24 research outputs found
Analysis of Volatile Components of Varietal English Wines Using Stir Bar Sorptive Extraction/Gas Chromatography-Mass Spectrometry
No full textAroma is an important property of wine and it can be influenced significantly by enological practices. The aim of this work was, by use of stir bar sorptive extraction/gas chromatography-mass spectrometry (SBSE/GC-MS), to compare semi-quantitative concentrations of the volatile constituents of stainless steel tank-fermented/matured Huxelrebe, Ortega, Schönburger and Siegerrebe varietal wines from a commercial English vineyard, with corresponding wines produced by oak cask (‘barrel’) fermentation/maturation. Aroma profiles of tank and barrel wines were different, with more volatiles detected and net concentrations being higher in barrel wines. Long chain ethyl carboxylate esters were generally more abundant in barrel wines, whereas acetate esters were generally more prominent in tank wines. By conducting a short (~7 month) maturation period in secondhand (third or fourth fill) casks, it was possible to make wines with more complex aromas, but without obvious oak aroma
Determination of volatile organic compounds in English vineyard grape juices by immersion stir bar sorptive extraction–gas chromatography/mass spectrometry
No full textImmersion stir bar sorptive extraction-gas chromatography-mass spectrometry was used to analyse the volatile organic components of English vineyard grape juices. Four juices, Huxelrebe, Ortega, Schonburger and Siegerrebe, of the 2004 season, were from a commercial vineyard. The fifth, Madeleine Angevine 7672, of the 2000 vintage, was from a private vineyard. Madeleine Angevine juice exhibited the greatest number (113) of identified volatile components, followed by Siegerrebe, Huxelrebe, Schonburger and Ortega, with 78, 74, 70 and 69, respectively. Many compounds are common to all five varieties and very few of the more concentrated components are unique to a particular variety, except (E)-anethole, estragole and methyl salicylate, which were unique to Madeleine Angevine, for these particular vintages. Of the compounds that are common to more than two varieties, Madeleine Angevine had the highest levels of (E)-ethyl cinnamate, hexanol, (E)-2-hexenol, hotrienol, limonene and (E)-methyl cinnamate. Siegerrebe had the highest concentrations of beta-citronellol, diendiol-I, geraniol, dihydromethyl jasmonate, linalool (32 000 ng/l), (Z)- and (E)-linalool oxide (both furanoid and pyranoid forms) and a-terpineol. This variety also had high levels of 1-hexanol, (E)-2-hexenal and (E)-2-hexenol. Huxelrebe had the highest concentrations of (E)-2-hexenal and (E)-theaspirane; Schonburger had the highest levels of (Z)-3-hexenol, nerol and nerol oxide; and Ortega had the highest concentrations of beta-damascone and beta-damascenone. Copyright (C) 2007 John Wiley & Sons, Ltd
N-Phenyl-tert-butanesulfinamide
No full textIn the racemic title compound, C10H15NOS, the packing exhibits centrosymmetric pairs of molecules linked by N—H...O=S hydrogen bonds in a head-to-tail fashion. The N—Caryl bond [1.4083 (12) Å] is considerably shorter than the N—Calkyl bonds typically found in N-alkylalkanesulfinamides (1.470–1.530 Å)
Hydrolysis of <i>N-</i>Phenylalkanesulfinamides in Aqueous Mineral Acids
No full textThe acid-catalyzed hydrolysis of N-phenylalkanesulfinamides (RSONHPh; 1, R = (i)Pr; 2, R = (t)Bu; 3, R = 1-adamantyl) has been studied in aqueous mineral acids. Hydrolysis was found to proceed via a slow spontaneous (uncatalyzed) pathway, an A-2 (bimolecular) acid-catalysis pathway, and an acid-dependent nucleophilic catalysis pathway, the last of which predominates in hydrobromic and hydrochloric acid solutions. A mechanistic switch over from A-2 to A-1 was detected for compounds 2 and 3 in concentrated sulfuric acid. Order of catalytic activity, effect of added salts, Arrhenius parameters, kinetic solvent isotope, and solvent effects are all consistent with the proposed mechanisms
Comparison of volatile constituents extracted from model grape juice and model wine by stir bar sorptive extraction–gas chromatography–mass spectrometry
No full textA stir bar sorptive extraction (SBSE) method coupled with gas chromatography-mass spectrometry was optimised for the analysis of volatile components of a model wine, based on a previously optimised method used for analysis of the same components in model grape juice. The presence of ethanol in the model wine sample matrix resulted in decreased sensitivity of the method toward most of the volatile constituents. Mean percent relative recoveries and reproducibilities (%CV) were 22.8% and 7.1%, respectively, compared with 28.4% and 8.5% for model grape juice. The mean limit of detection CLOD) ratio (juice:wine) was 0.25. Similar sensitivities for the two sample matrices using this method were achieved by changing the split ratio from 20:1 (grape juice) to 5:1 (wine), giving a mean limit of detection ratio (juice:wine) of 1.0, thus allowing direct comparison of chromatograms of volatile components in the two matrices. This enabled direct comparisons of grape juices and the wines derived from them by alcoholic yeast fermentation. The influence of ethanol concentration in the range 9-15% on method sensitivity is discussed, using an overlay of the total ion chromatograms. The use of a gas saver device for the 5:1 split ratio analysis of desorbed model wine aroma compounds is discussed in terms of preventing extraneous reaction of sorbent and stationary phases with air during analysis. (C) 2011 Elsevier B.V. All rights reserved
Seasonal variation of flavour content of English vineyard grapes, determined by stir-bar sorptive extraction-gas chromatography-mass spectrometry
No full textThe juices (musts) of Huxelrebe, Madeleine Angevine 7672, Ortega, Schonburger and Siegerrebe wine grapes of up to four vintages from two East Anglian vineyards were analysed for volatile flavour components, using stir-bar sorptive extraction-gas chromatography-mass spectrometry. The analytical flavour profiles for each variety differed considerably from season to season, depending on ripeness (and in turn on seasonal weather and yield), as judged by sugar content. (E)-Anethole and estragole were most abundant in less ripe juices, although in all cases their concentrations were low. Likewise, C6 aldehydes hexanal and (E)-2-hexenal, as well as other carbonyl compounds, were more abundant in less ripe musts. Additionally, the aliphatic: aromatic ester ratio tended to be higher for riper musts, and higher concentrations of decanoic and dodecanoic acids tended to characterize riper juices. Aliphatic alcohols and terpenoids showed mixed trends. Despite the seasonal differences in flavour profiles, it was deduced that very few variations of individual components were likely to have much organoleptic impact in themselves. Seasonal variations in linalool and (E)-beta-damascenone contents probably had the greatest flavour (aromatic fruity) impact on Schonburger and Siegerrebe juices and Huxelrebe and Ortega juices, respectively. Copyright (C) 2008 John Wiley & Sons, Ltd
N-(3-Methoxyphenyl)-tert-butanesulfinamide
No full textIn the title compound, C11H17NO2S, the molecules interact in a head-to-tail fashion through pairs of N&#8212;H...O hydrogen bonds, giving discrete centrosymmetric dimers. The N(H)S(O)tBu fragment is disordered over two sets of positions, with the major component comprising 90.0&#8197;(2)%
Determination of optimum conditions for the analysis of volatile components in pine needles by double-shot pyrolysis-gas chromatography-mass spectrometry
No full textThe optimum conditions for the analysis of the volatile organic components of pine needles from Pinus densiflora using double-shot pyrolysis-gas chromatography-mass spectrometry (DSP-GC-MS) were investigated with respect to thermal desorption temperature and duration of heating. A total of 41 compounds were identified using thermal desorption temperatures of 150 degrees C, 200 degrees C, 250 degrees C and 300 degrees C. Thermal decomposition products, which include acetol, acetic acid, furfurals and phenols, were observed only at thermal desorption temperatures exceeding 250 degrees C: they were not observed in the extract from a simultaneous distillation extraction (SDE) method. Heating times of 1 s, 6 s, 30 s, 150 s and 300 s were investigated at the thermal desorption temperature of 200 degrees C, whence it was found that thermal decomposition products were produced only at heating times over 30 s. The optimum pyrolyzer conditions for the analysis of pine needles using DSP-GC-MS is 200 degrees C for 6 s. Under these conditions, this method gives comparable results to the SDE method. (c) 2005 Elsevier B.V. All rights reserved
Determination of volatile components of pine needles from Pinus densiflora S. using solid phase trapping extraction-gas chromatography-mass spectrometry
No full textVolatile components of the needles from Pinus densiflora were studied by gas chromatography-mass spectrometry (GC-MS) applying a new solid phase trapping extraction (SPTE) method and a Magic Chemisorber (TM) (MC). In SPTE, a titanium tube of the surface covered With polydimethylsiloxane (PDMS) was used. The efficiency of SPTE method was studied by varying extraction temperature (20, 35, 50 and 65 degrees C) at a fixed extraction time of 20 min. The optimum temperature was 35 degrees C. Extraction efficiency of SPTE method was conpared to that of SPME method under the same optimum conditions (extraction time 20 min, extraction temperature 35 degrees C). For SPTE, extraction efficiency of hydrocarbons increased with the increasing temperature. However, alcohols and carbonyls, such as 2-hexenal, 1-hexanol, and cis-3-hexenol were extracted less efficiently at higher temperatures. Fatty acids, such as capric, lauric, myristic, pentadecanoic, and palmitic were identified by SPTE, but not by SPME under the same (SPTE optimum) experimental conditions
