Similarities in the aroma chemistry of Gewürztraminer variety wines and lychee (Litchi chinesis sonn.) fruit

GC/O analysis of canned lychees indicated that cis-rose oxide, linalool, ethyl isohexanoate, geraniol, furaneol, vanillin, (E)-2-nonenal, beta-damascenone, isovaleric acid, and (E)-furan linalool oxide were the most odor potent compounds detected in the fruit extracts. However, on the basis of calculated odor activity values (OAVs), cis-rose oxide, beta-damascenone, linalool, furaneol, ethyl isobutyrate, (E)-2-nonenal, ethyl isohexanoate, geraniol, and delta-decalactone were determined to be the main contributors of canned lychee aroma. When these results were compared with GC/O results of fresh lychees and Gewürztraminer wine, 12 common odor-active volatile compounds were found in all three products. These included cis-rose oxide, ethyl hexanoate/ethyl isohexanoate, beta-damascenone, linalool, ethyl isobutyrate, geraniol, ethyl 2-methylbutyrate, 2-phenylethanol, furaneol, vanillin, citronellol, and phenethyl acetate. On the basis of OAVs, cis-rose oxide had the highest values among the common odorants in the three products, indicating its importance to the aroma of both lychee fruit and Gewürztraminer wines. Other compounds that had significant OAVs included beta-damascenone, linalool, furaneol, ethyl hexanoate, and geraniol. This indicated that while differences exist in the aroma profile of lychee and Gewürztraminer, the common odorants detected in both fruit and wine, particularly cis-rose oxide, were responsible for the lychee aroma in Gewürztraminer wine. When headspace SPME was used as a rapid analytical tool to detect the levels of selected aroma compounds deemed important to lychee aroma in Gewürztraminer-type wines, cis-rose oxide, linalool, and geraniol were found to be at relatively higher levels in Gewürztraminers. No cis-rose oxide was detected in the control wines (Chardonnay and Riesling), while lower levels were detected in the Gewürztraminer-hybrid wine Traminette. Gewürztraminers produced in the Alsace region showed differences in the levels of the 3 monoterpenes when compared to those from New York State, which could be attributed to differences in viticultural and enological practices between regions.     

Characterization of odor-active compounds in guava wine

The volatile compounds of guava wine were isolated by continuous solvent extraction and analyzed by GC-FID and GC-MS. A total of 124 volatile constituents were detected, and 102 of them were positively identified. The composition of guava wine included 52 esters, 24 alcohols, 11 ketones, 7 acids, 6 aldehydes, 6 terpenes, 4 phenols and derivatives, 4 lactones, 4 sulfur-compounds, and 5 miscellaneous compounds. The aroma-active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis and by odor activity values. Twelve odorants were considered as odor-active volatiles: (E)-β-damascenone, ethyl octanoate, ethyl 3-phenylpropanoate, ethyl hexanoate, 3-methylbutyl acetate, 2-methyltetrahydrothiophen-3-one, 2,5-dimethyl-4-methoxy-3(2H)-furanone, ethyl (E)-cinnamate, ethyl butanoate, (E)-cinnamyl acetate, 3-phenylpropyl acetate, and ethyl 2-methylpropanoate.     

Evaluation of key odorants in sauvignon blanc wines using three different methodologies

In this study three different approaches were employed to identify key odorants in Sauvignon blanc wines. First, the concentrations of the odorants were compared to their respective aroma detection thresholds. The resulting odor activity values (OAV) were transformed into a normalized and weighted measure that allows the aroma profiles of different wines to be compared and the contribution of a single aroma in a complex mixture to be evaluated. Based on their OAV, 3-mercaptohexanol and 3-mercaptohexyl acetate were the two most important aroma compounds in many Marlborough Sauvignon blanc wines. Due to limitations with the OAV approach, the study was extended to include aroma extract dilution analysis (AEDA), which revealed that β-damascenone, together with the varietal thiols, esters, and higher alcohols, are key odorants in Sauvignon blanc wines. The final approach undertaken was aroma reconstitution and omission tests using a deodorized wine base and the creation of a model Marlborough Sauvignon blanc. Single compounds and groups of compounds were omitted from the model to study their impact on the sensory properties of the model wine. Reconstitution and omission confirmed that varietal thiols, esters, terpenes, and β-damascenone are all important contributors to Sauvignon blanc aroma. The methoxypyrazines showed an important but relatively low impact in all three of the approaches undertaken in this study.     

Aroma extraction dilution analysis of Sauternes wines. Key role of polyfunctional thiols

The aim of the present work was to investigate Sauternes wine aromas. In all wine extracts, polyfunctional thiols were revealed to have a huge impact. A very strong bacon-petroleum odor emerged at RI = 845 from a CP-Sil5-CB column. Two thiols proved to participate in this perception: 3-methyl-3-sulfanylbutanal and 2-methylfuran-3-thiol. A strong synergetic effect was evidenced between the two compounds. The former, never mentioned before in wines, and not found in the musts of this study, is most probably synthesized during fermentation. 3-Methylbut-2-ene-1-thiol, 3-sulfanylpropyl acetate, 3-sulfanylhexan-1-ol, and 3-sulfanylheptanal also contribute to the global aromas of Sauternes wines. Among other key odorants, the presence of a varietal aroma (alpha-terpineol), sotolon, fermentation alcohols (3-methylbutan-1-ol and 2-phenylethanol) and esters (ethyl butyrate, ethyl hexanoate, and ethyl isovalerate), carbonyls (trans-non-2-enal and beta-damascenone), and wood flavors (guaiacol, vanillin, eugenol, beta-methyl-gamma-octalactone, and Furaneol) is worth stressing.     

Stereoselective formation of the varietal aroma compound rose oxide during alcoholic fermentation

The potent aroma compound rose oxide was quantified in several white wines by a headspace solid-phase microextration stable isotope dilution assay (HS-SPME-SIDA) and the enantiomeric ratios of the cis diastereomers were determined by enantioselective capillary GC. The most odor-active stereoisomer (23)-cis-rose oxide was detectable in all investigated white wines ranging from 0.2 to 12 microg/L. However, its contribution to the overall aroma in some white wine varieties can be neglected as indicated by a low odor activity value (OAV). The highest concentrations were found in Gewürztraminer wines, confirming the importance of rose oxide as a varietal aroma compound in this variety. Surprisingly, the enantiomeric ratio of cis-rose oxide in all investigated wines was substantially lower than in nonfermented musts and in some wines almost racemic cis-rose oxide was detected. Fermentation studies with a model must that contained deuterated water revealed that yeast is capable of reducing the precursor 3,7-dimethyl octa-2,5-dien-1,7-diol (geranyl diol I) yielding 3,7-dimethyl-5-octen-1,7-diol (citronellyl diol I) that gives rise to cis- and trans-rose oxide after acid catalyzed cylization. The deuterium labeling pattern of the resulting rose oxide stereoisomers and a clearly detectable kinetic isotope effect indicate that at least two different reductive pathways in yeast exist that yield cis-rose oxide with different enantiomeric ratios altering the genuine enantiomeric ratio in grape musts. The presence of (+)-cis-rose oxides in wines can therefore be attributed to the reductive yeast metabolism during fermentation. This observation corroborates recent findings that the modification of terpene derived varietal aroma is an integral part of yeast metabolism and not only a simple hydrolytical process.     

Odor-active compounds of Iberian hams with different aroma characteristics

The odor-active compounds of different commercial types of Iberian hams (Montanera and Pienso) were researched by gas chromatography-olfactometry based on a detection frequency method. The hams (long- and short-Montanera and Pienso Iberian hams) showed different sensory profiles, differences being significant for Montanera ham typical odor, aroma intensity and persistence, and cured and moldy aroma. Significant differences were also found for some odorants. The largest differences appeared in 2-acetyl-1-pyrroline, hexanal, (Z)-3-hexenal, ethyl 2-methylbutyrate, (E)-2-hexenal, 1-octen-3-one, 1-octen-3-ol, 2-propionyl-1-pyrroline, octanal, and an unknown odorant. Sensory characteristics and olfactometric profiles were significantly different between Montanera and Pienso hams. Significant differences also appeared between long- and short-Montanera hams, which shows great variability in this commercial type. Otherwise, the largest scores for moldy aroma in long-Montanera hams matched with the largest detection frequency of 1-octen-3-one and 1-octen-3-ol in this group.     

不同酶和酵母对干红葡萄酒香气影响的差异分析

为提高甘肃河西产区蛇龙珠干红葡萄酒的香气品质,优化酿酒工艺,该文采用顶空固相微萃取和气相色谱-质谱联用技术,分析比较了添加不同浸渍酶和酵母发酵的蛇龙珠干红葡萄酒的香气构成。结果显示:蛇龙珠干红葡萄酒中初步定性香气化合物75种,主要为酯、醇、酸、萜烯和酚类物质。比较酯类、萜烯类等香气成分质量浓度和香气物质释放总量,EX-V酒样明显高于EX和HC酒样,D254酒样明显高于BDX酒样。各组酒样主要香气成分构成相似,但微量香气成分差异显著。果香是香气强度最高的香气系列,植物香、脂肪香、花香次之,其香气强度EX-V酒样高于EX和HC酒样,D254酒样高于BDX酒样。浸渍酶和酵母对甘肃河西产区蛇龙珠干红葡萄酒香气品质的影响评价显示,浸渍酶EX-V优于EX和HC,酵母D254优于BDX。研究结果可为甘肃河西产区蛇龙珠干红葡萄酒香气品质的提高及酿造工艺研究提供科学数据参考。     

Odorous impact of volatile thiols on the aroma of young botrytized sweet wines: identification and quantification of new sulfanyl alcohols

Specific extraction of volatile thiols using sodium p-hydroxymercuribenzoate revealed the presence of three new sulfanylalcohols in wines made from Botrytis-infected grapes: 3-sulfanylpentan-1-ol (II), 3-sulfanylheptan-1-ol (III), and 2-methyl-3-sulfanylbutan-1-ol (IV). The first two have citrus aromas, whereas the third is reminiscent of raw onion. In addition, 2-methyl-3-sulfanylpentan-1-ol, which has a raw onion odor, was tentatively identified. Like 3-sulfanylhexan-1-ol (I), already reported in Sauternes wines, compounds II, III, and IV were absent from must. They were found in wine after alcoholic fermentation, and their concentrations were drastically higher when Botrytis cinerea had developed on the grapes. In the commercial botrytized wines analyzed, the mean levels of II, III, and IV were 209, 51, and 103 ng/L, respectively. Despite their low odor activity values, sensory tests showed additive effects among I, II, and III, thus confirming their olfactory impact on the overall aroma of botrytized wines.     

Characterization of aroma-active compounds in raw and cooked pine-mushrooms (Tricholoma matsutake Sing.)

The characteristic aroma-active compounds in raw and cooked pine-mushrooms (Tricholoma matsutake Sing.) were investigated by gas chromatography-olfactometry using aroma extract dilution analysis. 1-Octen-3-one (mushroom-like) was the major aroma-active compound in raw pine-mushrooms; this compound had the highest flavor dilution factor, followed by ethyl 2-methylbutyrate (floral and sweet), linalool (citrus-like), methional (boiled potato-like), 3-octanol (mushroom-like and buttery), 1-octen-3-ol (mushroom-like), (E)-2-octen-1-ol (mushroom-like), and 3-octanone (mushroom-like and buttery). By contrast, methional, 2-acetylthiazole (roasted), an unknown compound (chocolate-like), 3-hydroxy-2-butanone (buttery), and phenylacetaldehyde (floral and sweet), which could be formed by diverse thermal reactions during the cooking process, together with C8 compounds, were identified as the major aroma-active compounds in cooked pine-mushrooms.     

Chemical characterization of commercial Sherry vinegar aroma by headspace solid-phase microextraction and gas chromatography-olfactometry

The sensorial representativeness of the headspace solid-phase microextraction (HS-SPME) aroma extract from commercial Sherry vinegars has been determined by direct gas chromatography-olfactometry (D-GCO). Extracts obtained under optimal conditions were used to characterize the aroma of these vinegars by means of GCO and aroma extract dilution analysis (AEDA). Among the 37 different odorants determined, 13 of them were identified for the first time in Sherry vinegars: 2 pyrazines (3-isopropyl-2-methoxypyrazine, 3-isobutyl-2-methoxypyrazine), 2 sulfur compounds (methanethiol, dimethyl trisulfide), 1 unsaturated ketone (1-octen-3-one), 1 norisoprenoid (β-damascenone), 1 ester (ethyl trans-cinnamate) and 6 aldehydes (2- and 3-methylbutanal, octanal, nonanal, (E)-2-nonenal and (E,E)-2,4-decadienal). The determination of the odor thresholds in a hydroacetic solution together with the quantitative analysis-which was also performed using the simple and fast SPME technique-allowed obtaining the odor activity values (OAV) of the aromatic compounds found. Thus, a first pattern of their sensory importance on commercial Sherry vinegar aroma was provided.     

Sensory threshold of 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and concentrations in young Riesling and non-Riesling wines

1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) is well-known to contribute "petrol" aromas to aged Riesling wines, but its prevalence and contribution to young Riesling or non-Riesling wines is not well understood. TDN concentrations were measured in 1-3-year-old varietal wines produced from Cabernet franc (n = 14 wines), Chardonnay (17), Cabernet Sauvignon (4), Gewurztraminer (4), Merlot (9), Pinot gris (6), Pinot noir (9), Riesling (28), or Sauvignon blanc (6). TDN concentrations in the Riesling wines, 6.4 ± 3.8 μg/L, were significantly higher than in all other varietals, 1.3 ± 0.8 μg/L. The odor detection thresholds for TDN were then determined in both model wine and a neutral white wine. Group sensory thresholds were found to be the same in both matrices, 2 μg/L, indicating little masking of TDN due to the odorants in the neutral white. The TDN sensory threshold was a factor of 10 below the previously reported odor threshold. On the basis of this revised threshold, 27 of 28 Riesling wines had suprathreshold TDN, whereas only 7 of 69 non-Riesling wines had suprathreshold TDN. The monoterpenes linalool and geraniol were also measured in the Riesling wines, and odor activity values (OAVs) were calculated for the monoterpenes and TDN. The OAV for TDN was higher than for the monoterpenes in 25 of 28 Riesling wines.     

Impact odorants of different young white wines from the Canary Islands

Five young monovarietal white wines from the Canary Islands made from Gual, Verdello, Marmajuelo, white Listán, and Malvasia grape cultivars were studied to determine the characteristics of their most important aromas and the differences among them. The study was carried out using gas chromatography-olfactometry (GC-O) to detect the potentially most important aroma compounds, which were then analyzed quantitatively by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. The strongest odorants in the GC-O experiments were similar in all cases, although significant differences in intensity between samples were noted. Calculation of the odor activity values (OAVs) showed that 3-mercaptohexyl acetate was the most active odorant in the Marmajuelo and Verdello wines, as were 3-methylbutyl acetate in the Gual wine, beta-damascenone in the Malvasia wine, and ethyl octanoate in the white Listán wine. However, the most important differences between varieties were caused by the three mercaptans (3-mercaptohexyl acetate, 3-mercaptohexanol, and 4-methyl-4-mercapto-2-pentanone) and the vinylphenols (4-vinylphenol and 2-methoxy-4-vinylphenol). The correlation between the olfactometric values and the OAVs was satisfactory in the cases when the compound eluted in the GC-O system was well isolated from other odorants and had aromatic importance and the OAVs for the different wines were sufficiently different.     

Characterization of the key aroma compounds in an american bourbon whisky by quantitative measurements, aroma recombination, and omission studies

Thirty-one of the 45 odor-active compounds previously identified by us in an American Bourbon whisky were quantified by stable isotope dilution assays. Also for this purpose, new synthetic pathways were developed for the synthesis of the deuterium-labeled whisky lactone as well as for gamma-nona- and gamma-decalactone. To obtain the odor activity values (OAVs), the concentrations measured were divided by the odor thresholds of the odorants determined in water/ethanol (6:4 by vol.). Twenty-six aroma compounds showed OAVs >1, among which ethanol, ethyl (S)-2-methylbutanoate, 3-methylbutanal, 4-hydroxy-3-methoxybenzaldehyde, (E)-beta-damascenone, ethyl hexanoate, ethyl butanoate, ethyl octanoate, 2-methylpropanal, (3S,4S)- cis-whiskylactone, (E, E)-2,4-decadienal, 4-allyl-2-methoxyphenol, ethyl-3-methylbutanoate, and ethyl 2-methylpropanoate showed the highest values. The overall aroma of the Bourbon whisky could be mimicked by an aroma recombinate consisting of the 26 key odorants in their actual concentrations in whisky using water/ethanol (6:4 by vol.) as the matrix. Omission experiments corroborated the importance of, in particular, 4-hydroxy-3-methoxybenzaldehyde, (3S,4S)-cis-whiskylactone, ethanol, and the entire group of esters for the overall aroma of the Bourbon whisky.     

Differences in odor-active compounds of trincadeira wines obtained from five different clones

Odorant compounds of five young clonal red wines made from cv. Trincadeira, a native grape variety of Vitis vinifera L. grown in Portugal, were studied using 2001 and 2003 vintages. The study was carried out using gas chromatography-mass spectrometry (GC-MS) for compound identification and the gas chromatography-olfactometry (GC-O) posterior intensity method to detect the potentially most important aroma compounds. Forty-one odorant peaks were detected by GC-O analysis, from which 31 were identified by GC-MS. The odorant compounds with the highest odorant average intensities are 3-methylbutanoic acid, 2-phenylethanol, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and 4-vinylguaiacol. The GC-O analysis showed odor intensity differences among compounds, which was confirmed by analysis of variance (ANOVA). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed that the five clonal wines from the 2001 vintage were more similar than those from the 2003 vintage. Moreover, stepwise linear discriminant analysis (SLDA) demonstrated that the factor vintage has influence on the Trincadeira clonal red wine odorant profile differentiation.     

Composition of the essential oil of Mentha microphylla from the Gennargentu Mountains (Sardinia,Italy)

The essential oil obtained by hydrodistillation of the fresh aerial parts of Mentha microphylla C. Kock (Lamiaceae) collected on the Gennargentu Mountains (Sardinia, Italy) has been investigated by gas chromatography (GC) and GC/mass spectrometry (MS). The main constituents that resulted were pulegone (34.1%), piperitenone oxide (32.9%), and piperitenone (11.3%). The presence of small amounts of compounds such as ethyl hexanoate, 1-octen-3-ol, nonanal, and ethyl 2-methylbutanoate could justify the particular odorous profile of the plant, resembling the aroma of milk and other dairy products such as mozzarella.     

Investigation of potent odorants and afterodor development in two Chardonnay wines using the buccal odor screening system (BOSS)

Potent odorants of two Chardonnay wines were characterized according to their specific overall aroma profiles and their intraoral release patterns after wine consumption. Therefore, aroma compounds were isolated and analyzed by means of high resolution gas chromatography-olfactometry (HRGC/O), leading to the detection of 36 odor-active compounds in both wines. All compounds were identified. Of the most potent odorants, 25 were quantified in both wines by means of stable isotope dilution assays. For the intraoral investigation of odor compounds at defined times after Chardonnay wine consumption, the recently developed buccal odor screening system was used. Significant differences in the oral persistence of characteristic odor notes were observed for both wines with mainly the characteristic barrique-notes being highly persistent, while fruity notes quickly disappeared from the oral cavity. The obtained analytical data were related to time-resolved retronasal aroma evaluation.