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ABSTRACT: A preparative HPLC method was applied to aromatic red wine extracts. Twenty-five fractions with various flavors were thus obtained, and several aromatic reconstitutions were produced by mixing some of these fractions. Discriminative tests revealed that the omission of some fractions from the mixture of fruity fractions or the addition of others affected the overall expression of fruity aroma. Sensory profile analyses identified significant differences among aromatic reconstitutions in terms of intensity of black-berry, as well as fresh-, and jammy-fruit descriptors. A fraction with a very low fruity note (fraction 17) had an additive effect on the fresh fruity aroma, while fractions with caramel and lactic notes (fractions 3-5) had a masking effect on this aroma and an additive effect on the jammy-fruit aroma. Further analysis revealed that ethyl 2-hydroxy-4-methylpentanoate was eluted in fraction 17, while diacetyl, acetoin, acetic acid, and γ-butyrolactone were eluted in fractions 3-5. Omissions tests established that ethyl 2-hydroxy-4-methylpentanoate was responsible for enhancing black-berry and fresh-fruit aroma and that a combination of diacetyl, acetoin, acetic acid, and γ-butyrolactone, at levels between 2 and 40% of their perception thresholds, had the same hypoadditive effect on the overall and fresh fruity aroma as fractions 3-5.
Journal of Agricultural and Food Chemistry 12/2012; · 2.82 Impact Factor
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ABSTRACT: The role of malolactic fermentation (MLF) in the fruity aroma of red wines was investigated by an analytical study on more than 60 volatile compounds in 48 red wines made in varied conditions and supplemented by a sensory study. Lactic acid bacteria (LAB) modify the fruity notes of red wines but without a specific trend. The absence, in the short-term, of a lactic mask was underlined whereas the existence of a smoked/toasted reduction-like mask note was evoked but not characterized. Variations in the composition of the fruity aroma markers were predominant. Although LAB β-glycosidase activities were not very involved, on the other hand, esterase seemed to play a central role that was sometimes associated with the metabolism of the sulfur-containing compounds. New insights in ester metabolism in oenological LAB and the importance of wine composition on bacterial variations in metabolites and aromatic alterations were emphasized.
Journal of Agricultural and Food Chemistry 11/2012; · 2.82 Impact Factor
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ABSTRACT: Wine experts usually rely on chemical tracers of qualities or defects to judge wines. While part of their expertise is determined
by their sensory ability to detect these key compounds, their level of sensitivity is generally unknown. The olfactory detection
thresholds for 10 key odorant compounds in wine were, therefore, measured in a large sample of professionals (100 < n < 150). The experts’ sensitivity to two tastants, tartaric acid and alum (respectively, sour and astringent compounds) was
also tested. The study confirms that distributions of individual detection thresholds were very large (>3 log10 units). Comparing
the abilities of the experts to detect the whole sample of chemicals tested, we showed that their sensitivity profiles were
very different. Detection threshold distribution asymmetries suggested specific hyposmias or hyperosmias for b-ionone, 2-isobutyl-3-methoxypyrazine, 2,4,6-trichloroanisole, diacetyl, and linalool. Interestingly, we found that academic
degrees in tasting and enology do have an impact on odor detection thresholds for two compounds, diacetyl and mixed ethylphenols.
KeywordsWine experts–Wine key compounds–Olfaction and taste–Detection thresholds–Qualified wine professionals
Chemosensory Perception 04/2012; 4(3):99-115. · 1.64 Impact Factor
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ABSTRACT: The enantiomers of ethyl 2-hydroxy-4-methylpentanoate (ethyl dl-leucate) were assayed in several wines using chiral gas chromatography (γ-cyclodextrin). Analyses of 55 commercial wines from various vintages and origins revealed different distributions. Generally, white wines presented only the R form, whereas red wines contained both enantiomers, in various ratios according to aging. The highest levels of the S form were found in the oldest samples. The R/S average enantiomeric ratio of this compound in red wine was approximately 95:5 with an average total concentration of ∼400 μg/L. The olfactory threshold of R-ethyl 2-hydroxy-4-methylpentanoate (126 μg/L) in hydroalcoholic solution was almost twice that of the S form (55 μg/L). The olfactory threshold of a mixture of R- and S-ethyl 2-hydroxy-4-ethylpentanoate (95:5, m/m) in hydroalcoholic solution was 51 μg/L, suggesting that both enantiomeric forms contribute to perception of this compound in wine, resulting in a synergistic effect. Both enantiomers have quite similar aromatic nuances. Sensory analysis was employed to demonstrate a synergistic effect of this ethyl ester on the perception of fruity aromas in wine: in hydroalcoholic solution supplemented with R- or S-ethyl 2-hydroxy-4-methylpentanoate or a mixture of the R and S forms (95:5, m/m) at their average concentrations in red wines, fruity character was perceived at concentrations 2.2, 4.5, and 2.5 times lower, respectively, than in hydroalcoholic solution alone. Sensory profiles of aromatic reconstitutions, using HPLC fruity fractions, highlighted the contribution of this compound to blackberry fruit and fresh fruit descriptors.
Journal of Agricultural and Food Chemistry 02/2012; 60(6):1503-9. · 2.82 Impact Factor
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ABSTRACT: A part of the "bouquet of wines" can be caused by the presence of odorous heterocycles produced by chemical reactions between S-amino acids and α-dicarbonyl compounds. Under wine ageing physic-chemical conditions (20 ± 2 °C, ethanol/water 12% v/v, pH 3.5), products of the diacetyl (DI) reaction with cysteine include a number of 1,3-N,S and 1-3-N,O 5 member heterocycles having methyl groups attached at C(2). The origin of this methyl-C(2) fragment was not clear; it could be supplied from DI or from cysteine. To explore this question, a parallel reaction was run in which DI was replaced by 3,4-hexanedione. With the C(1) and C(4) carbons of DI thus marked with methyl groups, the product distribution demonstrated that in the DI and cysteine reaction, both DI and cysteine provided the methyl-C(2) to varying degrees in the formation of 2-methylthiazole, 2-methyl-3-thiazoline and 2,4,5-trimethyloxazole but only cysteine supplied this fragment for 2-methylthiazolidine. The results are interpreted in terms of reaction paths appropriate for the mild conditions. These pathways shed light on the mechanisms leading from dicarbonyls to heterocyclic compounds. Like all the chemical pathways, they anticipate the impact of other compounds and physicochemical parameters on heterocyclic generations the generation of heterocyclics. They also suggest the presence of unexplored odorous compounds.
Journal of Food Science 07/2011; 76(6):C861-8. · 1.66 Impact Factor
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ABSTRACT: A simple and automated high performance liquid chromatography (HPLC) method for the separation and quantitative determination of gamma-glutamylcysteine and reduced glutathione (GSH) in wines is reported. This technique involves the use of a pre-column derivatization with 2,3-naphthalenedialdehyde (NDA), an isocratic separation in presence of beta-cyclodextrine and a fluorimetric detection. The quantification of oxidized glutathione (GSSG) has also been studied, for the first time in wines, using an additive pre-derivatization step for reduction using glutathione reductase. The method has been designed for use in laboratories with limited equipment. The assay has been optimized and presents very good performances in terms of sensitivity and selectivity. Then, it has been validated for linearity, LOD, LOQ, precision and accuracy.
Analytica chimica acta 02/2010; 660(1-2):158-63. · 4.31 Impact Factor
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ABSTRACT: A multi-residue method (MRM) for the detection and quantification of eight compounds responsible for off-flavours in wine using stir bar sorptive extraction (SBSE) followed by thermal desorption (TD) and gas chromatography-mass spectrometry (GC-MS) analysis is presented. The extraction and desorption conditions were optimised in order to get the best compromise for the simultaneous analysis of the eight target solutes, belonging to different chemical classes. The analytical conditions enable the quantification of the solutes below their respective organoleptic perception thresholds in wine. The method displayed good linearity over the concentration ranges explored in wine as well as excellent repeatability (RSD below 6%) and good reproducibility (RSD below 24%). The developed methodology was applied to the analysis of several wines and showed good agreement with the results collected with headspace solid-phase microextraction (HS-SPME) or liquid-liquid extraction (LLE) followed by GC-MS or electron capture detection (ECD). Good correlation was also found between the analytical and sensory results.
Journal of chromatography. A 03/2009; 1216(15):3318-27. · 4.19 Impact Factor
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ABSTRACT: The model reaction of cysteine and diacetyl under winemaking conditions resulted in the identification of over 40 products. Of these, 12 were also identified in wine samples. Several products of the model system contained unexpected structures that do not fit the four-carbon skeletal pattern of diacetyl. Possible synthetic routes to one of these products, trimethylpyrazine, are presented.
Annals of the New York Academy of Sciences 05/2008; 1126:216-9. · 3.15 Impact Factor
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ABSTRACT: The model reaction of cysteine and diacetyl under winemaking conditions resulted in the identification of over 40 products. Of these, 12 were also identified in wine samples. Several products of the model system contained unexpected structures that do not fit the four-carbon skeletal pattern of diacetyl. Possible synthetic routes to one of these products, trimethylpyrazine, are presented.
Annals of the New York Academy of Sciences 04/2008; 1126(1):216 - 219. · 3.15 Impact Factor
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ABSTRACT: Malolactic fermentation (MLF), which is conducted by lactic acid bacteria (LAB), has a significant influence on the stability and organoleptic quality of wine. Recent studies have shown that when MLF is carried out in oak wood barrels, LAB were also able to interact with wood and increase volatile compound contents such as vanillin during MLF. The release of these compounds indicates that LAB may convert vanillin precursors present in oak wood. In this work, the effect of commercial glycosidases on the released vanillin was firstly studied. This aldehyde is present in wood extracts in monoglycosidic forms where the major glycones are arabinose and xylose. Other aglycons released during MLF in barrels, syringaldehyde and whisky-lactones, can be considered as other sources of aroma. Secondly, strains selected with high activities toward glycoside substrates could hydrolyse vanillin glycoside precursors from oak wood with the same efficiency as commercial enzymes.
Food Microbiology 03/2008; 25(1):99-104. · 3.28 Impact Factor
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ABSTRACT: This report has investigated the seasonal temperatures influences (winter and summer) of five vineyards at different altitudes on the concentrations of 2-methoxy-3-isobutylpyrazine (MIBP), alpha- and beta-ionone, and beta-damascenone in 2004 or 2005 vintages of Cabernet Sauvignon wines from Santa Catarina State, Brazil. Sensorial analyses were also carried out on the wine samples and compared to altitude and climate. Significant regression was observed between MIBP concentrations and the vineyard's altitude. No significant relation was observed between alpha- and beta-ionone and beta-damascenone with the vineyard's altitude. Principal component analysis positively correlated wines from higher altitudes with a "bell pepper" aroma. Conversely, the wines made with grapes from lower altitudes were correlated with "red fruits" and "jam" aromas. An important relation between the bell pepper aroma and the lower winter temperature was observed. A strong negative correlation was also observed between seasonal temperatures and vineyard altitude as well as between MIBP content and seasonal temperature of growing grapevines.
Journal of Agricultural and Food Chemistry 05/2007; 55(9):3605-12. · 2.82 Impact Factor
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ABSTRACT: Under conditions close to those of wine, that is, low pH, aqueous medium, and low temperatures, this work describes N-(2-sulfanylethyl)-2-oxopropanamide (1), a new intermediate in the formation of 2-acetylthiazole from methylglyoxal and cysteine. 1 was characterized by MS, derivatization MS, and (1)H and (13)C NMR and was synthesized from 2-sulfanylethanamine and ethyl pyruvate. A formation pathway for 2-acetylthiazole from methylglyoxal and cysteine is proposed, in which 1 is a new intermediate in Maillard-type reactions in systems under mild conditions.
Journal of Agricultural and Food Chemistry 11/2002; 50(21):6160-4. · 2.82 Impact Factor
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ABSTRACT: Intramolecular gluconic acid esterification reactions led to the formation of two lactones, gamma- and delta-gluconolactone (glucono-1,4-lactone and glucono-1,5-lactone). The presence of the first has not yet been reported in must or wine. These lactones are in equilibrium with gluconic acid, gamma- and delta-gluconolactone representing, respectively, 5.8 and 4.1% of the acid level. Correlations between must SO(2) binding power, gluconic acid, and consequently its lactones are shown. The SO(2) affinity of a mixture containing this acid and gamma- and delta-gluconolactone was determined, and gluconic acid appeared to be indirectly responsible for approximately 8% of the bindable SO(2) in musts from botrytized grapes.
Journal of Agricultural and Food Chemistry 11/2002; 50(22):6408-12. · 2.82 Impact Factor
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ABSTRACT: This paper describes the study of 19 wines of the Grenache Noir cultivar obtained from representative soils of the Rhone Valley according to their geographical site, climatic conditions, hydrological regulation, and soil profile. Among the volatile compounds analyzed by GC/MS/FID, the concentrations of the varietal compounds (i.e., beta-damascenone, beta-ionone, and geraniol) and those of the compounds without direct influence on the wine aroma (i.e., hexenols and methanol) indicated the existence of two groups of wines. These concentrations were correlated with grape maturity due to the ecosystem and particularly the soil.
Journal of Agricultural and Food Chemistry 11/2002; 50(22):6341-5. · 2.82 Impact Factor
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ABSTRACT: Qualitative and quantitative analyses of N-heterocycle compounds were conducted by using a liquid-liquid extraction followed by additional chemical silica gel purification and injection into a gas chromatographic (GC) column coupled to a nitrogen-phosphorus detector (NPD). The purified extract fraction was investigated by GC-NPD and by GC-mass spectrometry. The compounds identified and quantified in wines were 2,4,5-trimethyloxazole, 2,4-dimethylthiazole, and 4-methylthiazole by GC-NPD and both 2-acetylthiazole and 2-acetyl-2-thiazoline by GC-MS. The procedure was used to analyze different wines and gave reliable and reproducible results.
Journal of Agricultural and Food Chemistry 11/2002; 50(21):5803-7. · 2.82 Impact Factor
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ABSTRACT: An analytical method for the determination of free amino acids and especially of cysteine in musts and wines is reported. This technique involves the use of a pre-column derivatisation with iodoacetic acid (IDA) and o-phthaldialdehyde (OPA). Isoindole-type fluorescent derivatives were formed in alkaline solution from OPA, 2-sulphanylethanol and the primary amine group of the amino acids. The derivatives were separated by HPLC using a linear multistep solvent gradient and were detected by spectrofluorimetry. This method is suitable for the separation of most free amino acids including cysteine. It allows high recovery and satisfies the necessary requirements with respect to accuracy, repeatability and sensitivity. The first application of this analytical method to the measurement of cysteine in musts and wines is reported.© 2001 Society of Chemical Industry
Journal of the Science of Food and Agriculture 05/2001; 81(8):731 - 738. · 1.44 Impact Factor
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ABSTRACT: Carbonyl compounds play an important role in musts from botrytized grapes. Some of them, such as glyoxal and methylglyoxal, may explain a considerable part of bindable SO2. Others, such as 2- and 5-oxogluconic acids, produced by gluconic acid oxidation in proportions respectively from 2.5 per 1 play an interesting role as SO2 binding indicator. Finally, the levels of some compounds such as dihydroxyacetone, 5-oxofructose, and δ-gluconolactone in balance with gluconic acid are well correlated with SO2 binding powers and also explain a large part of the bindable SO2 in musts. During alcoholic fermentation, only dihydroxyacetone among these three compounds is metabolized by yeast. Thus, two compounds present in grapes, δ-gluconolactone and 5-oxofructose, with three yeast SO2-binding byproducts, ethanal, pyruvic, and 2-oxoglutaric acids, explain much of the SO2 binding power in wines from botrytized grapes. Keywords: Sulfur dioxide; wine; botrytized grapes; SO2-binding compounds; carbonyl compounds
07/2000;
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ABSTRACT: A method to determine the most abundant α-dicarbonyl compounds in wine was developed by reaction with 2,3-diaminobenzene. Products such as quinoxaline derivatives were detected by high-performance liquid chromatography (HPLC) or by gas chromatography with a mass-selective detector (GC–MS) or a thermoionic detector (GC–NPD). HPLC and detection with a spectrophotometer (313 nm) were used for routine quantitative analysis of wines. The method is sensitive, linear and has good repeatability. Diacetyl, pentane-2,3-dione, glyoxal and methylglyoxal were quantified in a single run; these compounds are always encountered in wines, but levels vary with different types of wine and also during fermentation and maturation processes. A new dicarbonyl compound, phenylglyoxal, was found in wine. The evolution of dicarbonyl compounds during fermentation is reported in this paper.© 2000 Society of Chemical Industry
Journal of the Science of Food and Agriculture 01/2000; 80(1):102 - 108. · 1.44 Impact Factor
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ABSTRACT: The identification of a reductone found in sweet botrytized white table wines is described. A derivation method with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBOA), which permitted the identification of carbonyl and α-dicarbonyl compounds, was used. On the basis of analysis by GC and GC/MS and of 1H-NMR data, the compound has been identified as hydroxypropanedial. This triose reductone is possibly characterized by a large sulfur dioxide combination power and redox properties. The compound was isolated from musts and wines produced from botrytized grapes. It is normally present in very low concentrations in dry white or red wines, but this carbonyl compound occurs in huge levels if Botrytis cinerea and other damaging molds with associated moldy and acetic characters are present in spoiled berries. Keywords: Hydroxypropanedial; reductones; α-dicarbonyls; wine
09/1997;
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ABSTRACT: Wine aldehydes were identified as O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine derivatives by GC-MS or with a GC-electron-capture detector. This method has been used to evaluate levels of glyoxal and methylglyoxal in wine. Reproducibility and linearity studies gave satisfying results. Glyoxal and methylglyoxal are formed during fermentation. Among the factors affecting their production, high musts pH increased the levels found in the corresponding wines. Various microorganisms of the wine such as Saccharomyces cerevisiae and Leuconostoc ænos can produce glyoxal and methylglyoxal. The concentrations in Sherry wines were particularly high. Because of the toxicological properties of these substances, their determination and the knowledge of their metabolism by wine microorganisms are very important.
Journal of the Science of Food and Agriculture 12/1992; 61(2):267 - 272. · 1.44 Impact Factor
