in the nuts. © 2013 American Chemical Society.


Lutz E.,German Research Center for Food Chemistry | Wieser H.,German Research Center for Food Chemistry | Koehler P.,German Research Center for Food Chemistry
Journal of Agricultural and Food Chemistry | Year: 2012

Disulfide bonds within gluten proteins play a key role in the breadmaking performance of wheat flour. In the present study, disulfide bonds of wheat gluten proteins were identified by using a new liquid chromatography-mass spectrometry (LC-MS) technique with alternating electron transfer dissociation (ETD)/collision-induced dissociation (CID). Wheat flour was partially hydrolyzed with thermolysin (pH 6.5, 37 °C, 16 h), and the digest was subjected to LC-MS with alternating ETD/CID fragmentation. Whereas CID provided peptide fragments with intact disulfide bonds, cleavage of disulfide bonds was preferred over peptide backbone fragmentations in ETD. The simultaneous observation of disulfide-linked and disulfide-cleaved peptide ions in the mass spectra not only provided distinct interpretation with high confidence but also simplified the conventional approach for determination of disulfide bonds, which often requires two separate experiments with and without chemical reduction. By application of the new method 14 cystine peptides were identified. Eight peptides confirmed previously established disulfide bonds within gluten proteins, and the other six cystine peptides were identified for the first time. One of the newly identified cystine peptides represented a "head-to-tail" cross-link between high molecular weight glutenin subunits. This type of cross-link, which has been postulated as an integral part of glutenin models published previously, has now been proven experimentally for the first time. From the six remaining cystine peptides interchain disulfide bonds between α-gliadins, γ-gliadins, and low molecular weight glutenin subunits were established. © 2012 American Chemical Society.


Babusyte A.,German Research Center for Food Chemistry | Kotthoff M.,German Research Center for Food Chemistry | Fiedler J.,German Research Center for Food Chemistry | Krautwurst D.,German Research Center for Food Chemistry
Journal of Leukocyte Biology | Year: 2013

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. © Society for Leukocyte Biology.


Steinhaus M.,German Research Center for Food Chemistry
Journal of Agricultural and Food Chemistry | Year: 2015

Curry leaves are a popular seasoning herb with a pronounced sulfury and burnt odor, the molecular background of which was yet unclear. Application of an aroma extract dilution analysis to the volatile fraction of curry leaves isolated by solvent extraction and solvent-assisted flavor evaporation afforded 23 odor-active compounds with flavor dilution (FD) factors ranging from 1 to 8192. On the basis of the comparison of their retention indices, mass spectra, and odor properties with data of reference compounds, the structures of 22 odorants could be assigned, 15 of which had not been reported in curry leaves before. Odorants with high FD factors included 1-phenylethanethiol (FD factor 8192), linalool (4096), α-pinene (2048), 1,8-cineole (1024), (3Z)-hex-3-enal (256), 3-(methylsulfanyl)propanal (128), myrcene (64), (3Z)-hex-3-en-1-ol (32), and (2E,6Z)-nona-2,6-dienal (32). The unique sulfury and burnt odor exhibited by 1-phenylethanethiol in combination with its high FD factor suggested that it constitutes the character impact compound of fresh curry leaf aroma. © 2015 American Chemical Society.


Krautwurst D.,German Research Center for Food Chemistry | Kotthoff M.,Fraunhofer Institute for Molecular Biology and Applied Ecology
Methods in Molecular Biology | Year: 2013

Smell is a multidimensional chemical sense. It creates a perception of our odorous environment by integrating the information of a plethora of volatile chemicals with other sensory inputs, emotions and memories. We are almost always exposed to odorant mixtures, not just single chemicals. Olfactory processing of complex odorant mixtures, such as coffee or wine, fi rst is decoded at the site of perception by the hundreds of different olfactory receptor types, each residing in the cilia of their olfactory sensory neurons in the nose. Often, only a few odorants from many are essential to determine complex olfactory perception. But merely using the chemical structure of odorants is insuf fi cient to identify and predict characteristic odor qualities and low odor thresholds. An understanding of odorant coding critically depends on knowledge about the interaction of key odorants of biologically relevant odor bouquets with their best cognate receptors. Here, we describe a hit map-based method of correlating the information content of all bioassay-tested odorants with their cognate odorant-receptor frequency in four phylogenetic subsets of human olfactory/chemosensory receptors. © Springer Science+Business Media, LLC 2013.


Wieser H.,German Research Center for Food Chemistry | Koehler P.,German Research Center for Food Chemistry
Journal of AOAC International | Year: 2012

Celiac disease (CD) is an inflammatory disease of the upper small intestine in genetically predisposed individuals caused by glutamine- and proline-rich peptides from cereal storage proteins (gluten) with a minimal length of nine amino acids. Such peptides are insufficiently degraded by gastrointestinal enzymes; they permeate the lymphatic tissue, are bound to celiac-specific, antigen-presenting cells, and stimulate intestinal T-cells. The typical clinical pattern is a flat small intestinal mucosa and malabsorption. Currently, the only therapy is a strict, lifelong gluten-free diet. Recent research has shown that gluten and gluten peptides can be degraded by prolyl endopeptidases from different sources. These peptidases can either be used to produce gluten-free foods from gluten-containing raw materials, or they have been suggested as an oral therapy for CD, in which dietary gluten is hydrolyzed by coingested peptidases already in the stomach, thus preventing CD-specific immune reactions in the small intestine. This would be an alternative for CD patients to the gluten-free diet. Furthermore, microbial transglutaminase could be used to detoxify gluten either by selectively modifying glutamine residues of intact gluten by transamidation with lysine methyl ester or by crosslinking gluten peptides in beverages via isopeptide bonds so that they can be removed by filtration. © 2012 Publishing Technology.

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