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Hexanoic Acid (hexanoic + acid)
Selected AbstractsThe Biosynthesis of 3-(trans -2-Nitrocyclopropyl)alanine, a Constituent of the Signal Metabolite HormaomycinEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2005Melanie Brandl Abstract Feeding experiments with Streptomyces griseoflavus using deuterium-labeled racemic 3,3-[D2]- (6b), 4,4-[D2]- (6c), 5,5-[D2]- (6d), and 6,6-[D2]-lysine (6e), and 3-amino-5-(2-amino-1,1-dideuterioethyl)-4,5-dihydrofuran-2-one dihydrochloride (34·2HCl) were carried out in order to obtain detailed information about the hitherto unknown biosynthetic pathway from lysine to the unusual amino acid 3-(trans -2,-nitrocyclopropyl)alanine [(3-Ncp)Ala] (2), which is a building block of hormaomycin 1a. The corresponding lysine dihydrochlorides were prepared in 33, 24, 19, and 30% overall yield, respectively, along a new efficient general synthetic route applying an alkylation of the lithium enolate of O,Donnel's glycine equivalent 7 as a key step. In the attempted preparation of 5,5-[D2]-4-hydroxylysine (29), the respective ,-lactone (34·2 HCl) was obtained in five steps with 10% overall yield. The distribution of isotope labels in hormaomycins 1b,d led to the formulation of a reasonable cyclization mechanism of 2-amino-4-hydroxy-6-(hydroxyimino)hexanoic acid, an ,-oxime analogue of 4-hydroxylysine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Odour-active compounds of Jinhua hamFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2008Huanlu Song Abstract Using DHS, SAFE, GC,O and GC,MS, the odour-active compounds of Jinhua ham were identified and ranked according their odour potencies. For DHS, the ham powder was purged with a nitrogen stream at a flow rate of 50 ml/min for 25 min, 5 min and 1 min, respectively. The effluent of sample headspace was trapped by a Tenax tube, which was placed onto the vessel for GC,O. The most important odorants (FD factor = 125) in Jinhua ham headspace were ethyl 2-methylbutanoate/ethyl 3-methylbutanoate, hexanal, 1-hexen-3-one, 1-octen-3-one, 2-acetyl-1-pyrroline and 2-methoxyphenol, followed by the following odorants (FD factor = 25): 3-methyl butanal, dimethyl trisulphide, 1-nonen-3-one, butanoic acid, phenylacetaldehyde, 3-methylbutanoic acid, 2-methyl(3-methyldithio)furan, , -nonalctone and 4-methylphenol (p -cresol). For SAFE, the ham powder was extracted with diethyl ether, distilled by SAFE and then separated into neutral/basic and acidic fractions. Both fractions were subjected to AEDA. The relatively high-odour impact compounds (Log3FD Factor ,5) of the N/B fraction of SAFE extract of Jinhua ham were 1-octen-one, ethyl 3-methylbutanoate, methional, phenylacetaldehyde, 2-phenylethanol, (E)-4,5-epoxy-(E)-decenal, p -cresol (4-methylphenol); 3-methylbutanal, hexanal, 2-acetyl-1-pyrroline, decanal, (E,Z)-2,6-nonadienal and (E,E)-decadienal. The important odorants of the Ac fraction of SAFE extract of Jinhua ham were butanoic acid, 3-methylbutanoic acid, hexanoic acid, phenylacetic acid and an unknown. It was shown that the aroma of Jinhua ham consisted of a variety of compounds having different odour properties; a single compound could not characterize the aroma of Jinhua ham. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of the aroma impact compounds in heated sweet cream butterFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2003D. G. Peterson Abstract This study was conducted to determine which volatile compounds are primarily responsible for the aroma of heated sweet cream butter. Static headspace analysis was used for aroma isolation and gas chromatography,olfactometry (GC,O) for the selection of odour-active components. Quanti,cation of selected odourants was done via purge and trap-GC/mass spectrometry (MS). Nineteen odour-active compounds were detected in the headspace (static) of heated butter (hydrogen sulphide, methanethiol, acetaldehyde, 2,3-butanedione, 1-hexen-3-one, butanoic acid, 3-methylbutanoic acid, 2-heptanone, methional, dimethyl trisulphide, 1-octen-3-one, hexanoic acid, furaneol, , -hexanolactone, nonanal, (E)-2-nonenal, , -octanolactone, skatole and , -decanolactone). Aroma recombination studies followed by sensory analysis indicated that the aroma of our heated butter model was rated the same (similarity) as a heated commercial butter (obtained from local market) in comparison to a heated freshly manufactured butter. The aroma of a heated commercial unsalted butter and a heated butter aroma model of Budin 1 also were signi,cantly less similar than the aroma of our heated butter model in comparison to a heated freshly manufactured butter. Copyright © 2003 John Wiley & Sons, Ltd. [source] Aroma Components of American Country HamJOURNAL OF FOOD SCIENCE, Issue 1 2008H. Song ABSTRACT:, The aroma-active compounds of American country ham were investigated by using direct solvent extraction-solvent assisted flavor evaporation (DSE-SAFE), dynamic headspace dilution analysis (DHDA), gas chromatography-olfactometry (GCO), aroma extract dilution analysis (AEDA), and gas chromatography-mass spectrometry (GC-MS). The results indicated the involvement of numerous volatile constituents in the aroma of country ham. For DHDA, 38 compounds were identified as major odorants, among them, 1-octen-3-one, 2-acetyl-1-pyrroline, 1-nonen-3-one, decanal, and (E)-2-nonenal were the most predominant, having FD-factors , 125 in all 3 hams examined, followed by 3-methylbutanal, 1-hexen-3-one, octanal, acetic acid, phenylacetaldehyde, and FuraneolÔ. For the DSE-SAFE method, the neutral/basic fraction was dominated by 1-octen-3-one, methional, guaiacol, (E)-4,5-epoxy-(E)-decenal, p-cresol as well as 3-methylbutanal, hexanal, 2-acetyl-1-pyrroline, phenylacetaldehyde, and ,-nonalactone. The acidic fraction contained mainly short-chain volatile acids (3-methylbutanoic acid, butanoic acid, hexanoic acid, and acetic acid) and Maillard reaction products (for example, 4-hydroxy-2,5-dimethyl-3(2H)-furanone). The above compounds identified were derived from lipid oxidation, amino acid degradation, and Maillard/Strecker and associated reactions. Both methods revealed the same nature of the aroma components of American country ham. [source] Effect of Gamma-irradiation on Color, Pungency, and Volatiles of Korean Red Pepper PowderJOURNAL OF FOOD SCIENCE, Issue 8 2004J.H. Lee ABSTRACT: Effect of gamma-irradiation on color, pungency, and volatiles of Korean red pepper powder (Capsicum annuum L.) was investigated. Red pepper powder, vacuum-packaged in a polyethylene/polypropylene bag, was gamma-irradiated up to 7 kGy. An irradiation dose of 7 kGy reduced the population of mesophilic bacteria and fungi effectively without affecting major quality factors. Pungency of irradiated red pepper powder was not changed based on the amount of capsanoids by high-performance liquid chromatography (HPLC) and the Scoville sensory score. The red color of irradiated pepper powder was not significantly different from that of the control, judged from the capsanthin content by HPLC and color assessment using spectrophotpmetric (American Spice Trade Assn. units) and colorimetric measurements (Hunter a values). Further, the sensory evaluation showed no significant difference in pungent odor and off-odor between nonirradiated control and irradiated red pepper powder. However, when headspace volatiles of gamma-irradiated red pepper powder were evaluated by gas chromatography/ mass spectrometry with solid-phase microextraction and electronic nose with metal oxide sensors, the profiles of odor were classified into irradiated dose levels of 0, 3, 5, and 7 kGy by principal component analysis and multivariate analysis of variance. Such a difference of odor might result from the disappearance of some volatiles, such as hexanoic acid and tetramethyl-pyrazine, and the appearance of 1,3-di-tert-butylbenzene during irradiation. Moreover, it appears that the irradiation of packaging material induced a formation of 1,3-di-tertbutylbenzene, which migrated into the red pepper powder. [source] Chemical Synthesis of Triple-Labelled Three-Helix Bundle Binding Proteins for Specific Fluorescent Detection of Unlabelled ProteinCHEMBIOCHEM, Issue 6 2005Torun Engfeldt Abstract Site-specifically triple-labelled three-helix bundle affinity proteins (affibody molecules) have been produced by total chemical synthesis. The 58 aa affinity proteins were assembled on an automated peptide synthesizer, followed by manual on-resin incorporation of three different reporter groups. An orthogonal protection strategy was developed for the site-specific introduction of 5-(2-aminethylamino)-1-naphthalenesulfonic acid (EDANS) and 6-(7-nitrobenzofurazan-4-ylamino)-hexanoic acid (NBDX), constituting a donor/acceptor pair for fluorescence resonance energy transfer (FRET), and a biotin moiety, used for surface immobilization. Circular dichroism and biosensor studies of the synthetic proteins and their recombinant counterparts revealed that the synthetic proteins were folded and retained their binding specificities. The biotin-conjugated protein could be immobilized onto a streptavidin surface without loss of activity. The synthetic, doubly fluorescent-labelled affinity proteins were shown to function as fluorescent biosensors in an assay for the specific detection of unlabelled human IgG and IgA. [source] | ||||||||||