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Gas Chromatographic, Infrared Proton Magnetic Resonance, Mass Spectral, and Threshold Analyses of All Pentyl Acetates
Abstract
The eight pentyl acetate isomers and cyclopentyl acetate, obtained from commercial sources or by synthesis, were purified by preparative gas chromatography, and purity of each sample was determined by high resolution analytical gas chromatography. The infrared, proton magnetic resonance, and mass spectra of each of the nine compounds were recorded, and samples of each were subjected to organoleptic evaluation for threshold and discrimination determinations.
... *Unpublished E & J Gallo data. a (Guth, 1997); b (Teranishi et al., 1966); c (Etievant, 1991); d (Ferreira, López, & Cacho, 2000); e (Boutou & Chatonnet, 2007); f (Peinado, Moreno, Bueno, Moreno, & Mauricio, 2004); g (Liu & Pilone, 2000). Detection thresholds were reported in aqueous ethanol, model wine or (red and white) wine matrices. ...
The ability to create differentiated red wine styles is key to meeting the diverse preferences of wine consumers. This study investigated the composition and style of Merlot wines made from flash détente (FD) treated must fermented with different levels of grape solids and skin contact time, and the potential for pre-fermentation addition of enotannin (0.4 g/L) or oak chips (4 g/L) to stabilize color. Off-skins fermentations, with or without addition of enotannin, gave wines with enhanced red fruit and confectionery characters (P=0.0001), whereas addition of oak chips gave wines with prominent dark fruit, vanilla, toasty and allspice characters (P=0.0001). However, additives did not improve wine color stability. Macerative fermentation of FD must enhanced dark fruit, body and astringency ratings (P=0.0001), with FD wines exhibiting less intense green, savory and dusty notes (P=0.0001). The study demonstrated solids removal had a greater influence on wine composition and style than skin contact time.
... Although sensory thresholds provide a rough estimation of the real contribution of each volatile compound to the global aroma, they are generally used to evaluate the potential sensory contribution of a given compound. Of the yeast volatile fermentation products measured in all wines, 17 compounds exhibited concentrations over their reported sensory thresholds (Teranishi et al. 1966, Salo 1970, Shinohara and Watanabe 1976, Simpson 1979, Étievant 1991, Guth 1997, Ferreira et al. 2000 in the inoculated fermentation wines. In contrast, 20 compounds showed concentrations higher than their sensory thresholds in wines from uninoculated fermentations. ...
Background and Aims: Winemakers are constantly searching for new techniques to modulate wine style. Exploiting indigenous yeasts present in grape must is re-emerging as a commercial option in New World wine regions. Wines made with indigenous or ‘wild’ yeasts are perceived to be more complex by showing a greater diversity of flavours; however, the chemical basis for the flavour characteristics is not yet defined. In order to evaluate techniques for making wine with the ‘wild yeast fermentation’ character more reliably, it is necessary to define the salient chemical characteristics of such wines.Methods and Results: Pairs of Chardonnay wines were prepared from the same must and subjected to similar fermentation conditions in the wineries of origin, except for the mode of inoculation. Reference wines were made by inoculation with a Saccharomyces cerevisiae starter culture, whereas companion wines were allowed to undergo fermentation with the indigenous microflora. Of all wine chemicals analysed, only yeast-derived volatile fermentation products showed significant differences between the yeast treatments.Conclusions: Inoculated wines were associated with the esters ethyl hexanoate and 3-methylbutyl acetate and formed a clear cluster by principal component analysis. By comparison with inoculated wines, ‘wild’ yeast fermented wines showed high variability in volatile compounds that contribute to wine aroma, with higher concentrations of 2-methylpropanol, 2-methylbutanoic acid, ethyl 2-methylpropanoate, ethyl decanoate and ethyl dodecanoate potentially being sensorially important.Significance of the Study: This study shows that yeast-derived volatile fermentation products are a key difference between inoculated and uninoculated ferments and provides a chemical basis for the ‘wild yeast fermentation’ character.
Separation process is one of the key processes in the production of fruit spirits, including the traditional distillation method and the new pervaporation membrane method. The separation process significantly determines the constituents and proportions of compounds in the fruit spirit, which has a significant impact on the spirit quality and consumer acceptance. Therefore, it is important and complex to reveal the changing rules of chemical substances and the principles behind them during the separation process of fruit spirits. This review summarized the traditional separation methods commonly used in fruit spirits, covering the types, principles, and corresponding equipment of distillation methods, focused on the enrichment or removal of aroma compounds and harmful factors in fruit spirits by distillation methods, and tried to explain the mechanism behind it. It also proposed a new separation technology for the production of fruit spirits, pervaporation membrane technology, summarized its working principle, operation, working parameters, and application in the production of fruit spirits, and outlined the impact of the separation method on the production of fruit spirits based on existing research, focusing on the separation of flavor compounds, sensory qualities, and hazard factors in fruit spirits, along with a preliminary comparison with distillation. Finally, according to the current researches of the separation methods and the development requirement of the separation process of fruit spirits, the prospect of corresponding research is put forward, in order to propose new ideas and development directions for the research in this field.
This study investigated the color, phenolic, polysaccharide, volatile and sensory profiles of Cabernet Sauvignon wines made from flash détente (FD) treated musts fermented at different temperatures (16, 24 or 32 °C), with and without suspended grape solids. Low fermentation temperature and low solids content increased the concentration of esters, whereas the opposite conditions increased the concentration of fusel alcohols, polysaccharides and glycerol. Higher fermentation temperatures also increased linalool concentration independent of solids content. Traditional maceration fermentation conditions gave the highest concentration of fusel alcohols and 1-hexanol relative to FD treatments. Pre-fermentation removal of grape solids from FD juice created wines with increased red fruit and confectionery attributes, whereas inclusion of 3.5% grape solids increased dark fruit notes. In comparison, control wines had significantly higher green and savory attributes compared to wines from FD treatments. Research findings demonstrated the potential for FD to be used to create differentiated red wine styles.
Reductive acetylation of a variety of carbonyl compounds such as aldehydes, ketones and a,b-unsaturated enals/enones was carried out efficiently with pyridine zinc borohydride, (Py)Zn(BH4)2, in a mixture of THF-EtOAc at room temperature or under reflux condition. The corresponding acetates were obtained in high to excellent yields. In addition, chemoselective reductive acetylation of aldehydes over ketones was achieved perfectly with the reagent at room temperature.
Reductive acetylation of a variety of carbonyl compounds such as aldehydes, ketones and a,b-unsaturated enals/enones was carried out efficiently with pyridine zinc borohydride, (Py)Zn(BH4)2, in a mixture of THF-EtOAc at room temperature or under reflux condition. The corresponding acetates were obtained in high to excellent yields. In addition, chemoselective reductive acetylation of aldehydes over ketones was achieved perfectly with the reagent at room temperature.
A series of straight chain and branched esters (ethyl acetate to 2-nonyl acetate) were purified by preparative gas chromatography and their odour thresholds were determined using sensory panel methods. Pentyl acetate and 2-butyl acetate had the lowest odour thresholds of the straight chain and branched acetates, respectively. Addition of a methyl group at the 1-position of the alcohol did not have a consistent effect on the odour threshold. For ethyl acetate, propyl acetate, butyl acetate and heptyl acetate the addition of a methyl group in the 1-position caused a decrease in the odour threshold; whereas for pentyl acetate, hexyl acetate and octyl acetate the addition of a methyl group in the 1-position caused an increase in the odour threshold.
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The analysis of minor volatile constituents in alcoholic beverages presents difficulties because of the relatively high concentrations of a few higher alcohols. Volatile components were extracted from a freshly prepared Riesling white table wine using the solvent trichlorofluoromethane, and analysed by combined gas chromatography-mass spectrometry. The higher alcohols were then removed from the trichlorofluoromethane extracts by treatment with propylene glycol, and the remaining components, mainly esters, were concentrated further. The final concentrate, whose volume represented about 0·01% of that of the wine, was analysed again, and in all, over 40 components were identified. Some of the esters observed, including the mixed ester, 3-methylbutyl ethyl succinate, have not been reported previously.
Various biochemical transformations involved in vinous fermentations are reviewed from the point of view of their formal ion of volatile aroma or flavor compounds in fermented beverages. In addition to the recently elucidated processes for the formation of aliphatic primary alcohols of molecular weight greater than that of ethanol, Nordström's mechanism for the formation of esters during fermentation is discussed. Experimental evidence supporting this mechanism in vinous fermentation is presented; the White Riesling grape is found to contain insignificant, quantities of esters while the wine prepared from these grapes, analyzed immediately after fermentation, shows relatively large amounts of several volatile esters. In addition, in an investigation of an older California sherry, ethyl acid malate is found to be nearly all the single isomer with the hydroxyl group on the carbon adjacent, to the free carboxyl group. This finding suggests an enzymatic (presumably vinous fermentative) production rather than simple chemical esterification in the wine after fermentation. An extension of Nordström's mechanism for ester production is proposed to explain the formation of certain secondary amides found in wines.
Cell Proliferation and Migration in Olfactory Epithelium of the MouseOlfactory Sensitivity in MammalsSummaryDiscussionReferences
Durch Flssig-Flssig-Extraktion aus Weinen der SortenRiesling, Rulnder, Traminer undScheurebe gewonnene Aromaextrakte wurden sulenchromatographisch an Kieselgel fraktioniert. In den von polaren Verbindungen abgetrennten Pentan-Elutionen wurden gaschromatographisch-massenspektrometrisch ber Dnnschicht-Capillarsulen 72 Aromastoffe getrennt und identifiziert. Die zahlen- und mengenmig dominierenden Ester bedingen das typische Esteraroma dieser Fraktion. Anhand spezieller Beispiele wird der Einflu der Traubensorte und der Reife diskutiert. Die massenspektrometrischen Daten von 28 erstmals im Wein nachgewiesenen Aromakomponenten sind angegeben.Aroma extracts obtained by liquid-liquid extraction of wines of the varietiesRiesling, Rulnder, Traminer andScheurebe had been fractioned, employing column-chromatography and using silicagel as adsorbent. 72 aroma constituents in the pentane-elutions, separated from its polar compounds, had been separated and identified by means of the combination gaschromatography-mass-spectrometry employing thin-layer capillary columns. The esters are domineering, numerically and quantitatively, and cause the typical ester aroma of this fraction. With the help of especially selected examples the influence of the variety and of the ripeness of the grapes is discussed. Mass-spectrometrical data are reported of 28 aroma components which had been identified for the first time in wine.
Extracts obtained from Elstar and Cox-Orange apples (Malus var. domestica Borkh.) were screened for potent odorants by aroma extract dilution analysis (AEDA). (E)-beta-Damascenone (I), (E)-beta-damascone (II), hexanal (III), (Z)-3-hexenal (IV), (Z)-2-nonenal (V), linalool (VI), butyl acetate (VII), 2-methylbutyl acetate (VIII) and hexyl acetate (IX) were identified in Elstar and I, III-V, ethyl butanoate (X), ethyl 2-methylbutanoate (XI), 1-octen-3-one (XII), (E)-2-octenal (XIII), methional (XIV), (E)-2-nonenal (XV), eugenol (XVI) and wine lactone (XVII) in Cox Orange. The release of odorants by the cultivars was analysed by gas chromatography-olfactometry of headspace samples. Esters X and XI showed the highest odour activities in the air above Elstar apples and ester X, acetaldehyde (XVIII), 2-methylbutanol (XIX) and ethyl methylpropanoate (XX) in that of Cox Orange. Preparation of a homogenate changed the headspace composition of potent odorants. Hexyl acetate (IX) became the key odorant of Elstar and aldehydes III and IV those of Cox Orange. Quantification and calculation of odour activity values indicated I, IV, V, VII, VIII and IX as the character impact odorants of the fruit flesh of the two cultivars. Elstar contained more I, V, VII and IX and Cox Orange more IV than the other cultivar. The concentrations of VIII were similar.
The yeast Saccharomyces cerevisiae synthesises a variety of volatile aroma compounds during wine fermentation. In this study, the influence of fermentation temperature on (1) the production of yeast-derived aroma compounds and (2) the expression of genes involved in aroma compounds' metabolism (ADH1, PDC1, BAT1, BAT2, LEU2, ILV2, ATF1, ATF2, EHT1 and IAH1) was assessed, during the fermentation of a defined must at 15 and 28 degrees C. Higher concentrations of compounds related to fresh and fruity aromas were found at 15 degrees C, while higher concentrations of flowery related aroma compounds were found at 28 degrees C. The formation rates of volatile aroma compounds varied according to growth stage. In addition, linear correlations between the increases in concentration of higher alcohol and their corresponding acetates were obtained. Genes presented different expression profiles at both temperatures, except ILV2, and those involved in common pathways were co-expressed (ADH1, PDC1 and BAT2; and ATF1, EHT1 and IAH1). These results demonstrate that the fermentation temperature plays an important role in the wine final aroma profile, and is therefore an important control parameter to fine-tune wine quality during winemaking.
A simple technique for measurement of olfactory thresholds of odorous materials is described. Sensitivity and reproducibility of the method was good, but many precautions must be taken to insure reliability of results. Olfactory thresholds for a number of pure compounds, several of which were identified in potatoes, are presented. In general, sulphur compounds and short-chain unsaturated aldehydes gave the lowest and highest thresholds, respectively. The thresholds of a homologous series of saturated aliphatic aldehydes decreased progressively with increase in chain length from C5 to C10. Similar results were obtained with a series of unsaturated aldehydes. Thresholds of some of the more potent compounds were less than 0.1 of a part per 109 parts of water.
The high resolution mass spectra of 27 aliphatic esters have been obtained. It is possible to assign a formula for each fragment ion in the spectra, which makes it easier to identify a compound from its spectrum and, in particular, to distinguish an ester from compounds such as isobaric alcohols, ethers, and acids.
Large-bore capillary columns, 0.02-inch i.d. and 0.03-inch i.d., 500 feet and 1000 feet long, respectively, have been made with theoretical plate values equal to or better than those obtained with 0.01-inch i.d. columns 100 to 200 feet long. The capacity of the large-bore columns permits direct injection, nondestructive thermistor detectors permit the isolation of tenths of milligram quantities of pure material per run. Construction and performance of a low-pressure-drop packed column are discussed.
Important fragmentation peaks in the mass spectra of 31 aliphatic esters have been correlated with molecular structures. Each type of ester produced a characteristic major rearrangement peak. A possible process for the formation of these rearrangement ions is discussed. Examples are given of the use of both rearrangement and fragmentation peaks for the identification of esters.