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Neufahrn bei Freising, Germany

Granvogl M.,TU Munich | Beksan E.,Deutsche Forschungsanstalt fur Lebensmittelchemie | Schieberle P.,TU Munich
Journal of Agricultural and Food Chemistry | Year: 2012

2-Substituted-5-methyl-3-oxazolines, a novel class of aroma precursors that are able to release the respective Strecker aldehydes by hydrolysis, were identified. Hydrolysis can take place after the addition of water or with human saliva during mastication, respectively. 2-Isobutyl-, 2-sec-isobutyl-, 2-isopropyl, and 2-benzyl-5-methyl-3-oxazolines were synthesized and structurally identified by means of gas chromatography-mass spectrometry (GC-MS) in the electron impact mode and in the chemical ionization mode as well as by one- and two-dimensional NMR experiments. With these compounds at hand, a variety of stability experiments were performed using headspace-GC-MS or proton transfer reaction-MS techniques on the basis of stable isotope dilution assays, proving the ability to release the respective Strecker aldehydes was dependent on the pH value as well as on the hydrolysis time. After the addition of water at 37 °C, for example, >70 mol % of 3-methylbutanal or >40 mol % of phenylacetaldehyde was liberated from a solution of 2-isobutyl-5-methyl-3- oxazoline or 2-benzyl-5-methyl-3-oxazoline, respectively, after 5 min. Furthermore, the presence of 2-isobutyl-5-methyl-3-oxazoline in dark chocolate containing 70% cocoa was proven by GC-MS. © 2012 American Chemical Society. Source


Harteneck C.,University of Tubingen | Klose C.,University of Tubingen | Krautwurst D.,Deutsche Forschungsanstalt fur Lebensmittelchemie
Advances in Experimental Medicine and Biology | Year: 2011

In humans, 27 TRP channels from 6 related families contribute to a broad spectrum of cellular functions, such as thermo-, pressure-, volume-, pain- and chemosensation. Pain and inflammation-inducing compounds represent potent plant and animal defense mechanisms explaining the great variety of the naturally occurring, TRPV1-, TRPM8-, and TRPA1-activating ligands. The discovery of the first vanilloid receptor (TRPV1) and its involvement in nociception triggered the euphoria and the hope in novel therapeutic strategies treating pain, and this clear-cut indication inspired the development of TRPV1-selective ligands. On the other hand the nescience in the physiological role and putative clinical indication hampered the development of a selective drug in the case of the other TRP channels. Therefore, currently only a handful of mostly un-selective blocker is available to target TRP channels. Nevertheless, there is an ongoing quest for new, natural or synthetic ligands and modulators. In this chapter, we will give an overview on available broad-range blocker, as well as first TRP channel-selective compounds. © 2011 Springer Science+Business Media B.V. Source


Grosshauser S.,Deutsche Forschungsanstalt fur Lebensmittelchemie | Schieberle P.,Deutsche Forschungsanstalt fur Lebensmittelchemie
Journal of Agricultural and Food Chemistry | Year: 2013

Application of aroma extract dilution analysis (AEDA) on the volatile fraction isolated from pan-fried white mushrooms (Agaricus bisporus L.) revealed 40 odor-active compounds in the flavor dilution (FD) factor range of 8-8192, among which the caramel-like smelling 4-hydroxy-2,5-dimethylfuran-3(2H)-one showed the highest FD factor of 8192, followed by 2-propionyl-1-pyrroline (popcorn-like) and 3-hydroxy-4,5-dimethylfuran-2(5H)-one (seasoning-like). A total of 36 compounds are reported for the first time in processed mushrooms, and 25 odorants showing the highest FD factors were then quantitated by stable isotope dilution assays and their odor activity values (OAVs) were calculated as ratio of their concentrations to their odor thresholds. Among them, 3-methylbutanal (malty), 3-(methylthio)propanal (cooked potato), and 2-acetyl-1-pyrroline (popcorn-like) showed the highest OAVs (>100) in the pan-fried mushrooms, followed by 1-octen-3-one, 2-propionyl-1-pyrroline, 4-hydroxy-2,5-dimethylfuran-3(2H)-one, phenylacetaldehyde, 2,3-diethyl-5- methylpyrazine, and 3-hydroxy-4,5-dimethylfuran-2(5H)-one with OAVs >10. An aqueous aroma recombinate containing 13 odorants (OAV > 1) in their actual concentrations in the fried mushrooms showed a good similarity to the original aroma profile. The quantitation of the key odorants in raw mushrooms, identified with high FD factors during the AEDA, revealed that numerous odorants were quantitatively changed by the frying process, but in particular the concentrations of 2-phenylacetaldehyde and 3-methylbutanal were higher by factors of ∼40 and 6, respectively, compared to the amounts in the processed mushrooms. The data suggested an enzymatic formation of both Strecker aldehydes by the cut mushroom tissue. In total, 26 odorants were newly identified in raw mushrooms. © 2013 American Chemical Society. Source


Langos D.,Deutsche Forschungsanstalt fur Lebensmittelchemie | Granvogl M.,TU Munich | Schieberle P.,Deutsche Forschungsanstalt fur Lebensmittelchemie | Schieberle P.,TU Munich
Journal of Agricultural and Food Chemistry | Year: 2013

Application of aroma extract dilution analysis (AEDA) on the volatiles isolated from a commercial Bavarian wheat beer (WB A) eliciting its typical aroma profile, best described by a clove-like, phenolic odor quality, revealed 36 odorants in the flavor dilution (FD) factor range from 16 to 4096. Among them, 2-methoxy-4-vinylphenol (clove-like) and 2-phenylethanol (flowery) showed the highest FD factors. AEDA of a second wheat beer (WB B), somewhat lacking the typical wheat beer odor note, revealed 32 odor-active components in the FD factor range from 32 to 8192. Among them, 2-phenylethanol, (E)-β- damascenone (cooked apple-like) and 3-methylbutanol (malty) were detected with the highest FD factors. Next, all odorants evaluated with an FD factor ≥32 were quantitated by stable isotope dilution assays in both beers, and the odor activity values (OAVs; ratio of concentration to odor threshold) were calculated. Thereby, ethanol, (E)-β-damascenone, 3-methylbutyl acetate, ethyl methylpropanoate, and ethyl butanoate showed the highest OAVs in WB A, followed by acetaldehyde, 3-methylbutanol, and dimethyl sulfide. In WB B, ethanol, (E)-β-damascenone, ethyl methylpropanoate, ethyl butanoate, and 3-methylbutyl acetate showed the highest OAVs. Whereas most aroma compounds were present in the same order of magnitude in both beer samples, in particular, 2-methoxy-4-vinylphenol and 4-vinylphenol (smoky, leather-like) were by factors of 13 and 15, respectively, higher in WB A. For the first time, the overall aroma of wheat beer (WB A) was successfully simulated on the basis of 27 reference compounds in their natural concentrations using water/ethanol (95:5; v/v) as the matrix. © 2013 American Chemical Society. Source


Seideneck R.,Deutsche Forschungsanstalt fur Lebensmittelchemie | Schieberle P.,Deutsche Forschungsanstalt fur Lebensmittelchemie
European Food Research and Technology | Year: 2011

Application of a comparative aroma extract dilution analysis on a hand-squeezed (juice A) and an industrially squeezed, unpasteurised orange juice (juice B), revealed qualitatively almost the same set of odour-active compounds. However, while in juice A, vanillin, ethyl butanoate, wine lactone, (Z)-3-hexenal, (S)-ethyl 2-methylbutanoate and (S)-linalool were detected with the highest flavour dilution (FD) factors, in juice B prepared by means of an FMC extractor, several compounds, like (R)-limonene, (R)-α-pinene and octanal showed higher FD factors, in addition to ethyl butanoate, wine lactone and (S)-ethyl 2-methylbutanoate. Quantification of seventeen odorants in both juices by means of stable isotope dilution assays followed by a calculation of odour activity values (OAV; ratio of concentration to odour threshold) revealed a clear change in the ranking order: while (S)-ethyl 2-methylbutanoate, (R)-limonene, (Z)-3-hexenal and linalool were first in rank among the odorants of juice A, in juice B, (R)-limonene and (S)-linalool followed by (S)-ethyl 2-methylbutanoate showed the highest OAVs. Sensory experiments revealed that the much higher concentrations of the seven peel oil constituents, and the lack in (Z)-3-hexenal, are the reason for the aroma differences observed for both juices. Further experiments indicated that lowering the pressure during commercial juicing, and also the avoidance of a freezing/thawing process could be helpful in getting closer to the aroma of hand-squeezed orange juice, because peel oil constituents are lowered and, in particular, the latter procedure leads to a complete degradation of (Z)-3-hexenal. © 2011 Springer-Verlag. Source

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