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Stable isotope dilution analysis of wine fermentation products by HS-SPME-GC-MS
Abstract
The aim of this study was to quantify, in a single analysis, 31 volatile fermentation-derived products that contribute to the aroma of red and white wine. We developed a multi-component method based on headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC-MS). The 31 volatile compounds analysed include ethyl esters, acetates, acids and alcohols. Although these compounds have a range of functional groups, chemical properties, volatilities, affinities for the SPME fibre, and are found in wine at various concentrations, the accuracy of the analysis was achieved with the use of polydeuterated internal standards for stable isotope dilution analyses (SIDA). Nine of the labelled standards were commercially available, while 22 were synthesised. The method was validated by a series of duplicate spiked standard additions to model, white and red wine matrices over the concentration range relevant for each compound in wine. This demonstrated that the appropriate use of SIDA helped to account for matrix effects, for instance potential sources of variation such as the relative response to the MS detector, ionic strength, ethanol content and pH of different wine matrices. The resultant calibration functions had correlation coefficients (R 2) ranging from 0.995 to 1.000. Each compound could be quantified at levels below its aroma threshold in wine. Relative standard deviations were all SPME fibre, SPME temperature, SPME time, GC column and MS conditions. Confirmation of identity was achieved by retention time and peak shape, and measurement of at least three ions for each analyte and internal standard with the MS operating in selected ion monitoring mode to facilitate more precise quantitation with a high sampling rate. The method is a valuable research tool with many relevant applications. A novel method for the combined chiral separation and SIDA quantification of 2- and 3-methylbutanoic acid is also demonstrated.
... Analysis of fermentation products by solid phase microextraction/GC/MS analysis. The fermentation products (esters, carboxylic acids and higher alcohols) were analysed, according to Siebert et al. (2005) with some modifications, on an Agilent 7890A (Agilent Technologies, Palo Alto, CA, USA) GC equipped with a Gerstel MPS2 multi-purpose sampler and coupled to an Agilent 5975C VL single quadrupole mass spectrometer. The instrument was controlled with Agilent ChemStation vE.02.02.1431. ...
... The raw data from the Agilent ChemStation software were converted and processed using MassHunter Workstation software version B.04.00 (Agilent Technologies Australia, Mulgrave, Vic., Australia) for quantitative analysis. The concentration of analytes in the samples was determined using stable isotope dilution analysis (SIDA) (Siebert et al. 2005). ...
... Aside from methionol (OH7) which behaves differently as a sulfur-containing compound, the concentration of the higher alcohol, acid and ester did not vary significantly in the wines of either cultivar up to 12 months ( Figure 4). Considering that fermentation is the main source of higher alcohols, acids and esters, increases in these compounds in the sparkling wine would be expected and immediately after fermentation (i.e. the 6 month timepoint) (Siebert et al. 2005, Styger et al. 2011. Increases can only be observed, however, in the sparkling wine at 24 months in Chardonnay particularly with the larger acids and their corresponding esters but not at the earlier time points. ...
Background and Aims
Yeast autolysis is understood to be primarily responsible for giving traditional method sparkling wines complex and developed aromas. The contribution from ageing the wine itself, however, is less well-established. This study aimed to determine the contribution of autolysis products and compounds associated with wine oxidation and ageing in Vitis vinifera L. Chardonnay and Pinot Noir wines over 24 months.
Methods and Results
Chardonnay and Pinot Noir base wines were tiraged, or aged with and without primary lees. Volatile composition analyses (HS-SPME/GC/MS and GC/MS/MS) were conducted at 6, 12, and 24 months post-bottling and sensory appraisals at 12 and 24 months. The duration of ageing significantly influenced compositional changes in fermentation-derived and oxidative-flavour-associated compounds. Ageing base wines off or on lees produced similar maturation-associated aroma profiles to sparkling wines irrespective of cultivar.
Conclusions
The contribution of autolysis products did not feature as strongly as anticipated over 24 months, indicating that compounds associated with wine ageing primarily influenced the aroma of mature sparkling wines. This finding suggests winemakers ageing their wines on lees for 24 months or less should place more emphasis on base wine composition to manipulate the aroma profiles of sparkling wines.
Significance of the Study
First comparative chemical compositional study of base wines concurrently with sparkling wines.
... During fermentation, [Glucose + Fructose] concentrations were determined spectrophotometrically using a Randox kit (Randox Laboratories Ltd., Crumlin, Antrim, UK) with adaptations for use in a 96-well microplate format [41]. Volatile acetates, esters and higher alcohol concentrations in the finished wines were determined using large-volume, stable-isotope dilution headspace-GC/MS analysis (Metabolomics Australia, Adelaide Australia) as adapted from [42] and as described by [43]. Volatile sulphur compounds contributing sulfidic off-aromas, were determined by gas chromatography with sulphur chemiluminescence detection (GC/SCD) [42,44]. ...
... Volatile acetates, esters and higher alcohol concentrations in the finished wines were determined using large-volume, stable-isotope dilution headspace-GC/MS analysis (Metabolomics Australia, Adelaide Australia) as adapted from [42] and as described by [43]. Volatile sulphur compounds contributing sulfidic off-aromas, were determined by gas chromatography with sulphur chemiluminescence detection (GC/SCD) [42,44]. Aroma thresholds were in wine estimated using data from Siebert et al., [42] Free SO 2 was measured in grape juice supplemented with freshly prepared PMS using the aspiration/titration method [45]. ...
... Volatile sulphur compounds contributing sulfidic off-aromas, were determined by gas chromatography with sulphur chemiluminescence detection (GC/SCD) [42,44]. Aroma thresholds were in wine estimated using data from Siebert et al., [42] Free SO 2 was measured in grape juice supplemented with freshly prepared PMS using the aspiration/titration method [45]. ...
Uninoculated wine fermentations are conducted by a consortium of wine yeast and bacteria that establish themselves either from the grape surface or from the winery environment. Of the additives that are commonly used by winemakers, sulphur dioxide (SO2) represents the main antimicrobial preservative and its use can have drastic effects on the microbial composition of the fermentation. To investigate the effect of SO2 on the resident yeast community of uninoculated ferments, Chardonnay grape juice from 2018 and 2019 was treated with a variety of SO2 concentrations ranging up to 100 mg/L and was then allowed to undergo fermentation, with the yeast community structure being assessed via high-throughput meta-barcoding (phylotyping). While the addition of SO2 was shown to select against the presence of many species of non-Saccharomyces yeasts, there was a clear and increasing selection for the species Hanseniaspora osmophila as concentrations of SO2 rose above 40 mg/L in fermentations from both vintages. Chemical analysis of the wines resulting from these treatments showed significant increases in acetate esters, and specifically the desirable aroma compound 2-phenylethyl acetate, that accompanied the increase in abundance of H. osmophila. The ability to modulate the yeast community structure of an uninoculated ferment and the resulting chemical composition of the final wine, as demonstrated in this study, represents an important tool for winemakers to begin to be able to influence the organoleptic profile of uninoculated wines.
... The base wine with no lees added back was still run through 'disgorgement' for consistency of air exposure during this process. Forty-six analytes were identified and quantified from bottled wines as described by Siebert et al. (2005) and Mayr et al. (2015) with some modifications. For the Siebert et al. (2005) method, the injector temperature was set at 260°C and the oven temperature started at 40°C, then increased to 60°C at 20°C/min (held for 14 min), followed by a series of temperature ramps. ...
... Forty-six analytes were identified and quantified from bottled wines as described by Siebert et al. (2005) and Mayr et al. (2015) with some modifications. For the Siebert et al. (2005) method, the injector temperature was set at 260°C and the oven temperature started at 40°C, then increased to 60°C at 20°C/min (held for 14 min), followed by a series of temperature ramps. The first ramp was to 70°C at 10°C/min, the second ramp was to 80°C at 10°C/min, the third ramp was to 160°C at 20°C/min, and the final ramp was to 260°C at 10°C/min and held for 2 min. ...
Receptomics is a novel bio-analystical approach based on parallel screening of large numbers of biological recpetors to evaluate potential bioactives, such as aroma and taste compounds. It also holds promise to augment or replace human sensory evaluation of food and beverages. This paper describes a novel microfluidic technique developed in Wageningen for anlaysis of complex liquitd food samples against large arrays of human sensory and health-related receptors- expressed in a human cell line, inside a flow cell. A small pre-study on the analysis of red and white wine against a nearly complete set of bitter receptors is also reported. To ensure the cells would tolerate undiluted wine, it was necessary to first neutralisee the wine pH and remove the alcohol. To observe specific activation of receptors, the 16-times diluted sample was contrasted with the 2-, 4- and 8-times diluted samples. Surprisingly, it was found that both Shiraz and Gewurztraminer wines induced at higher concentrations a negative signal with some of the receptors that were expected to give positive signals (TAS2-R4, -R7, -R39 and -38PAV) in this two wines. This is somewhat unexpected in light of pure compound assays and observations in other bitter drinks such as beer and coffee. The lack of positive signals may be due to the fact that the pH was adjustd and/or that the assay lacked sensitivity as it was only possible to analyse diluted wine. To further evaluate the potential of receptomics for direct analysis of wine taste, it will be required to (i) identify and correct for the dip-inducing factor (ii) analyse non-bitter wines after the addition of bitter compounds as positive controls and compare them to bitter wines, and (iii) repeat the tests with pH-insensitive reporters of receptor activation.
... Volatile compounds. Volatile analytes in wine selected on the basis of known contributions to varietal aroma were quantified by headspace solid-phase microextraction with gas chromatography-mass spectrometry (HS-SPME-GC-MS) detection using single ion monitoring (SIM) acquisition and quantitation as reported in Siebert et al., (2005). Analytes were calibrated against standards prepared in a model wine solution using deuterated and structurally similar compounds not naturally present in wines as internal standards. ...
... This was injected on an Agilent 6890 gas chromatograph coupled to a 5975C inert XL mass spectrometer (MS) (Agilent Technologies Inc., Santa Clara, CA, USA). Conditions and qualifier and quantifier ions were the same as reported in Siebert et al., (2005). ...
Grape ripening accelerates under warmer and drier conditions, resulting in the accumulation of sugars (‘technological’ maturity) being decoupled from phenolic and aromatic composition. This study investigated the effect of different rates of ripening on the composition of Cabernet Sauvignon and Riesling wines. Manipulating crop load and irrigation led to distinct rates of berry ripening. In the resulting wines, reduced crop load affected the aroma composition, altering the profile and abundance of grape-derived compounds and fermentative esters. Phenolic composition was impacted by the irrigation regime, with color and tannin increased by late season irrigation. In Cabernet Sauvignon, the combination of treatments led to the largest ripening delay (3 weeks), resulting in less green and more fruity compounds, and improved phenolic composition. By mapping grape and wine metabolites and exploring their relationship, the outcomes of this study demonstrate the importance of ripening rates in determining wine quality.
... Concentrations of 2-methylbutyl acetate met 129-200 mg/L in white wines and 181-359 mg/L in red wines [39], while 0.38 mg/L (Ili River valley)-1.58 mg/L (Shihezi) in the experimental samples, which was usually associated with banana and fruity descriptors, and the olfactory threshold was 5 mg/L in water and 160 mg/L in wine [39][40][41]. Previous reports on a correlation between 2-methylbutyl acetate and 2-methylbutan-1-ol demonstrated that the formation of the ester depended on the corresponding higher alcohol [40,42]. ...
... mg/L (Shihezi) in the experimental samples, which was usually associated with banana and fruity descriptors, and the olfactory threshold was 5 mg/L in water and 160 mg/L in wine [39][40][41]. Previous reports on a correlation between 2-methylbutyl acetate and 2-methylbutan-1-ol demonstrated that the formation of the ester depended on the corresponding higher alcohol [40,42]. e results in every region catered to the above researches further. ...
A total of 55 volatiles including esters (29, 52.73%), alcohols (10, 18.18%), acids (3, 5.45%), alkanes (8, 14.55%), and other components (5, 9.09%) were evaluated in five regions. Total concentrations were 0.05–222.23 mg/L, which covered the highest esters (222.23 mg/L) and alcohols (120.65 mg/L) in Turpan, acid (0.53 mg/L) in Shihezi, and alkanes (1.43 mg/L) and others (3.10 mg/L) in the Ili River valley. It proved that numbers and concentrations of volatile compounds, including common ingredients of variety, were closely linked to ecological characteristics of a region. Esters and alcohols were the major ingredients in Xinjiang Cabernet Sauvignon wine. Additionally, appellation could affect performance of concentration, ODE, and OTH, especially for the same flavor substance by fermentation, aging, and even formation and transformation in wines. Therefore, three conditions for formation of flavors were successively appellations, metabolism and fermentation, and and appropriate altering according to technology and their decisive role in wine quality. Each volatile compound had its own flavor, the combination of which complicated the flavor. The unique materials in the region were grounded for the development of products with corresponding flavors by producing substrate for fermentation. When choosing a wine you enjoy, the right appellation should be considered first.
... Siebert et al. [59] first proposed the use of polydeuterated internal standards for stable isotope dilution analyses of 31 wine fermentation products by HS-SPME-GC/MS. Nine of the labelled standards were commercially available while 22 were synthesized. ...
... Capone et al. [60] developed a SIDA method for the quantitative analysis of seven C6 compounds. The two methods above [58,59] were successfully used by Ugliano et al. [61] and Bindon et al. [62]. Furthermore, Bindon et al. quantified isobutyl methoxypyrazine (IBMP), isopropyl methoxypyrazine (IPMP) and sec-butyl methoxypyrazine (SBMP) using IBMP-d3 as an internal standard. ...
The aim of this review is to explore and discuss the two main aspects related to a HeadSpace Solid Phase Micro-Extraction Gas-Chromatography/Mass-Spectrometry (HS-SPME-GC/MS) quantitative analysis of volatile compounds in wines, both being fundamental to obtain reliable data. In the first section, recent advances in the use of multivariate optimization approaches during the method development step are described with a special focus on factorial designs and response surface methodologies. In the second section, critical aspects related to quantification methods are discussed. Indeed, matrix effects induced by the complexity of the volatile profile and of the non-volatile matrix of wines, potentially differing between diverse wines in a remarkable extent, often require severe assumptions if a reliable quantification is desired. Several approaches offering different levels of data reliability including internal standards, model wine calibration, a stable isotope dilution analysis, matrix-matched calibration and standard addition methods are reported in the literature and are discussed in depth here.
... Il s'agit souvent de méthodes dosant une large gamme de composés de familles différentes dont les esters font partie. Les étalons internes alors employés ne sont pas spécifiques aux esters, ce qui entraîne un manque de précision et de robustesse certain(Siebert et al., 2005). Ce constat est encore plus vrai, lorsqu'il s'agit de méthodes employant les techniques de microextraction sur phase solide. ...
... Or, il a été vu précédemment qu'il existait certaines différences dans les profils d'adsorption entre les différentes familles d'esters. Ainsi, plusieurs étalons internes sont nécessaires pour couvrir toute la gamme des esters dosés par cette regard des conditions de sélection d'un étalon interne précédemment évoqué, mais pourtant il reste encore très utilisé même pour des méthodes par microextraction sur phase solide.Certains auteurs ont déjà reporté l'utilisation d'esters deutérés pour l'analyse d'esters dans les vins(Siebert et al., 2005). Ainsi, 5 esters deutérés ont été retenus pour représenter au étant pas commercialisés et pour des raisons économiques, il a été choisi de les synthétiser au laboratoire à partir du chlorure d'acyle correspondant et de l'éthanol-d 6 . ...
L’objectif de cette thèse est d’étudier le rôle de la fermentation malolactique (FML) sur l’arôme fruité des vins rouges. Les bactéries lactiques (BL) modifient la composition du vin mais il n’existe pas de consensus concernant spécifiquement cette famille aromatique. Contrairement aux idées empiriques sur la FML, ce travail a démontré l’absence à court terme d’un " masque lactique ", cependant l’apparition d’une telle interaction olfactive pourrait être plus tardive. Par contre, il est montré l’existence d’un masque proche de la note de réduction, de type fumé/grillé, dont la caractérisation n’a pas été effectuée dans cette étude.Le suivi des principaux marqueurs fruités du vin (70 molécules) a été rendu possible par le développement des méthodes d’analyse chromatographique en phase gazeuse couplée à la microextraction sur phase solide (esters, C13-norisoprénoïdes, lactones, thiols). En particulier, une " base de données esters " (32 composés) a rendu plus robuste l’ensemble des variations constatées au cours du développement des BL. En effet, les modifications des teneurs en esters sont démontrées comme un processus majeur de la balance de la note fruitée au cours de la FML. Cette fermentation permet à court terme, aussi bien la synthèse que l’hydrolyse des esters grâce aux activités estérases et, à plus long terme, la formation tardive d'esters éthyliques d'acides branchés issus du catabolisme de certains acides aminés. La spécificité des estérases vis-à-vis de la nature et de la longueur de la chaîne carbonée des esters est mise en évidence, ainsi que l'importance de la disponibilité des substrats, liée en partie à l'activité des levures.L’étude de l’influence des souches de BL et de la co-inoculation levures/bactéries a permis de confirmer le rôle clé des interactions entre les microorganismes, ainsi que l’importance de la composition de la matrice vin.
... Generally, acetic acid is responsible for the pungent odor in vinegar [18]. Huh et al. [21] reported that high acetic acid content could decrease the taste of a liquor, although the threshold for acetic acids is approximately 280,000 μg/L in a 10% ethanol system [22]. Among the 12 samples, Y4 had the highest acetic acid content (14,700 μg/L) followed by Y8 (5038 μg/L), while Y12 had the lowest acetic acid content (624 μg/L). ...
... Volatile alcohol compounds have a pungent mouthfeel and a pungent and "herbaceous" odor [43]. Described as having a grassy, medicinal, fusel, and spirituous odor, 1-butanol has an odor threshold of 150,000 μg/L [22,43,44]. Although 1-butanol correlated with consumers' acceptance, the odor of 1-butanol may be imperceptible considering that the 1-butanol contents in the samples ranged from 44.8 μg/L to 1,159.9 μg/L, which was considerably lower than the threshold value. ...
The sensory characteristics and volatile compounds that affect consumers’ acceptance of rice liquors were investigated. A total of 80 consumers evaluated 12 yakju samples and descriptive analysis by 11 trained panelists was conducted. Solvent-assisted flavor evaporation-gas chromatography-mass spectrometry analysis also was conducted revealing 120 volatile compounds in the yakju samples. Sensory attributes (n = 31) except appearance attributes were used for principal component analysis (PCA). As results, fruit odor (apple, hawthorn, omija, and pineapple odor) and flower odor (chrysanthemum, pine, and peppermint odor) were placed on the positive side of PC1 whereas persimmon vinegar odor, bitter taste, alcohol flavor, stinging and coating mouthfeel were located on the negative side of PC1. The yakju samples were mainly characterized by their alcohol content and supplementary ingredients. Sensory descriptors (n = 31; except appearance attributes and p > 0.05) and volatile compounds (n = 30; p > 0.5 correlation coefficient with overall acceptance) were chosen for multiple factor analysis (MFA). The MFA correlation map showed that ethyl propanoate, ethyl-2-hydroxy-2-methylbutanoate, methyl 2-furoate, γ-butyrolactone, 4-ethoxycarbonyl-γ-butyrolactone, hawthorn odor, apple flavor, grape flavor, and sweet taste were positively correlated with young consumers’ overall acceptance. Additionally, negative correlation with overall acceptance was found in 1,3-butanediol, 2,3-butanediol, and 1,1-diethoxy-3-methylbutane.
... The concentrations of several fermentation volatiles (acids, alcohols and esters) were determined (without replication, i.e., n = 1) by Metabolomics Australia (AWRI) using an Agilent 7890A gas chromatograph, equipped with a Gerstel MPS2 multipurpose autosampler and coupled to an Agilent 5875C mass selective detector, and previously reported stable isotope dilution analysis (SIDA) methods [20]. Headspace solid phase micro-extraction (HS-SPME) sampling of diluted wine (1 in 10 dilution in water) was performed in a 20 mL vial containing 2 g of sodium chloride, with the SPME fiber being exposed to the headspace for 10 min prior to desorption. ...
... × 0.25 µm film thickness) and helium as the carrier gas (2.0 mL/min in constant flow mode). Preparation of isotopically labelled internal standards, method validation and instrument operating conditions are described extensively in the aforementioned publication [20]. ...
Warmer growing seasons, variations to grape ripening dynamics, and stylistic changes have contributed to increased wine alcohol levels, which can negatively impact sensory properties. As a consequence, winemakers have sought technological innovations to produce reduced alcohol wine (RAW). The sensory methodology used by industry to optimize the ethanol content of RAW is known as ‘alcohol sweetspotting’. However, to date, there is no scientific evidence to support the alcohol sweetspot phenomenon, and the sensory methodology used for alcohol sweetspotting has not been validated. In this study, different methods of presenting wine samples (i.e., ordered vs. randomized, and linear vs. circular) were employed to determine to what extent presentation order influences the outcome of alcohol sweetspotting trials. Two different approaches to statistical analysis of sensory data, i.e., chi-square goodness of fit vs. one proportion tests, were also evaluated. Statistical analyses confirmed alcohol sweetspots were apparent in some sweetspot determination trials, but outcomes were not reproducible in replicate determinations (either by panel or by individual panelists). Analysis of data using the one proportion test improved the likelihood of identifying statistically significant differences between RAWs, but variation in individuals’ sensitivity to differences in sensory properties following ethanol removal prevented validation of the alcohol sweetspot phenomenon based on the wines studied.
... bulgaricus and Streptococcus thermophilus. This suggests that the fermented milk beverages obtained in this study will not have unpleasant notes of vinegar or sourness [43,44]. ...
Nowadays, there has been a significant rise in the consumption of kefir, a functional beverage touted for its perceived health benefits. To offer a high-quality beverage to consumers, it is imper-ative to scrutinize and fine-tune the fermentation process. This study seeks to investigate the im-pact of fermentation time and the number of subcultures on the physicochemical, microbiological, and volatile composition, as well as the visual appearance of kefir beverages obtained from four consecutive 24- or 48-h batch subcultures. All fermented beverages exhibited low lactose, ethanol and acids levels, with counts of viable probiotic lactic acid bacteria and yeast exceeding 106 colony forming units/mL. The four kefir beverages from the 48-h batch subcultures notably showed the lowest total concentrations of volatile compounds likely due to overfermentation and overacidifi-cation of the beverages. This caused separation of the whey and curd, along with the formation of large gas bubbles, negatively affecting the visual appearance of the products. These findings em-phasize the importance of fine-tuning the fermentation process to ensure the production of high-quality kefir beverages that align with consumer preferences. The four beverages from the 24-h batch subcultures exhibited high microbiological and physicochemical stability during stor-age at 4 °C for 28 days.
... Overall, these results align with previous investigations, highlighting the contribution of both accelerated autolysis and Alcalase treatments in liberating intracellular components during the treatment process (Jacob et al., Values are mean (sd) of 3 incubation replicates. b Odour descriptors obtained from the literature (Siebert et al., 2018;Siebert et al., 2005). LOD: Limit of detection. ...
Extensive research has been dedicated to elucidating the role of various nitrogen sources, nitrogen concentrations and the timing of addition when modulating grape must fermentation using yeast. The wine industry invests substantial resources in both the vineyard and the winery to provide adequate nitrogen concentrations for fermentation. This approach ensures optimal yeast performance during fermentation and minimises the risk of negative sensory attributes associated with poor ferment nutrition. In addition to wine, the winemaking process produces a substantial quantity of nutrient-rich biomass, a poorly explored resource that, if appropriately recycled, could be used to support the nutrient requirements of other winery fermentations. This study explored the feasibility of using processed yeast lees generated during alcoholic fermentation as a nutrient supplement in subsequent fermentations. Three lees treatment options were assessed: accelerated autolysis, enzymatic lysis and mechanical lysis. The ability of these treatments to achieve complete lysis of yeast cells and release amino acids and trace elements is reported. The addition of processed lysates into grape juice was shown to improve fermentation timeframes and influence the production of yeast-derived fermentation volatile compounds in a dose-dependent manner. This study demonstrates that recycling spent lees from winery waste is feasible and provides some strategies for extracting nutrients from winery waste.
... An Agilent 7890B GC (Agilent Australia Pty Ltd., Mulgrave, VIC, Australia) was coupled to an Agilent 5977B MS and equipped with a Gerstel MPS Robotic Pro (Lasersan Australasia). Fermentation-derived aroma compounds were analysed by headspace solid phase microextraction (HS-SPME-GC-MS) (Siebert et al., 2005). The samples were analysed using an Agilent 7890A GC combined with an Agilent 5975C MS and Gerstel MPS2 multipurpose sampler. ...
Proline has recently been found to direct several sensory attributes in red wine, including viscosity, fruit flavour and sweetness. We sought to investigate whether a red wine, deemed ‘flavour deficient’ by a producer, from a warm inland region could be improved by blending with a high proline wine from the same region, compared to a high colour and flavour wine, linking consumer acceptance with sensory properties and chemical composition. Three dry red wines (two Cabernet-Sauvignon wines from a warm region and one Lagrein wine from a cooler region) were blended in a constrained mixture design. Several blends were uncovered with improved sensory properties and consumer liking scores. Increased liking scores were related to heightened perceived Viscosity (unrelated to physical viscosity), Sweetness and Berry flavours, connected to proline-rich wines with small proportions of Lagrein. PLS-R models relating blend chemical composition, sensory properties and consumer acceptance associated Astringency and Bitterness to polyphenolics and organic acids and lower liking scores. Vegetal and Leather aromas in blends also reduced consumer acceptance and were related to the concentration of the thiols 3SH, 3SHA, PMT, 2FMT and MeSH, as well as guaiacol and isobutyl methoxypyrazine. Multiple blends successfully improved consumer acceptance of the ‘flavour deficient’ wine, particularly those with an increased proportion of the proline-rich wine. Non-linear effects resulting from blending were also assessed, with most variables modelled best by linear averaging. This study demonstrates the practical application of a design of experiment approach using sensory properties, proline and polyphenolic concentrations to guide wine blending and improve wine flavour and acceptability.
... Te following analyses were only conducted on the subset of 24 wines. Fermentation-derived aroma compounds were analysed by headspace (HS)-solid phase microextraction (SPME)-GC/MS as described by Siebert et al. [33] except using a polyacrylate (PA, white) 85 μm SPME fbre (Supelco, Sigma-Aldrich), a VF-624 ms (30 m × 0.25 mm × 1.4 μm; Agilent) GC column, and an Agilent 7890A GC (Agilent Technologies Australia, Mulgrave, Vic., Australia) coupled to an Agilent 5975C MS and equipped with a Gerstel MPS2 multipurpose sampler (Lasersan Australasia, Tanunda, SA, Australia). Monoterpenes and C13norisoprenoids were analysed according to Pisaniello et al. [34] using membrane-assisted solvent extraction (MASE)-GC/MS on an Agilent 7890B GC, coupled to an Agilent 5977B MS and equipped with a Gerstel MPS Robotic Pro (Lasersan). ...
Background and Aims. A wide range of Chardonnay styles exist on the market, from fruit-forward examples to wines displaying “empyreumatic” aromas such as flint, smoky, mineral, and struck-match. The thiols 2-furylmethanethiol and phenylmethanethiol have been linked to these aromas, and this study aimed to determine the contribution of these compounds to specific sensory properties in Chardonnay wines, as well as the consumer acceptance of wine displaying “empyreumatic” aromas. Methods and Results. Twenty-four Australian and New Zealand Chardonnay wines were selected for volatile analysis and quantitative sensory descriptive analysis. Consumer liking of a subset of six wines was also determined, and a further sensory study involving additions of the thiols to a base wine was conducted. Partial least squares regression showed that flint/struck-match/mineral aromas were related to 2-furylmethanethiol concentration with phenylmethanethiol less well associated. The odorant addition study confirmed that 2-furylmethanethiol directed flint/struck-match/mineral aromas and exerted strong suppression of other aromas while phenylmethanethiol played a lesser role. Consumer acceptance (n = 92) was overall lower for wines displaying high flint/struck-match/mineral aromas, although cluster analysis of the liking scores identified a sizeable consumer group (33%) who preferred wines with this attribute. Conclusions. The potent thiol 2-furylmethanethiol was indicated to be the primary contributor to flint/struck-match/mineral aromas in Chardonnay wines, with phenylmethanethiol playing a subordinate role. Significance of the Study. Increased concentration of 2-furylmethanethiol and the conferred “empyreumatic” odours should be carefully considered when producing wine styles to appeal to consumers.
... 2.6.4 GCMS analysis of volatile phenol compounds GCMS was used to quantify the volatile phenols extracted from the grapes using standard isotope dilution assay (SIDA, Siebert et al., 2005). The method was adapted from the Oberholster lab at University of California, Davis (unpublished). ...
The frequency and intensity of wildfires have been increasing over the last 50 years and negatively impacted the wine industry. Previous methods of smoke mitigation during grape processing have shown little impact in reducing smoke taint in wines. Therefore, a novel method of using edible spray coatings for vineyard application was developed to help prevent volatile smoke phenol uptake in wine grapes. Four cellulose nanofiber‐based coating suspensions incorporated with chitosan and/or β‐cyclodextrin were evaluated. Films derived from the coating suspensions were exposed to volatile phenols found in wildfire smoke (guaiacol, 4‐methyl guaiacol, m‐cresol, o‐cresol, p‐cresol, syringol, and 4‐methyl syringol) and evaluated with ultraviolet‐visible spectroscopy where the results indicated that the coatings could uptake smoke phenols in varying degrees. The coatings were also applied in a vineyard at three different application times during grape growth: pea‐sized, pre‐bunch closure, and both at pea‐sized and pre‐bunch closure. The results showed that the application time did not have a significant (p < 0.05) effect on berry size, weight, °Brix, pH, or titratable acidity. The type of coating, time of application and washing were found to impact the number of volatile phenols in the grapes after a smoke event. Results from this study indicated that edible coatings could help mitigate smoke uptake in wine grapes without sacrificing the growth and key composition parameters of wine grapes.
Practical Application
This research provides a novel spray coating that can be applied to wine grapes in the vineyard to potentially mitigate volatile smoke compounds in wine grapes without impacting fruit growth and key compositional parameters of wine grapes, thus maintaining high quality of wines for consumers. Results from this study can also be potentially applied to other agricultural commodities to solve the issues caused by the wildfire smoke.
... Qualitative analysis of condensate samples collected during SCC treatment of smoketainted wines was performed by Metabolomics Australia (AWRI, Adelaide, SA, Australia) using headspace-solid phase microextraction (HS-SPME) [54]. Briefly, samples (diluted to~1% abv, with water, and saturated with 2.0 g of sodium chloride) were extracted with a DVB/CAR/PDMS SPME fiber (Sigma Aldrich, North Ryde, NSW, Australia) for 15 min at 40 • C, prior to desorption (in splitless mode), at an injector temperature of 260 • C, onto an Agilent 7890 A gas chromatograph fitted with an Agilent DB-624UI column (30 m × 0.25 mm × 1.4 µm) equipped with a Gerstel MPS2 multi-purpose autosampler, and coupled to a 5975C VL mass selective detector. ...
Where vineyard exposure to bushfire smoke cannot be avoided or prevented, grape and wine producers need strategies to transform smoke-affected juice and wine into saleable product. This study evaluated the potential for spinning cone column (SCC) distillation to be used for the remediation of ‘smoke taint’. Compositional analysis of ‘stripped wine’ and condensate collected during SCC treatment of two smoke-tainted red wines indicated limited, if any, removal of volatile phenols, while their non-volatile glycoconjugates were concentrated due to water and ethanol removal. Together with the removal of desirable volatile aroma compounds, this enhanced the perception of smoke-related sensory attributes; i.e., smoke taint intensified. Stripped wines also became increasingly sour and salty as ethanol (and water) were progressively removed. A preliminary juice remediation trial yielded more promising results. While clarification, heating, evaporation, deionization and fermentation processes applied to smoke-tainted white juice gave ≤3 µg/L changes in volatile phenol concentrations, SCC distillation of smoke-tainted red juice increased the volatile phenol content of condensate (in some cases by 3- to 4-fold). Deionization of the resulting condensate removed 75 µg/L of volatile phenols, but fermentation of reconstituted juice increased volatile phenol concentrations again, presumably due to yeast metabolism of glycoconjugate precursors. Research findings suggest SCC distillation alone cannot remediate smoke taint, but used in combination with adsorbents, SCC may offer a novel remediation strategy, especially for tainted juice.
... Aroma compounds in wine samples were extracted using headspace solid-phase microextraction (SPME) with a divinylbenzene/carboxen/ polydimethylsiloxane (DVD/CARC/PDMS) fiber assembly (Supelco, Bellefonte, PA, USA) and analyzed by GC-MS as described by Siebert et al. (2005), with some modifications. Analyses were performed using a Hewlett Packard 6890 gas chromatograph (Agilent Technologies) equipped with a HP 5975 mass selective detector, CTC Combi Pal autosampler and a DB-5 ms DG 30 m × 0.250 mm I.D., 0.5 µm film thickness (J&W Scientific, Santa Clara, CA). ...
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.
... Fermentation-derived aroma compounds analysed by headspace (HS)-solid phase micro-extraction (SPME)-GC/ MS as described by Siebert et al. (2005) using an Agilent 7890A GC (Agilent Technologies Australia, Mulgrave, Vic., Australia), coupled to an Agilent 5975C MS, and equipped with a Gerstel MPS2 multipurpose sampler (Lasersan Australasia, Tanunda, SA, Australia). Monoterpenes and C13-norisoprenoids were analysed according to Pisaniello et al. (2022) using membrane-assisted solvent extraction-GC/MS on an Agilent 7890B GC, coupled to an Agilent 5977B MS and equipped with a Gerstel MPS Robotic Pro (Lasersan) (Pisaniello et al. 2022). ...
The effect of amino acids, and their interactions with volatiles and other non‐volatiles, on in‐mouth sensory properties of red wines is not known. This knowledge gap has been studied in a series of comprehensive sensory experiments. A solvent‐assisted flavour evaporation extract of Shiraz wine volatiles, a de‐aromatised polyphenolic extract and amino acids were added to model wine and wine systems. Using full factorial designs, samples were evaluated by sensory quantitative descriptive analysis. Volatiles enhanced Viscous mouthfeel (F = 20.0, P < 0.001), Sweetness (F = 26.5, P < 0.001) and Body (F = 81.4, P < 0.001), while the phenolic extract directed Astringency (F = 170.5, P < 0.001) as well as Bitterness (F = 7.3, P < 0.001) and suppressed Sweetness (F = 16.5, P < 0.001). An amino acid by volatile interaction (F = 4.2, P < 0.05) was found, and further experiments showed that L‐proline enhanced Viscosity (F = 5.0, P < 0.05), Sweetness (F = 14.4, P < 0.001), Red fruit flavour (F = 7.8, P < 0.001) and suppressed Astringency (F = 6.1, P < 0.05) and Bitterness (F = 7.0, P < 0.01), while L‐glutamic acid imparted an Umami taste (F = 5.0, P < 0.05) at wine‐like concentration. For the first time, these causal experiments showed that amino acids can influence the taste, mouthfeel and flavour of red wine. This work provides insight into a new class of wine compounds of sensory significance that can be targeted by producers to directly influence wine flavour.
... The first colum was a Rtx-wax colum (30m, 0.2 mm ID, 0.5 μm film thickness, Restek Corportation, Bellefonte, PA, USA) and the second GC contained two columns connected in sequence: an Rt®-βDEXsm and an Rt®βDEXse (60 m, 0.25 mm ID, 0.25μm film thickness, Restek Corportation). The isomers were quantified using the standard curves and the stable isotope dilution analysis method (Siebert et al., 2005). All of the wines were run in three groups based on their styles (dry, medium dry and medium sweet) according to the wine label or available information for instrument analysis. ...
Monoterpenes are important characteristic compounds for aromatic white wines, including Riesling, but their enantiomer composition has been little explored in wine. Enantiomers can differ depending on region and style, as they are sensitive to environmental factors, and thus could be used for wine authentication. Thirteen monoterpene isomers were quantified by HS-SPME-MDGC-MS in fifty-four commercial Riesling wines from three wine styles (dry, medium dry and medium sweet) and four well-established wine-growing regions in Germany, France (Alsace) and the USA (New York and Oregon). Significant differences were found for nine out of the 13 enantiomers among different regions and eight enantiomers among styles. X-Y scatterplots of enantiomer pair concentrations, with excellent fitted lines, implies low variation of enantiomeric ratios from each region. The study suggests that wines from different regions and styles were differentiated by chiral monoterpene profiles. Chiral monoterpene analyses could provide supporting information in Riesling wine authentication by offering an objective measure of flavour quality, as these compounds are key compounds for Riesling aroma and flavor.
... thegoodscentscompany.com; VII. Siebert et al. (2005). (2015). ...
Non- Saccharomyces yeasts usually have a positive effect on improving the diversity of wine aroma and increasing the differentiation of wine products. Among these non- Saccharomyces yeast species, Torulaspora delbrueckii is often studied and used in winemaking in recent years, but its application in icewine has not been reported yet. In this study, indigenous T. delbrueckii strains (TD1 and TD2) and Saccharomyces cerevisiae strains (commercial yeast SC1 and indigenous icewine yeast SC2) were sequentially inoculated for icewine fermentations; meanwhile, pure S. cerevisiae (SC1 and SC2) fermentations were used as the control; TD1, TD2, and SC2 strains used were screened from spontaneous fermentations of Vidal blanc icewine. The aim was to investigate the effect of T. delbrueckii on the aroma complexity of icewine, which is of great significance to the application of T. delbrueckii in icewine production. The results showed that T. delbrueckii was completely replaced by S. cerevisiae at the middle and later fermentative stages in mixed culture fermentations. Compared with the icewine fermented with pure S. cerevisiae , mixed culture fermented icewines contained lower acetic acid and ethanol, and higher glycerol. The inoculation of T. delbrueckii greatly impacted the levels of several important volatile compounds, and more 2-phenylethyl alcohol, isoamyl acetate, linalool, D-limonene, p-cymene and cineole were produced, and the fruity, flowery, and sweet characteristic was intensified. Moreover, the relevance of strain-specificity within T. delbrueckii to aroma compound differences was shown. To our knowledge, this study is the first to investigate the application of T. delbrueckii in Vidal blanc icewine fermentation, and volatile aroma compounds in the icewine fermented by T. delbrueckii and S. cerevisiae .
... Oenococcus oeni shows several metabolic pathways and enzymes involved in volatile secondary compound production, including esters, higher alcohols, carbonyls, volatile fatty acids, and sulfur compounds (Bartowsky, 2005;Siebert et al., 2005). ...
In this study, nine Oenococcus oeni strains were tested for their ability to adhere to polystyrene using mMRS and wine as culture media. Moreover, planktonic and biofilm-detached cells were investigated for their influence on malic acid degradation kinetics and aroma compound production. Three strains were able to adhere on polystyrene plates in a strain-dependent way. In particular, MALOBACT-T1 and ISO359 strains mainly grew as planktonic cells, while the ISO360 strain was found prevalent in sessile state. The strain-dependent adhesion ability was confirmed by confocal laser scanning microscopy. Planktonic and biofilm detached cells showed a different metabolism. In fact, biofilm-detached cells had a better malic acid degradation kinetic and influenced the aroma composition of resulting wines, acting on the final concentration of esters, higher alcohols, and organic acids. Oenococcus oeni in biofilm lifestyle seems to be a suitable tool to improve malolactic fermentation outcome, and to contribute to wine aroma. The industrial-scale application of this strategy should be implemented to develop novel wine styles.
... Targeted analyses of fermentation-derived compounds (higher alcohols, acids, and esters) were performed by Metabolomics Australia (Adelaide) by GC-MS using a stable isotope dilution assay [48] at the end of fermentation, as well as 3 and 15 months post-bottling. ...
The higher alcohols 2-phenylethanol, tryptophol, and tyrosol are a group of yeast-derived compounds that have been shown to affect the aroma and flavour of fermented beverages. Five variants of the industrial wine strain AWRI796, previously isolated due to their elevated production of the ‘rose-like aroma’ compound 2-phenylethanol, were characterised during pilot-scale fermentation of a Chardonnay juice. We show that these variants not only increase the concentration of 2-phenylethanol but also modulate the formation of the higher alcohols tryptophol, tyrosol, and methionol, as well as other volatile sulfur compounds derived from methionine, highlighting the connections between yeast nitrogen and sulfur metabolism during fermentation. We also investigate the development of these compounds during wine storage, focusing on the sulfonation of tryptophol. Finally, the sensory properties of wines produced using these strains were quantified at two time points, unravelling differences produced by biologically modulating higher alcohols and the dynamic changes in wine flavour over aging.
... For example, tert-butanol, methyl ethyl ketone, and n-propanol have been used as internal standards for the determination of ethanol in blood (Boswell and Dorman 2015;O'Neal et al. 1996;Wasfi et al. 2004) and methanol, n-propanol, and tert-butanol have been used for analysis of consumer products (AOAC 2005(AOAC , 2017Ryapushkina et al. 2016). Deuterated internal standards are also commonly used when matrix effects are expected, although this requires MS detection due to coelution of the standard and target compounds (Siebert et al. 2005). ...
The method described herein can be used to determine the ethanol content in a variety of solid or semi-solid consumer goods (e.g., cakes, ice creams, sauces, powders) and can also be used for low-alcohol liquid products. It is based on mechanical homogenization and/or aqueous dilution of a product followed by static headspace analysis using gas chromatography with mass spectrometry (HS-GC–MS). A stable isotope internal standard in conjunction with an external standard calibration curve ensures that the method is both accurate and relatively insensitive to matrix effects. The linear range for the method covers 0.1 to 2% v/v (ABV) with a coefficient of determination (r²) ≥ 0.998. The limits of detection and quantitation are 0.003% v/v and 0.009% v/v, respectively. Reproducibility was < 4% RSD for each of two laboratory control samples. The average spike recovery across a variety of sample matrixes was 102 ± 10%, and a comparison with distillation followed by densitometry showed no statistical difference.
... Treatment description † from Siebert et al. (2005) and as described by Holt et al. (2013). Between 26 and 30 fermentation compounds were analysed with this method. ...
Background and Aims
Aeration during fermentation of red wines has the potential to enhance positive red fruit attributes and suppress less desirable reductive characteristics. The implementation of aeration in commercial winemaking, however, is impeded by the lack of a clear understanding of both the major benefits of its use and the nature of the aeration regimes required to modify the finished product. This work aimed to evaluate the impact of different modes of aeration, varying in their timing, duration and intensity, on fermentation duration, chemical composition and sensory properties of Shiraz wine.
Methods and Results
Forty‐eight pilot‐scale fermentations (450 kg) were treated with different aeration modalities and compared to non‐aerated fermentations across four vintages. This work demonstrated the reproducible effects of aeration, resulting in an enhancement of fruit‐related attributes, decreases in colour intensity and a lowering of astringent mouthfeel and bitterness. The development of attributes describing possible oxidation or undesirable volatility were not observed in this work. These effects on wine sensory attributes were correlated with an increase in the concentration of relevant short and branched‐chain esters and acetates, and a decrease in the concentration of phenolic substances. No enhancement of fermentation performance was observed in any of the trials. Overall, this work revealed the robustness of red wine fermentations to aeration.
Conclusions
This work provides strong evidence that aeration does not alter the duration of either alcoholic or malolactic fermentation of red musts. Although there was no impact on fermentation performance, aeration did result in the production of wines with increased red fruit characters, and decreased astringency and reductive off‐odours.
Significance of the Study
This work demonstrates aeration to be a useful oenological tool for the production of red wine and indicates that stylistic impact, rather than fermentation performance, is likely to be more pertinent to the adoption of red wine aeration.
... In this study, C 6 compounds were quantified with a SIDA method via SPME-GC/MS in SIM mode in 136 individual berries. Utilising SIDA methodology which employs the use of deuterium-labelled standards has been previously reported to overcome issues with the variability analogous to sample preparation as well as matrix effects resulting in a quantitative method with increased accuracy, precision and sensitivity for the determination of volatile compounds (Siebert et al. 2005, Maraval et al. 2010). The content of C 6 compounds on a per berry basis was plotted against berry TSS (Figure 3) to explore a possible relationship between the developmental stage (i.e. ...
Background and Aims
This study explored changes in the profile of selected aroma compounds in individual berries during development to establish whether a correlation exists between aroma compounds and sugar. Previous studies have assessed changes in the aroma compounds of ripening grapes using multiple berries randomly pooled together or sorted according to their diameter, density or colour. These data, while of value from a winemaking perspective, may prevent a fine interpretation of the compositional changes within individual berries characterised by asynchronous development.
Methods and Results
Individual berries of Vitis vinifera cv. Cabernet Sauvignon at different stages of development were sampled from veraison to harvest. Sugar concentration and mass of individual berries were measured, and C6 compounds analysed. The content of C6 compounds per berry was strongly correlated to the stage of development, while changes between stages were compound specific. Berries of similar TSS shared comparable composition of C6 compounds, with little influence of the sampling date.
Conclusions
Investigation of the composition of individual berries during ripening showed a strong dependency between the stage of development and the composition of sugar and C6 compounds.
Significance of the Study
Compositional changes of metabolites occurring in individual grape berries throughout ripening were identified. This study provides a starting point for a detailed study of the sugar/flavour nexus that may lead to an improved understanding of how to produce grapes with less sugar and more aroma, to overcome challenges associated with climate change.
... Volatile fermentation compounds, organic acids and 3-sulfanylhexan-1-ol. Nineteen esters and alcohols, and eight organic acids were measured in the finished Shiraz wines at T11 with large volume headspace/stable isotope dilution analysis (HS/SIDA)/GC/MS, by the Metabolomics Australia node at the AWRI as adapted from Siebert et al. (2005) and as described by Holt et al. (2013). The average concentration and SD of 26 volatile fermentation compounds [acetic acid (AcetAcid), butanoic acid (BuAcid), decanoic acid (DecAcid), hexanoic acid (HexAcid), 2-methylbutanoic acid (2-MeBuAcid), 3-methylbutanoic acid (3-MeBuAcid) octanoic acid (OctAcid), butanol (BuOH), hexanol (HexOH), 2-methylbutanol (2-MeBuOH), 3-methylbutanol Table S5. ...
Background and Aims
Winemakers utilise various remediation strategies for decreasing ‘reductive’ characters in wine. Remediation strategies, such as the addition of diammonium phosphate (DAP) during fermentation, copper fining, the addition of fresh lees or lees products to wine, and aeration of the must during and after fermentation, are commonly employed in an effort to prevent the formation or to remove undesirable volatile sulfur compounds. In this study, the relative effectiveness of five strategies for remediation of ‘reductive’ aroma was compared in a Shiraz wine.
Methods and Results
At the onset of the development of ‘reductive’ aromas during Shiraz fermentation, each ferment was treated with a unique remediation strategy: DAP addition; macro‐oxygenation; copper fining; a combination of macro‐oxygenation and copper fining; or the addition of fresh lees from a donor wine. While a relatively small difference in volatile sulfur compounds was found between treatments, copper fining, lees and DAP addition produced wines with elevated ‘reductive’ characters at certain time‐points post‐bottling; while macro‐oxygenation or macro‐oxygenation with copper produced wines with a low sensory score for ‘reduction’‐related attributes.
Conclusions
Macro‐oxygenation during fermentation was the most effective remediation strategy. Lees addition, and to a lesser extent, copper fining and DAP addition, diminished fruit attributes and produced wines with noticeable ‘reductive’ characters.
Significance of the Study
Macro‐oxygenation during fermentation produced wines with the lowest ‘reduction’‐related attributes while enhancing ‘fruity’ attributes. This work also highlighted the compositional effects of each type of remediation treatment.
... Yeast volatile fermentation products were analysed using stable isotope dilution analysis in conjunction with headspace solid-phase microextraction coupled with gas-chromatography mass spectrometry (GCMS) as described previously [16] and twenty-seven compounds, including ethyl and acetate esters, higher alcohols and volatile acids, were quantified. ...
Changes to Australian regulations now allow the limited addition of water to high-sugar musts pre-fermentation. In light of these changes, this study explored how water addition affects Shiraz wine composition and sensory properties. Wines were made from grapes at ≈13.5, 14.5 and 15.5° Baume. Water was added to musts from the ripest fruit by direct addition, or by using a juice substitution (run-off and replace) approach. To compare the effect of juice run-off independently, saigneé treatments were included. Wines made from the fruit that was harvested earlier generally had a lower “opacity” and higher “red fruit” aroma as the defining sensory attributes. Undiluted wines made from riper fruit had higher phenolics, and were characterised by “dark fruit” and “dried fruit” attributes, and “spice”, a “brown colour” and “opacity”. These attributes were accentuated in wines from the same fruit which received saigneé treatments and reduced in all of the water addition treatments. In particular, higher levels of water addition without juice substitution increased the “cooked vegetable” and “drain” attributes in the wines. This indicates possible negative effects of larger water additions, such that a low to moderate adjustment in Shiraz winemaking is suggested.
... A total of 28 fermentative compounds were analysed (in January 2020) by solid phase micro extraction (SPME)-GC-MS according to previously published method using Agilent Technologies Ltd. equipment (Melbourne, Australia) [16]. One mL of each sample was pipetted into 20 mL SPME vials with 9 mL of saturated potassium hydrogen tartrate buffer (pH 3.7) and 2 g of NaCl. ...
The aim of this preliminary study was to identify potential colour components, volatile and sensory attributes that could discriminate Pinot noir wines from five Australian winegrowing regions (Adelaide Hills, Yarra Valley, Mornington Peninsula, Northern and Southern Tasmania). The sensory analysis consisted of the Pivot© Profile method that was performed by wine professionals. A headspace solid-phase microextraction-gas chromatography-mass spectrometry method was used to quantify multiple volatile compounds, while the Modified Somers method was used for colour characterisation. Analysis of data suggested ethyl decanoate, ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, in addition to decanoic acid as important contributors to the discrimination between regions. Similarly, wine hue, chemical age indices, total anthocyanin, and (%) non-bleachable pigment also discriminated wines between regions. The sensory analysis showed that wines from Mornington Peninsula were associated with the ‘red fruits’ aroma, ‘acidic’, and ‘astringency’ palate descriptors, while those from Adelaide Hills were associated with the ‘brown’ colour attribute. This study indicates regionality is a strong driver of aroma typicity of wine.
... Further works are necessary to Data are presented as mean ± SD of duplicate analysis. Means followed by the same letters are not significantly different at the 0.05 level (Scott-Knott test) LRI linear intention index, NI LRI not identified, ND not detected a [37], b [38], c [30], d [39], e [40], f [41], g [42], h [43], i [19], j [44], k [45], l [46], m [47], n [48], o [35], p [49] Content courtesy of Springer Nature, terms of use apply. Rights reserved. ...
The sensory quality of fermented beverages, such as mead, is directly related to the raw material, microorganisms, and production process. The aim of this study was to evaluate the impact of Saccharomyces cerevisiae as single inoculum and co-inoculated with Meyerozyma caribbica on the physicochemical and sensory quality of mead. The meads were characterized according to their sugar, ethanol, furfural, hydroxymethylfurfural, ethyl carbamate, phenolics, volatile compounds, and sensory profile. Both starter cultures showed good fermentative capacity, resulting in beverages with 12% (w/v) alcohol content. 4-Methylumbelliferone and gallic acid were the most abundant phenolic compounds detected in both beverages. Ethyl carbamate was not detected; furfural detected below the quantification limit and 5-hydroxymethylfurfural was not higher than 0.3 mg/L. Among the identified volatile compounds, esters were the most abundant group. In general, unlike expected, the mixed inoculum resulted in a reduction of the volatile compounds. The mead produced with S. cerevisiae presented 1403.3 µg/L of esters and while mixed inoculum, 1084 µg/L. This result impacted the sensory analysis, in which the scores for flavor, aroma, and purchase intention were slightly higher for the mead produced with S. cerevisiae, although there was no statistical difference from the mixed inoculum. The results of this work indicate that further studies, such as on the adequacy of the must composition, are necessary for a better understanding of the potential of the used mixed inoculum.
... Glucose, fructose, glycerol and organic acids were determined (in duplicate) by high-performance liquid chromatography (HPLC), as described previously (Frayne, 1986), using an Agilent 1100 series HPLC (Agilent Technologies, Forest Hill, Vic., Australia), fitted with diode array and refractive index detectors. The concentrations of several fermentation volatiles (acids, alcohols and esters) were determined by Metabolomics Australia (AWRI) using gas chromatography-mass spectrometry (GC-MS), according to previously reported stable isotope dilution analysis (SIDA) methods (Siebert et al., 2005). ...
Worldwide, winemakers are increasingly adopting alcohol management strategies to counter the higher wine ethanol concentrations observed over the past ∼30 years. Wines with high ethanol levels exhibit increased ‘hotness’ on the palate, which is generally considered to negatively impact wine quality. This study investigated changes in the chemical and sensory profiles of five Cabernet Sauvignon wines following their partial dealcoholization by reverse osmosis-evaporative perstraction (RO-EP). Descriptive analysis (DA) of wine before and after RO-EP treatment indicated dealcoholization did not strongly affect wine aroma and flavor, consistent with the small changes observed in wine chemical composition. However, significant differences in the perception of wine palate attributes were observed, with dealcoholized wines found to exhibit lower acidity, sweetness, bitterness, saltiness and/or body. Astringency was enhanced following partial dealcoholization of one wine, but diminished in another. Sensory trials were also undertaken to determine the optimal ethanol concentration of wines, or the ‘alcohol sweetspot’. Two approaches to alcohol sweetspotting of dealcoholized wines were evaluated, together with two methods of statistical analysis, chi-squared goodness of fit and one proportion tests.
... The formula was as following: RCVS=(PAVC/ PAIS)×CIS, RCVC: relative concentration of volatile compounds; PAVC: peak area of volatile compounds; PAIS: peak area of internal standard; CIS: concentration of internal standard. Analysis was run in three samples and relative standard deviation between three replicates was determined [39][40][41][42]. ...
Vidal grape grown in Ili, Xinjiang Autonomous Region, is one of few grapes used to ferment ice wine in China. Microbial community structure and volatile composition during the spontaneous fermentation of ice wine made from Vidal grapes in Ili were investigated using amplicon sequencing technology and headspace solid-phase microextraction/gas chromatography-mass spectrometer technologies. Among bacterial genera, Sphingobium, Pseudomonas and Sphingomonas gradually decreased, while Lactobacillus and Streptococcus increased during the spontaneous fermentation process. As regards fungi, the relative abundance of Vishniacozymaand Cladosporium reduced, but Hanseniaspora sharply raised. Additionally, correlations between microbes and volatile compounds were constructed based on multivariate data analysis. The results revealed that the functional core microbiota (mainly composed of eight bacterial genera and nine fungal genera) during ice wine fermentation showed considerable correlations with the formation of twenty-four volatile compounds in ice wine made from Vidal grapes. For example, Saccharomyces was positively correlated with ethanol, ethyl acetate and isoamylol; Hanseniaspora and Candidawere negatively correlated with hexanol; and Lactobacillus and Streptococcus were positively correlated with 2,3-butanediol, ethanol, ethyl acetate, isoamylol and isoamyl acetate. This studyprovides a reference for understanding the process of ice wine fermentation and improving the quality of ice wine made from Vidal grapes.
... However, their compositional alteration caused by lactic acid bacteria during malolactic fermentation has not been well documented. In addition, volatile compounds have been confirmed to affect aromatic features of wine [28]. These grape-derived compounds determine the varietal aroma, and the fermentation and aging emphasize the fermentative and aging aromas of wine [29]. ...
Malolactic fermentation is a vital red wine-making process to enhance the sensory quality. The objective of this study is to elucidate the starter cultures’ role in modifying phenolic compounds, biogenic amines, and volatile compounds after red wine malolactic fermentation. We initiated the malolactic fermentation in Cabernet Gernishct wine by using two Oenococcus oeni and two Lactobacillus plantarum strains. Results showed that after malolactic fermentation, wines experienced a content decrease of total flavanols and total flavonols, accompanied by the accumulation of phenolic acids. The Lactobacillus plantarum strains, compared to Oenococcus oeni, exhibited a prevention against the accumulation of biogenic amines. The malolactic fermentation increased the total esters and modified the aromatic features compared to the unfermented wine. The Lactobacillus plantarum strains retained more aromas than the Oenococcus oeni strains did. Principal component analysis revealed that different strains could distinctly alter the wine characteristics being investigated in this study. These indicated that Lactobacillus plantarum could serve as a better alternative starter for conducting red wine malolactic fermentation.
... However, only 1-hexanol (3) and hexanal (11) remained in PPIs after AE-IEP (Fig. 1B). In addition, the concentration of 1-hexanol declined from part per million in pulse flours (Xu, Jin, & Lan et al., 2019) to part per billion in PPIs (Fig. S1), which resulted in the undetectable odor of 1-hexanol in PPIs as the olfactory threshold of hexanol is 4000 μg/L (Siebert et al., 2005)). Murat et al. (2013) reported that 135 μg/kg of 1-hexanol was detected in pea protein fraction; however, the odor of 1-hexanol was hardly caught by olfactometry. ...
In this study, pulse protein isolates (PPIs) were extracted from 0, 1, 3, and 5 days germinated chickpea, lentil, and yellow pea flours by alkaline extraction-isoelectric precipitation method. The germination time had negligible impact on the proximate composition of PPIs. In total, 67 volatiles in PPIs were identified via HS-SPME-GC-MS/O. Among all the identified volatile components, seven of them, including hexanal (11), (E)-2-octen-1-ol (7), (E,Z)-2,6-nonadienal (17), 3-octen-2-one (33), 3,5-octadien-2-one (34), 2-methoxy-3-isopropylpyrazine (56), and 2-methoxy-3-(1-methylpropyl)pyrazine (57), contributed to the beany-related odor of PPIs but much less than that in raw flours. However, the overall beany-related odor of PPIs increased when the germination time exceeded 1 day. Both the activity of lipoxygenase and the free radical populations in PPIs were positively related to the overall beany-related odor. Our findings are crucial for the preparation of germinated pulse proteins with improved functionality but without increasing undesirable odor.
... Cheese whey also has advantageous nutritional properties such as proteins with a high content of essential amino acids, especially branched-chain ones, high calcium content, and bioactive peptides (Haraguchi et al. 2006). Besides these beneficial characteristics of beetroot and cheese whey, the probiotic potential of Siebert et al. (2005) yeasts makes the produced beverages promising in the context of functional foods. ...
Purpose
This work aimed to assess the probiotic potential of different Kluyveromyces lactis strains isolated from Canastra cheese and to produce a fermented cheese whey beverage added to beetroot juice using the selected strain.
Methods
Kluyveromyces lactis strains were tested for their resistance to the passage through the simulated gastrointestinal tract, adhesion properties, and functional effects such as inhibition of enteric pathogens, short-chain fatty acids (SCFA) production, and β-galactosidase activity. The selected strain was used to produce a fermented cheese whey beverage added to beetroot juice in different proportions. The produced beverages were characterized using HPLC for sugars, Folin-Ciocalteu for total phenolic content, DPPH for antioxidant activity, and GC-MS for volatiles compounds.
Results
Except B51, all strains showed viability above 75% after exposure to the simulated gastric and duodenal juices. The aggregation rates were above 84% in 24 h. Only B9 and C16 strains presented hydrophobicity above 60%. The highest B9 β-galactosidase activities were 2.17 U/g and 2.21 U/g for pH 7 and 9, respectively. The B9 SCFA profile was similar to that found for Saccharomyces bourllardi. The fermented cheese whey beverages presented phenolic content ranging from 102.75 to 291.61 μg EAG/mL and inhibition of DPPH ranging from 38.69 to 81.02% after 21 days of storage, besides being lactose free. Esters and acetates were the most abundant compounds.
Conclusions
Kluyveromyces lactis B9 presented interesting results as a potential probiotic yeast. The produced beverages allowed the delivery of K. lactis B9 through innovative product with functional properties.
Among the family of sugarcane spirits, those made from juice are diverse and often produced in a traditional way. They must be distinguished from other sugarcane spirits, which are more widely produced and made from other sugarcane derivatives, such as molasses. These alcoholic beverages contribute significantly to the socio-economic development of many countries. However, despite ancestral know-how, there is a lack of contemporary data required to characterize some sugarcane juice spirits (SCJSs) and to overcome the current and future threats that producers will have to face. While preserving their authenticity and specificity, SCJS producers expect to improve and ensure sufficient yield and a superior quality product. Even if the scientific knowledge on these spirits is not comparable, the available data could help identify the critical points to be improved in the making process. This review aims to present the main SCJSs encountered worldwide, defining their specific features through some important aspects with, notably, references to the complex notion of terroir. To continue, we discuss the main steps of the SCJS process from harvesting to aging. Finally, we expose an inventory of SCJS’s chemical compositions and of their sensory description that define the specific organoleptic properties of these spirits.
Fungal infection of grape berries (Vitis vinifera) by Botrytis cinerea frequently coincides with harvest, impacting both the yield and quality of grape and wine products. A rapid and non-destructive method for identifying B. cinerea infection in grapes at an early stage prior to harvest is critical to manage loss. In this study, zeolitic imidazolate framework-8 (ZIF-8) crystal was applied as an absorbent material for volatile extraction from B. cinerea infected and healthy grapes in a vineyard, followed by thermal desorption gas chromatography-mass spectrometry. The performance of ZIF-8 in regard to absorbing and trapping the targeted volatiles was evaluated with a standard solution of compounds and with a whole bunch of grapes enclosed in a glass container to maintain standard sampling conditions. The results from the sampling methods were then correlated to B. cinerea infection in grapes, as measured and determined by genus-specific antigen quantification. Trace levels of targeted compounds reported as markers of grape B. cinerea infection were successfully detected with in-field sampling. The peak area counts for volatiles 3-octanone, 1-octen-3-one, 3-octanol, and 1-octen-3-ol extracted using ZIF-8 were significantly higher than values achieved using Tenax®-TA from field testing and demonstrated good correlation with B. cinerea infection severities determined by B. cinerea antigen detection.
Preliminary research was conducted on the analytical and flavor profiles of beers brewed (small-scale) with roasted specialty malts and raw malts as adjuncts. Beers were characterized by physico-chemical, sensory, and GC-MS analysis. From the beers produced, 79 volatile compounds were identified, and these were grouped into different categories. Alcohols and esters were found to be the most prevalent volatile compounds in the beers. Principal component analysis, as well as cluster analysis, was applied in order to investigate the similarities and distinctions between the various types of adjuncts and no adjunct beers. The volatile chemicals present in the beers showed that the nature and quantity of these compounds would have an effect on the flavor and quality of the beers. Beers prepared with the roasted wheat malt addition were characterized by the highest number of volatile compounds. Moreover, the beers with roasted wheat malt addition were characterized by higher bitterness (higher than the control beer), high antioxidant activity (equal to the control beer), and a high tannin content (but less than the control beer). Beers were evaluated by a sensory panel that concluded that the adjunct beers had a preferred flavor to the beers without adjunct addition. The highest-rated beer in the appearance, flavor, mouthfeel, and overall acceptability criteria was the adjunct beer with roasted wheat malt incorporated. This preliminary experimentation will help guide where future research is needed and where scale-up experiments with trained taste panels should focus.
The major off-flavor odorants of normal (NOR) and lipoxygenase-lacking (LOX-lack) soy protein isolates (SPIs) were discriminated by sensory-directed flavor analysis. A total of 32 odor-active off-flavor compounds were detected in SPIs, and 19 of them with flavor dilution (FD) factors ranging from 3 to 2187 were quantified by external standard curves. It was found that hexanal and nonanal dominated in the off-flavor profile of SPIs regarding their odor activity values (OAVs) and FD contributions, followed by octanal, 1-hexanol, 1-octen-3-ol, 2-heptone, and benzaldehyde. To further improve the precision of quantification, the above 7 major odor-active off-flavor compounds were requantified by stable isotope dilution assays (SIDA) for the first time. The results suggested that the sensory differences between NOR and LOX-lack SPIs could be mainly due to the reduced C6/C9 aldehydes and alcohols rather than 1-octen-3-ol and benzaldehyde. Finally, these differential compounds were further verified by the spiking experiment.
Wine is highly appreciated for its distinctive sensory characteristics, including its colour,
aroma, and taste. However, unwanted microbiological activity, unbalanced concentrations of certain
compounds resulting from unbalanced grape chemical compositions, and inadequate winemaking
practices and storage conditions can result in sensory defects that significantly decrease wine
quality. Although preventing wine defects is the best strategy, they are sometimes difficult to avoid.
Therefore, when present, several fining agents or additives and technologies are available or being
developed with different performances regarding their impact on wine quality. Wine stabilisation
refers to removal and prevention strategies and treatments that limit visual, olfactory, gustatory, or
tactile wine defects, as well as increase wine safety and stability through fining and the application
of different operations carried out in wineries (filtration, pasteurisation, electrodialysis, and cold
stabilisation) and the use of emerging technologies (electron-beam irradiation, high hydrostatic
pressure, pulsed electric fields, ultrasound, pulsed light). Future trends in this field involve using
more sustainable and environmentally friendly fining agents and technologies and developing
treatments with better performance and specificity.
This Book of the Special Issue focuses on different aspects of wine sensory faults, their origin,
prevention, and removal, and their impact on wine sensory quality. This Special Issue, composed of
ten valuable accepted and published articles, divided into seven original articles and three reviews,
provides an overview of the main wine sensory faults describing their origin, prevention, and
removal strategies. Topics include origins of wine sensory faults, the impact of the wine faults on
wine quality and safety, prevention of wine faults either by viticultural or oenological practices,
the performance of available fining agents and new potential fining agents for the removal of wine
defects, their selectivity, and impact on wine quality, methods to estimate wine stability. The Special
Issue collected contributions from researchers from Universities and Research Centres from different
parts of the world, namely Italy, Spain, Portugal, Moldova, North Macedonia, Slovakia, Canada, the
USA, Australia, and China, establishing the interest of the international scientific community toward
the aims mentioned above and scopes.
Briefly, Ailer, Jakabova, Benesova, and Ivanova-Petropulos, reviewed the latest scientific findings ´
and recommendations for the prevention of the reductive aromas, mainly caused by excessive
H2S and other volatile sulphur compounds, of browning associated with the enzymatic and
non-enzymatic catalysed oxidation of polyphenols, and atypical ageing, associated with the stress
and lack of nutrients and moisture in green land cover in the vineyard. In the original contribution
from Errichiello, Picariello, Guerriero, Moio, Forina, and Gambuti, the management of the dissolved
oxygen content in wines by a polypropylene hollow fibre membrane contactor apparatus was
performed. After ageing (11 months), red wines with high oxygen content resulted in the massive
formation of polymeric pigments and BSA reactive tannins, as opposed to wines with low oxygen
levels, demonstrating that the membrane contactor can be a successful tool to manage dissolved
oxygen in wines as to prevent their oxidative spoilage. Celotti, Lazaridis, Figelj, Scutaru, and
Natolino, evaluated the use of a portable prototype instrument for light irradiations at different
wavelengths and times to evaluate the oxidative stability of white wines and the effect of some
oenological adjuvants on wine stability. The sensorial analysis revealed that white and light blue
were the most significant after only 1 h of irradiation. The experimental results showed that
hydrogen peroxide could enhance the effect of light treatment. On the other hand, light exposure
ix
of white wine can cause a light-struck taste, a fault induced by riboflavin and methionine activation
leading to the formation of volatile sulphur compounds (VSCs), including methanethiol (MeSH) and
dimethyl disulphide (DMDS). Fracasseti, Limbo, Messina, Pellegrino, and Tirelli, studied the impact
of different antioxidants, i.e., sulphur dioxide (SO2), glutathione (GSH), and chestnut tannins (CT),
either individually or in various combinations, on preventing light-struck taste (LST). The presence
of antioxidants limited the formation of light-struck taste as lower concentrations of volatile sulphur
compounds. The order of their effectiveness was CT ě GSH >SO2. The results indicate tannins as an
effective oenological tool for preventing LST in white wine.
Morata, Loira, Gonzalez, and Escott reviewed the use of non-Saccharomyces yeasts, such as ´
Lachancea thermotolerans, which results in effective acidification through the production of lactic
acid from sugars and yeasts with hydroxycinnamate decarboxylase (HCDC) activity can be helpful
to promote the fermentative formation of stable vinylphenolic pyranoanthocyanins, reducing the
amount of ethylphenol precursors that can be used as natural solutions for preventing the formation
of undesirable off-flavours in wines.
Pickering and Botezatu reviewed a range of vineyard practices that seek to reduce
Coccinellidae densities, as well as both “standard” and novel wine treatments aimed at reducing
alkyl-methoxypyrazine load responsible for the recently recognised faults known as Ladybug taint
possessing excessively green, bell pepper-, and peanut-like aroma and flavour.
In their original contribution, Xiao, Li, Chem, Li, Quan, Zhang, King, and Dai studied the
effect of triazole pesticides that are widely used to control grapevine diseases. However, they can
significantly affect the ester and acid aroma components and change the wines’ flower and fruit
flavour. This change was attributed to changes in the yeast fermentation activity caused by the
pesticide residues. underlining the desirability of stricter control by the food industry over pesticide
residues in winemaking.
Rinaldi, Gonzalez, Moio, and Gambuti investigate using three different commercial
mannoprotein-rich yeast extracts (MP, MS, and MF) to reduce high bitterness and astringency in
finished wines resulting from pressing marcs and extended maceration techniques that increase the
extraction of phenolic compounds. Mannoproteins had a different effect depending on the wine’s
anthocyanin/tannin (A/T) ratio. When tannins are strongly present (extended maceration wines
with A/T = 0.2), the MP conferred mouthcoating and soft and velvety sensations and colour stability
to the wine. At A/T = 0.3, as in marc-pressed wines, both MF and MP improved the mouthfeel and
colour. However, in free-run wine, where the A/T ratio is 0.5, the formation of polymeric pigments
was allowed by all treatments and correlated with silk, velvet, and mouthcoating subqualities.
The selection of variants of AWRI796 yeast strains can be used to modulate the formation of
higher alcohols 2-phenylethanol, tryptophol, and tyrosol and methionol, as well as other volatile
sulphur compounds derived from methionine, highlighting the connections between yeast nitrogen
and sulphur metabolism during fermentation, and modulate the dynamic changes in wine flavour
over ageing (Cordente, Nandorfy, Solomon, Schulkin, Kolouchova, Francis, and Schmidt).
Cork powder after extractives removal and air removal by ethanol impregnation was studied in
its efficiency in removing 2,4,6-Trichloroanisole (TCA) from contaminated red wines. This potential
fining agent removed 91% of TCA from wines containing 6 ng/L of TCA at an optimised cork powder
application of 0,25g/L. The impact on wine colour, phenolic composition and volatile compounds
was low, making this modified cork powder a potential and sustainable fining agent to cope with this
fault (Cosme, Gomes, Vilela, Filipe-Ribeiro, and Nunes).
x
As a final note, the Guest Editors would like sincerely to thank all the authors for selecting this
Special Issue to publish the results of their hard research work or reviews, as well as to the reviewers
and the assistant editors for their precious support, that will contribute to the success of these Special
Issue and Book.
Fernando M. Nunes, Fernanda Cosme, and Lu´ıs Filipe-Ribeiro
Editors
Background and Aims
Whole bunch fermentation is widely used in red wine production but research on whole bunch fermentation is limited, especially for cool climate Pinot Noir. Inclusion of whole bunches or grape stems was investigated in Pinot Noir wine production with respect to extraction of phenolic compounds and aroma production.
Methods and Results
Five Pinot Noir wines were microvinified by including grape stems or whole bunches at various levels: destemmed grapes (DS), 100% stems added back (DS100), 30% whole bunches (WB30), 60% whole bunches (WB60) and 100% whole bunches (WB100). The DS100, WB60 and WB100 treatments showed significantly increased tannin and monomeric phenolics but decreased anthocyanin in wines, which would consequently influence the mouthfeel and colour of wine. Volatile compounds responsible for green/vegetative, spicy, woody and medicinal aromas, including 3-isobutyl-2-methoxypyrazine, 3-isopropyl-2-methoxypyrazine, eugenol, ethyl cinnamate and phenol, were significantly increased in DS100, WB60 and WB100 treatments. The WB30 treatment did not show a significant increase of methoxypyrazines in the resultant wine.
Conclusions
By adding stems or a high proportion of whole bunches in fermentation, increased extraction of tannins may improve the mouthfeel and structure of Pinot Noir wine, but the significantly increased concentration of methoxypyrazines could negatively affect wine quality due to the enhanced green characteristics.
Significance of the Study
This study reveals the significant impact of stem inclusion during fermentation on phenolic and aroma compounds in Pinot Noir wine, which provides insights into better use of whole bunches and stems to improve Pinot Noir wine quality.
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.
Fruit beer, a recognized special beer, is produced with fruit addition during fermentation, maturation, or the refermentation process. Volatile organic compounds of seven fruit beers were investigated using a gas chromatography-ion mobility spectrometry (GC-IMS) technique. A total of 38 compounds were identified, and volatiles in the seven beers differed greatly. The concentration of nonanal, methyl octanoate, ethyl 2-methylbutanoate, propyl hexanoate, and methyl 2-methylbutanoate was high, and the first two compounds were the characteristic volatiles in the pineapple beer. Apple beer had a higher concentration of butyl acetate, isobutyl acetate, methyl heptanoate, and butanal. Butyl acetate was the specific apple beer volatile. Peach beer showed a higher concentration of 3-methylbutanal, methional, phenylacetaldehyde, α-pinene as well as 2,3-diethyl 5-methylpyrazine, and the last was detected only in the peach beer. Ethyl heptanoate and maltol were abundant in the cranberry beer, whereas linalool, furaneol, and benzaldehyde were rich in the cherry beer, and benzaldehyde was the characteristic cherry beer volatile. Raspberry beer had abundant 3-pentanone, ethyl propanoate, and E-2-hexenol, whereas blueberry beer had abundant ethyl 2-hydroxypropanoate. Discrimination and classification of the seven fruit beers were effectively performed by the principal component analysis (PCA) method with good dispersion, and all groups had corresponding attribution areas in the PCA map. The cumulative contribution rate of the first two PCs was 60%. This study offers an approach for the analysis of the volatiles of fruit beers and could help in the verification of adulteration in fruit beers.
Gas chromatography (GC) has been used for the analysis of wine almost since its inception. While the focus of much research (both initially and currently) has been the application of GC for the analysis of volatiles associated with aroma, many other analytes can be measured by GC, including pesticides, sugars, acids, amines, polyphenols, and organic metal-containing compounds (e.g., organic selenium). This review will discuss selected current applications of GC for analysis of wines, while emphasizing future trends and challenges and providing an update since the first edition of this volume.
Background and Aims
The presence of matter other than grapes (MOG) is common in the winemaking process when sorting equipment is not utilised. Experimental wines were made to examine the effect of MOG on the sensory profile and chemical composition of wine.
Methods and Results
A Shiraz wine made without MOG was compared to fermentations with grape leaves, grape stalks (rachis) and peduncles (the stalk connecting the bunch to the vine) added at amounts at or slightly above those found in a commercial harvest bin. Fifty‐one volatile aroma compounds were quantified in the wines, and sensory descriptive analysis was applied. The wine made with leaves added was rated by the sensory panel similar to the Control and was significantly higher only in positive aromas such as ‘confectionery’ and ‘red fruit’ likely due to a higher concentration of hexanol and (Z)‐3‐hexen‐1‐ol. The addition of peduncles slightly enhanced ‘green’ aroma and flavour. The rachis treatment was high in ‘green capsicum/green stalks’ attributes, as well as astringency, and was high in methoxypyrazines.
Conclusions
The inclusion of different types of MOG during fermentation can alter the sensory profile and chemical composition of Shiraz wines in varying ways, including extraction of methoxypyrazines from the rachis, resulting in notable ‘green’ attributes.
Significance of the Study
The inclusion of MOG is unavoidable in common winemaking practices, especially with the use of mechanical harvesting. Determining the influence of MOG on the volatile composition of the finished wine is an important step in manipulating wine style.
The study on fermentation kinetics of the coconut inflorescence sap is important to
understand its shelf life at different storage conditions and to develop suitable value-added products. The coconut inflorescence sap collected by using an in-house developed coco-sap chiller device is called Kalparasa. The fermentation characteristics of Kalparasa were investigated at every one-hour interval under ambient (31±2 oC) and refrigerated (5±1 oC) storage conditions.The results reveal that pH of the sap and total sugar content decline rapidly under ambient conditions than under refrigerated conditions. Acidity, turbidity, and reducing sugar content significantly (p<0.001) increases for the sap stored under ambient conditions. The reaction rate constant (k) of the vitamin C and total sugar degradation increases with the atmospheric fermentation. The degradation kinetics of vitamin C and total sugar in Kalparasa during natural fermentation (ambient condition) follow second-order equation whereas the reducing sugar follows the first-order equation
“Geographical Indication (GI) Hokkaido” has been operating since 2018 with the aim of ensuring the quality and branding of wine produced in Hokkaido. The amount of volatile acid, mostly acetic acid, should be regulated for GI certification since excessive amounts contribute to objectionable off-flavors of wine. In this study, a new application of gas chromatography (GC) followed by ethyl acetate extraction was examined as a simple and reliable method of measuring acetic acid in wine. Higher reproducibility (RSD: 2.1 % to 4.4 %) was observed in three types of wine samples with different acetic acid concentrations (254 to 756 µg/mL), accompanied by satisfactory recoveries (98 % to 102 %). The determination range was 254 to 1 236 µg/mL, well covering the required criterion (＜1 000 µg/mL). Significant correlations were recognized between the GC method and high-performance liquid chromatography (HPLC), which has been approved as a screening method for measuring volatile acid in GI wine (r＝0.993, p＜0.0001, n＝22), and also the distilled-titration method (r＝0.974, p＜0.0001, n＝19). Thus, the proposed GC method for the determination of acetic acid in wine samples is simple and reliable; furthermore, it will be useful as an alternative reference based on a different principle to the traditional titration method or the prevalent HPLC method.
Vitis vinifera L. Pinot noir still wines are some of the most popular and expensive red wines in the world. Several research articles are reported in literature concerning the impacts of viticultural and enological practices, and vineyard location, on Pinot noir still wine aroma. This review summarizes the previous and latest literature pertaining to volatile compounds including esters, higher alcohols and C 13-norisoprenoids, and their effect on Pinot noir wine perceived aroma. Their origin and behavior are discussed, as well as their role in regional differentiation. The first part of this review paper presents an overview of volatile compounds that are usually found in Pinot noir still wines at concentrations higher than their odor detection threshold. The second part deals with studies pertaining to human inputs that impact on Pinot noir wine aroma profile such as viticulture and winemaking interventions. The role of the vineyard site is also revised. This review concludes by considering what further opportunities are available to researchers in this field for greater control over Pinot noir wine quality outcomes.
Aureobasidium pullulans has been observed as one of the most abundant species in freshly pressed grape juice. Despite this, little is known about the consequences for the wine-making process associated with the presence and proliferation of this fungus, including its interaction with other ferment-derived microorganisms and impact on the composition of the resulting wine.
In this study, the physiology of abundant A. pullulans grape juice isolates was investigated through lab scale fermentation trials, demonstrating the ability of this species to survive in grape juice while producing polysaccharides, polymers of malic acid (poly β-malic acid) and enzymes with pectinase, β - glucosidase and tannase activity. A possible antagonistic effect against yeast through competition for metals including Fe and Zn was also observed. Overall, the data suggests this abundant species could have important implications for wine production and quality.
In recent years, hop aroma emerged as a key quality characteristic of popular beer styles. Accordingly, the instrumental analysis of hop derived odorants in beer advanced as a must have analytical technique for research and quality control purposes. Still, the analysis of hop aroma compounds is challenging. Substance concentrations might strongly vary depending on the beer style, matrix effects might hinder reliable quantification, and SPME-GC-MS based protocols are suspected to lack (long-term) stability. The current paper describes the validation and application of a headspace solid-phase microextraction (HS-SPME) – gas chromatography (GC) – tandem mass spectrometry (MS/MS) method for analysis of 16 selected hop aroma compounds in beer. To enable rapid and reliable quantification of selected terpenes, terpenoids, and esters across a wide working range (1–1000 µg/L), instrumental parameters were optimized and three stable isotope labeled standards, namely d5-linalool, d2-myrcene, and d6-citronellol were synthesized and characterized by nuclear magnetic resonance (NMR) spectroscopy. Extensive method validation and routine application proves the excellent selectivity, sensitivity, and robustness of the method in all relevant matrices such as light hopped lagers and dry-hopped ales.
Headspace solid phase micro extraction (HS–SPME) was used for extraction of aroma compounds characterizing a Piedmont wine (Ruché) derived from a non aromatic vine. Extracted compounds were identified by ion trap mass spectrometry (ITMS) after gas-chromatographic analysis. In this way a selection of 59 identified primary aromatic compounds, related to the typical flavour of Ruché was made possible. The SPME technique showed peculiar behaviour in that 23 of the 59 compounds identified were not detected by liquid-liquid solvent extraction of the same samples. Subsequent comparison with the aromatic profiles of different wine samples obtained by microvinification from different grape varieties showed similarities between Ruché and the wines, Brachetto and Malvasia, originating from aromatic vines. SPME analysis proved to be useful in understanding aroma compositions of all samples examined, establishing bases for further investigations on the chemical and biochemical mechanisms underlying wine aroma development.
Different headspace solid-phase microextraction (HS-SPME) methods have been selected and applied to the analysis of volatile compounds in ‘fino’ sherry wine by gas chromatography-mass spectrometry. A method based on rotary and continuous liquid–liquid extraction (LLE) for analysis of these same compounds has been optimised. The best conditions to extract this type of compounds using SPME and LLE were determined and both methods were validated. Both methodologies show adequate detection and quantitation limits, and linear ranges for correctly analysing these compounds. The recoveries obtained were close to 100%, with good repeatability values. The analytical and procedural advantages and disadvantages of these two methods have been compared. In general, SPME presented higher sensitivities. Both analytical methods were used to analyse five samples of ‘fino’ sherry wine supplied by different producers. No significant differences were found between the techniques at a significance level of 5%. The regression coefficients (r2) for analysis using LLE and SPME exceeded 0.94 for all compounds. The LLE procedure is a method with high repeatability and has the possibility of simultaneous extraction of several samples (up to 12), however the SPME technique is a solvent-free method presenting major advantages, such as small sample volume and higher sensitivity and simplicity.
A mixture of [(2)H(7)]-geraniol, [(2)H(7)]-nerol, [(2)H(7)]-linalool and [(2)H(7)]-alpha-terpineol was prepared for use as internal standards in a rapid and accurate analytical method, employing gas chromatography-mass spectrometry (GC/MS), to determine the concentration of geraniol, nerol, linalool and alpha-terpineol in wine. The method avoids the possible formation, degradation and interconversion of these compounds during their analysis.
Stir bar sorptive extraction (SBSE) coupled with gas chromatography/mass spectrometry (GC/MS) was used to analyse wine samples for three applications: flavour and compositional analysis; 2,4,6-trichloroanisole (TCA), a common off-aroma in wine; and agrochemicals. SBSE was found to be orders of magnitude more sensitive than modern conventional methodology, allowing for lower detection and quantitation levels, and improved confirmation of identity; SBSE often gave better signal to noise in scan mode than other methods in selective ion monitoring (SIM) mode. With the help of their characteristic mass spectra all agrochemicals could be identified unambiguously at concentrations of 10 microg L(-1) in wine and a further 100 constituents were detected in a Cabernet Sauvignon sample. Thus it is now possible to analyse complex samples such as wine by scan mode, with better confirmation of identity, and without sacrificing sensitivity, where previously SIM methodology had to be used.
Fifty‐two young monovarietal red wines made with Grenache (17 samples), Tempranillo (11 samples), Cabernet Sauvignon (12 samples) and Merlot (12 samples) grapes have been analysed by HRGC–MS to obtain quantitative data on 47 odorants previously identified as potential aroma contributors by olfactometric techniques. Thirty‐three odorants were present in the wines at concentrations higher than their corresponding odour thresholds. These include ethyl octanoate, β‐damascenone, ethyl hexanoate, isovaleric acid and isoamyl acetate as the most important, which together with isoamyl and β‐phenylethyl alcohols, fatty acids, 2,3‐butanedione and ethyl butyrate are always found at concentrations higher than their odour thresholds. In some cases the ethyl esters of isobutyric and isovaleric acids, β‐ionone, methionol, isobutyric acid, ethyl cinnamate, ethyl dihydrocinnamate, γ‐nonalactone, eugenol, c‐3‐hexanol, geraniol, guaiacol, 3‐isobutyl‐2‐methoxypyrazine, 4‐ethylguaiacol, acetoin and t‐whiskylactone were at a concentration high enough to be odour‐active. There were 30 compounds that were found to differ significantly between varieties. These include 3‐isobutyl‐2‐methoxypyrazine, isoamyl acetate, isovaleric acid, ethyl isobutyrate, ethyl isovalerate, fusel alcohols, c‐3‐hexenol, methionol, eugenol, guaiacol and γ‐nonalactone.
© 2000 Society of Chemical Industry
The purpose of this work was to determine the influence of variety, clarification type, fermentation temperature, and the addition of selected yeast on wines to obtain dry wines from grape must of Muscatel and Malvasia varieties. An experimental design was tried, based on 74 white wine samples identified through 19 analytical variables and submitted to analysis of variance (ANOVA), multivariate analysis of variance (MANOVA), and principal component analysis (PCA). The study is carried out with two varieties of white Vitis vinifera grapes (Muscatel and Malvasia) which are used in the production of Spanish white wine. The must was clarified following two different procedures (static decantation and membrane filtration) and later fermented at laboratory scale at three temperatures (15°C, 18°C, and 21°C) and two yeast types (D47 and K1M) were inoculated into the must. Significant differences were found according to grape variety, clarification, temperature, and yeast type when ANOVA and MANOVA were performed. The application of PCA to the data showed that differences between organic acids and higher alcohols are mainly due to the grape variety and the yeast type used for fermentations. With the results found, we propose the best conditions to obtain dry wines from Muscatel and Malvasia varieties.
A study was conducted of the dynamics of Saccharomyces and non-Saccharomyces populations during alcoholic fermentation of Albarino musts from two enological subzones located in Galicia (Northwest Spain). Sixteen microvinifications were carried out (8 in each must, M and E) with five indigenous Saccharomyces cerevisiae strains, two commercial active dry strains, and the corresponding spontaneous fermentation. The volatile compounds in the resulting wines were measured using gas chromatography. The study of different physiological and biochemical characteristics allowed us to follow the evolution of the inoculated S. cerevisiae strains. The different cellular concentrations of these strains in the musts produced different growth rates during fermentation. The growth of non-Saccharomyces flora depended on the initial starter culture concentrations and on their growth rate during winemaking. Statistical analysis (factorial and cluster) of data obtained by gas chromatography created statistical relationships between the production of some components of wine aroma and the evolution of yeast flora during alcoholic fermentation.
Pyridine alkaloids in tobacco (Nicotiana tabacum L.) and tobacco smoke are widely recognized for their contributions to tobacco quality and usability (Palmer 1963; Tso 1990). Nicotine is the most abundant alkaloid and may provide a pleasurable alerting effect associated with tobacco uses. The neurobiology of nicotine has been reviewed by Ashton et al. (1979). Health risks of tobacco alkaloids have also been summarized (Davis 1987). Nitrosated alkaloids may be carcinogenic (Hoffmann et al. 1987). Sums of alkaloids other than nicotine are generally small but may range up to 20% of total alkaloids (Andersen et al. 1991). Most alkaloids identified in postharvest burley and dark tobaccos or products containing them are given in Table 1. All of these compounds may be referred to as alkaloids because they occur naturally in green or processed tobacco, or they can be classified as “parent” alkaloids and their acylated, nitrosated, or oxidized derivatives. Structures of six representative tobacco alkaloids are shown in Fig. 1.
Phenolic and volatile compounds play an important role in enology owing to their contribution to wine sensory properties and to their participation in various phenomena during winemaking and aging process. The objective of this work was to establish the relationship between the phenolic and volatile composition and the type of winemaking technologies. Four Castelão (Vitis vinifera, cv.) red wines were made by different winemaking technologies: carbonic maceration (maceration temperature 35 °C and maceration time 21 days), stem-contact fermentation (maceration time 7 and 21 days) and non stem-contact fermentation (maceration time 7 days). Phenolic compounds were analyzed by liquid chromatography (LC) and spectrophotometric methods. The volatile composition was analyzed by HRGC and by gas chromatography–mass spectrometry (GC–MS). Multivariate analysis, i.e., clustering and principal component analysis (PCA), was applied to the results of phenolic and volatile composition. The carbonic maceration wine had less color intensity, lower concentrations of phenolic compounds and of 1-hexanol, 2-phenylethanol, diethyl succinate, and diethyl malate, but higher concentrations of benzyl alcohol and ethyl lactate than the skin fermentation wines. Stems are an important source of polyphenols, but increasing maceration time decreased both total and some individual anthocyanins. The volatile composition was not significantly affected by the presence of stems. Phenolic and volatile composition appeared a powerful tool to distinguish the wines made by different winemaking technologies, particularly to distinguish the carbonic maceration wine from the skin fermentation wines.
It has been shown that the proportion of fatty acid ethyl esters retained by the yeast cell increases with increasing acyl chain length as the ester becomes more lipid soluble. The distribution of esters depends on the yeast strain and on the fermentation temperature; larger amounts of esters were found to transfer from the cells into the medium at higher temperature. It was shown that esterase activity is located both inside and outside the yeast cell plasma membrane. Intact yeast was capable of hydrolysing the ethyl esters of caproic, caprylic and capric acid. Acetate esters, were hydrolysed only very slowly or not at all. The hydrolytic activity of baker's yeast was studied with ethyl caprylate as substrate. The hydrolysis was very fast at the beginning. The equilibrium attained depended not only on the concentration of ester and alcohol but also on the pH, a higher amount of ester remaining in solutions of lower pH. It was also shown that the esterases possess appreciable ester synthesizing ability and an equilibrium was attained by incubating yeast with caprylic acid and ethanol. The experiments described show that the ester level in an alcoholic beverage, such as beer, is not dependent solely on the ester concentration formed during fermentation: in the presence of yeast the level can be shifted in either direction by changing temperature, pH or alcohol concentration — or the amount and type of yeast.
The yeast plasma membrane regulates the movement of compounds into the yeast cell and of yeast metabolites from the cell into the medium. The rate of penetration of organic acids into the yeast cell depends on their lipophilic nature, and on their molecular size and degree of branching. During fermentation yeast synthesizes a vast number of aroma compounds. The numerically and quantitatively largest groups of aroma compounds include fusel alcohols, fatty acids and fatty acid esters. The yeast used and the fermentation conditions can influence the formation of aroma compounds. The yeast also has a profound effect on the formation of other aroma compounds, such as sulphur compounds and phenols. In addition to fermentation, the maturing of a beverage can also influence the aroma. During the maturing lactones, phenols and other compounds are extracted from the oak casks in which the beverage is aged. The presence of the so-called “whisky lactone”, β-methyl-γ-octalactone, is characteristic of a beverage that has been matured in oak.
The most famous wine type of Hungary is Tokaji Aszú. Noble rotted botrytised (Aszú) grape berries and a specific vinification technology give its unique delicious aroma and taste. The present work compares volatile aroma components of noble rotted Aszú grape berries from two different locations in the Tokaj wine district. Aszú grape berries have been soaked in 10% ethanol-containing water solutions and thereafter extracted with Freon 11. Volatile components were determined by gas chromatography-mass spectrometry (GC-MS). The total ion chromatograms contained 220–260 components. More than 80 components are identified, among them alcohols, aldehydes, acids, acetals, esters, epoxides, nitrils, furan derivatives and lactones. The compositional differences between the two Aszú grape samples are analysed according to the different component classes. The differences are quantitative rather than qualitative. Some δ-lactones are identified for the first time in noble rotted berries from Tokaj. These substances have very characteristic odor notes such as coconut, chocolate, peach, fruity. Together with the identified γ-lactones they seem to be characteristic aroma components of Tokaji Aszú wines.
The application of solid-phase microextraction (SPME) far flavor analysis has been studied. SPME headspace and liquid sampling were tested for 25 common flavor components in dilute aqueous solution. The addition of salt generally enhances SPME adsorption. Larger sample volume and a smaller volume of headspace over the liquid sample also increase the sensitivity of SPME-based analysis. For thermal desorption following SPME, a GC injector liner with small diameter, e.g., 1 mm i.d., improves resolution and obviates the need for cryogenic focusing. The SPME technique was applied to authentic samples: ground coffee, a fruit juice beverage, and a butter flavor in vegetable oil. The advantages and limitations of SPME are discussed.
Symphony grapes were fermented with 20 different strains of the yeast Saccharomyces cerevisiae (Sonoma Native, Fermirouge, A96, S6U, L2056, A350, Fermicryo, RA17, Steinberg, D254, Fermiblanc, T73, St George, CX3079, Pdm, MI16, VL1, LY3079, A350/VL1/Fermiblanc, and BM45). Among 53 volatile compounds identified in the wines using gas chromatography/mass spectrometry, the major volatile compounds found were seven alcohols, seven esters, and four acids. Isoamyl alcohol was the compound found in highest amounts with 19 yeast strains of Symphony wines. The amounts of isoamyl alcohol ranged from 6.04mg/l (A350/VL1/Fermiblanc) to 14.33mg/l (Fermirouge). The other major compounds were 2-phenyl ethanol, ethyl-2-hydroxy propionate, monoethyl succinate, octanoic acid, and hexanoic acid. Several esters, including ethyl-2-hydroxy propionate, may contribute to the fruity flavor of Symphony wines. Overall, 18 S. cerevisiae yeast strains (except A350/VL1/Fermiblanc and T73) used to ferment Symphony grapes produced the same major components, with certain variations in formation levels. The formation and composition of the volatiles produced by A350/VL1/Fermiblanc and T73 yeast strains were significantly different from the other strains. The different S. cerevisiae yeast strains contributed to the characteristic flavors in Symphony wines.
Headspace solid-phase microextraction is a solvent-free sample preparation technique in which a fused silica fiber coated with polymeric organic liquid is introduced into the headspace above the sample. The volatilized organic analytes are extracted and concentrated in the coating and then transferred to the analytical instrument for desorption and analysis. This modification of the solid-phase microextraction method (SPME) shortens the time of extraction and facilitates the application of this method to analysis of solid samples. The detection limits of the headspace SPME technique are at ppt level when ion trap mass spectrometry is used as the detector and are very similar to that of the direct SPME technique. A simple one-dimensional kinetic model has been developed to study the diffusion process involved in headspace SPME. The results from theoretical modeling are consistent with the experimental data. In the experiments, a group of organic compounds, benzene, toluene, ethylbenzene, and xylenes (BTEX), and several polynuclear aromatic hydrocarbons (PAHs) in water were analyzed by the headspace SPME technique. The sampling time for BTEX was reduced to about 1 min compared to about 5 min for direct SPME sampling of the aqueous phase. At ambient temperature, the headspace SPME technique can be used very effectively to isolate compounds with Henry's constants above 90 atm.cm3/mol (i.e, three-ring PAHs or more volatile analytes) and can also be used to sample less volatile compounds if high sensitivity can be achieved without reaching equilibrium. The equilibration time for less volatile compounds can be shortened significantly by agitation of both aqueous phase and headspace, reduction of headspace volume, and increase in sampling temperature.
Phenolic and volatile compounds play an important role in enology owing to their contribution to wine sensory properties and to their participation in various phenomena during winemaking and aging process. The objective of this work was to establish the relationship between the phenolic and volatile composition and the type of winemaking technologies. Four Castelão (Vitis vinifera, cv.) red wines were made by different winemaking technologies: carbonic maceration (maceration temperature 35°C and maceration time 21 days), stem-contact fermentation (maceration time 7 and 21 days) and non stem-contact fermentation (maceration time 7 days). Phenolic compounds were analyzed by liquid chromatography (LC) and spectrophotometric methods. The volatile composition was analyzed by HRGC and by gas chromatography–mass spectrometry (GC–MS). Multivariate analysis, i.e., clustering and principal component analysis (PCA), was applied to the results of phenolic and volatile composition. The carbonic maceration wine had less color intensity, lower concentrations of phenolic compounds and of 1-hexanol, 2-phenylethanol, diethyl succinate, and diethyl malate, but higher concentrations of benzyl alcohol and ethyl lactate than the skin fermentation wines. Stems are an important source of polyphenols, but increasing maceration time decreased both total and some individual anthocyanins. The volatile composition was not significantly affected by the presence of stems. Phenolic and volatile composition appeared a powerful tool to distinguish the wines made by different winemaking technologies, particularly to distinguish the carbonic maceration wine from the skin fermentation wines.
A method for the simultaneous determination of major (10–200 mg/l) and minor (0.1–10 mg/l) volatile compounds from wine has been optimised and validated. A 3-ml volume of wine is diluted with water (7 ml), salted with 4.5 g of ammonium sulfate and extracted with 0.2 ml of dichloromethane. The extract is injected in the split mode in a GC system, separated on a Carbowax 20M capillary column and detected by flame ionisation detection. Volatiles from wine are divided into four groups according to their behaviour in the extraction, and a specific internal standard has been selected for each group. The method allows satisfactory determination of more than 30 volatile compounds of wine. Compounds analysed include acetaldehyde, diacetyl, acetoine (3-hydroxy butanone), fusel alcohols and their acetates, and fatty acids and their ethyl esters. The linear dynamic range of the method covers the normal range of occurrence of analytes in wine and extends from at least one magnitude order to more than two, with typical r2 between 0.9938 and 0.9998. Reproducibility ranges from 3.1 to 10% (as RSD) with 5.5% as the average. The analysis of spiked samples has shown that matrix effects do not significantly affect method performance.
This article emphasises the importance of making quantitative measurements of the growth of yeast species during wine fermentations. Although such studies confirm Saccharomyces cerevisiae as the principal wine yeast, they show that indigenous species of Kloeckera and Candida make a more significant contribution to the fermentation than previously thought. Inoculation of grape juice with S. cerevisiae does not necessarily suppress growth of these indigenous species, nor does it ensure that the inoculated strain will become dominant over indigenous strains of S. cerevisiae. Factors that affect growth of yeasts during fermentation are examined along with the related aspects of stuck fermentations, killer‐yeast activity and yeast autolysis. The contribution of non‐Saccharomyces yeasts to wine quality warrants more serious consideration.
Forty-four odor-active compounds were quantified in Scheurebe and Gewürztraminer wines, respectively. Calculation of odor activity values (OAVs) of odorants showed that differences in odor profiles of both varieties were mainly caused by cis-rose oxide in Gewürztraminer and by 4-mercapto-4-methylpentan-2-one in Scheurebe. On the basis of their high OAVs, ethyl octanoate, ethyl hexanoate, 3-methylbutyl acetate, ethyl isobutyrate, (E)-β-damascenone, and 3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3H)-one (wine lactone) were further potent odorants in both varieties. The compounds were dissolved in a water/ethanol mixture in various combinations and in concentration levels equal to those in wine. The results indicated that the aromas of Gewürztraminer and Scheurebe models were in good agreement with the original wines. Keywords: Gas chromatography; stable isotope dilution assay; quantitation; white wine; Gewürztraminer; Scheurebe
2-Methylbutanoate esters, especially ethyl 2-methylbutanoate, are key contributors to fruit aroma. The biosynthetic origins and interconversions of 2-methylbutyl and 2-methylbutanoate esters in Red Delicious and Granny Smith apples were determined by feeding deuterium-labeled substrates with GC−MS identification of the deuterated aroma volatiles produced. Deuterium-labeled isoleucine was fed to apple peel, and 2-methylbutanoic-d3 acid, 2-methylbutanol-d3, and ethyl 2-methylbutanoate-d3 were fed as vapor to whole apples. An array of labeled 2-methylbutyl and 2-methylbutanoate esters was produced from each substrate with significant differences in products and product distributions between the two apple cultivars. Novel 2-methyl-(2E)-butenyl esters were identified as biosynthetic products in the aroma of Red Delicious but not Granny Smith apples. Keywords: Biosynthesis; apple; aroma volatiles; 2-methylbutyl; 2-methylbutanoate; 2-methyl-2-butenyl; deuterium
The new extraction method, so-called solid-phase microextraction (SPME), coupled with gas chromatography-mass spectroscopy (GC-MS), was examined for the determination of residues of insecticides and fungicides commonly used for vineyard protection. Aqueous solutions containing between 0 and 15% ethanol were spiked with 12 selected compounds and diphenylamine at the level of 20 ppb (v/w), extracted onto a silica fiber coated with a 100-μm thickness of poly(dimethylsiloxane), and desorbed in the chromatograph injector. The influence of ethanol on the partition equilibrium between the adsorbant and the liquid was studied for each product. In several cases, equilibria were obtained, and the extracted amounts of pesticides were shown to be dependent on the nature of the molecule and on the ethanolic content of the solution. In contrast, the time necessary to reach these equilibria was the same in the presence and absence of ethanol. Additional experiments on natural wines spiked at the same level of concentration were analyzed under the same conditions, and the results were compared with those obtained from reference solutions. Keywords: Pesticide residues; wine; solid-phase microextraction (SPME); ethanol influence
An extraction method using Amberlite XAD-2 sorbent with Freon 11 to extract wine volatiles was evaluated and compared with Freon 11 liquid/liquid extraction. The experiments were performed on a synthetic model solution containing 40 typical wine volatiles. Relative recoveries by XAD-2 extraction were measured and compared with those of liquid/liquid extraction. Results indicated that XAD-2 extraction using Freon 11 as the eluent is comparable to liquid/liquid extraction for most volatiles of interest in wine. Both sample preparation methods exhibit a high relative recovery for longer chain alcohols, esters, aldehydes, ketones, and monoterpenes. However, they show a low extraction efficiency for low molecular weight alcohols and organic acids. This was further confirmed by comparing differences in the measured concentrations of volatiles in a Riesling wine. Keywords: Wine volatiles; Amberlite XAD-2 extraction; liquid/liquid extraction; capillary gas chromatography
A fast and efficient method for analyzing wine volatiles has been developed. Twenty-six compounds can be quantified with a single-step sample treatment of only 1 h via microextraction with Freon 113. Precision, linearity, and accuracy of the method have been tested using different wines and synthetic mixtures. Detection limits are in the micrograms per liter range, and relative precision is better than 3%.
Headspace solid phase microextraction and gas chromatography/mass spectrometry were used to identify and quantify four odd-numbered methylketones in commercial Cognac brandies. These ketones are in part responsible for the desirable and complex characteristic called ‘rancio charentais’ or ‘Cognac rancio’ which is found in grape brandies aged in oak barrels for several decades. The ketones 2-heptanone, 2-nonanone, 2-undecanone and 2-tridecanone form through β-oxidation and decarboxylation of long-chain fatty acids originating from yeast metabolism. The concentrations of these ketones increased with Cognac age classification in the 42 brandies analysed, and 2-heptanone was present at the highest concentration in most samples. The average concentrations and rates of formation decreased with increasing chain length. Total concentrations ranged from 21 to 328 µg l−1. The esters propyl octanoate and ethyl octanoate followed the same trend as the methylketones and appear to play an additional role in the formation of the rancio character. Copyright © 2003 Society of Chemical Industry
Fifty-two young monovarietal red wines made with Grenache (17 samples), Tempranillo (11 samples), Cabernet Sauvignon (12 samples) and Merlot (12 samples) grapes have been analysed by HRGC–MS to obtain quantitative data on 47 odorants previously identified as potential aroma contributors by olfactometric techniques. Thirty-three odorants were present in the wines at concentrations higher than their corresponding odour thresholds. These include ethyl octanoate, β-damascenone, ethyl hexanoate, isovaleric acid and isoamyl acetate as the most important, which together with isoamyl and β-phenylethyl alcohols, fatty acids, 2,3-butanedione and ethyl butyrate are always found at concentrations higher than their odour thresholds. In some cases the ethyl esters of isobutyric and isovaleric acids, β-ionone, methionol, isobutyric acid, ethyl cinnamate, ethyl dihydrocinnamate, γ-nonalactone, eugenol, c-3-hexanol, geraniol, guaiacol, 3-isobutyl-2-methoxypyrazine, 4-ethylguaiacol, acetoin and t-whiskylactone were at a concentration high enough to be odour-active. There were 30 compounds that were found to differ significantly between varieties. These include 3-isobutyl-2-methoxypyrazine, isoamyl acetate, isovaleric acid, ethyl isobutyrate, ethyl isovalerate, fusel alcohols, c-3-hexenol, methionol, eugenol, guaiacol and γ-nonalactone.© 2000 Society of Chemical Industry
Wood maturation of red wine produces complex interactions between oak extracted compounds and pre-existing components in wine. Wood contributes with some aroma volatiles; but the whole volatile fraction, including the volatiles extracted from grape or produced during fermentation, could be involved in interactions with the non-volatile fraction. Samples of red wine with increasing time of wood contact, matured in 25 l casks of new American oak, were analysed on their volatile composition both in solution and headspace, and phenolic components. There was an increase of acetic acid and acetate esters as the time of wood contact increased. On the other hand, ethyl esters decreased as the time in wood increased. Some volatiles showed different behaviour when comparing their relationship between headspace and solution from two different casks, even though they were treated as replicates. This different evolution among casks was also consistent with different evolution of phenolic compounds, suggesting that there was an interaction among the volatile fraction and phenolic components.
Caffeine concentrations in beverages were determined using a simple and rapid method based on microextraction of caffeine onto the surface of a fused-silica fiber. The uncoated fiber was dipped into the beverage sample for 5 min after the addition of isotopically labeled (trimethyl 13C)caffeine. The adsorbed caffeine was then thermally desorbed in a conventional split/splitless injection port, and the concentration of caffeine was determined using gas chromatography with mass spectrometric detection. Quantitative reproducibilities were ca. 5% (relative standard deviation) and the entire scheme including sample preparation and gas chromatographic analysis was completed in ca. 15 min per sample. The potential of the microextraction technique for the analysis of flavor and fragrance compounds in non-caffeinated beverages is also demonstrated. Since no solvents or class-fractionation steps are required, the method has good potential for automation.
Wines produced from Baga native variety from the Portuguese Bairrada Appellation, harvest 2000, were submitted to a liquid–liquid continuous extraction with dichloromethane and analysis by gas chromatography–mass spectrometry (GC–MS). A total of 53 compounds were identified and quantified. This wine has 225 mg l−1 volatile compounds, which include aliphatic and aromatic alcohols (44%), acids (27%), esters (15%), lactones (6%), amides (5%), and phenols (1%). To achieve the identification of the major would-be impact odourants, the aroma index was calculated using the concentration of each volatile component and the corresponding odour threshold reported in the literature. This methodology proved suitable, as a preliminary step, for the determination of the would-be impact odourants of Baga wine. From the 53 compounds identified, nine were determined as the most powerful odourants: guaiacol, 3-methylbutanoic acid, 4-ethoxycarbonyl-γ-butyrolactone, isobutyric acid, 2-phenylethanol, γ-nonalactone, octanoic acid, ethyl octanoate and 4-(1-hydroxyethyl)-γ-butyrolactone. These data suggest Baga wine as a fruity-type product with an aroma correlated to a restricted number of compounds.
A method for the simultaneous determination of major (10–200 mg/l) and minor (0.1–10 mg/l) volatile compounds from wine has been optimised and validated. A 3-ml volume of wine is diluted with water (7 ml), salted with 4.5 g of ammonium sulfate and extracted with 0.2 ml of dichloromethane. The extract is injected in the split mode in a GC system, separated on a Carbowax 20M capillary column and detected by flame ionisation detection. Volatiles from wine are divided into four groups according to their behaviour in the extraction, and a specific internal standard has been selected for each group. The method allows satisfactory determination of more than 30 volatile compounds of wine. Compounds analysed include acetaldehyde, diacetyl, acetoine (3-hydroxy butanone), fusel alcohols and their acetates, and fatty acids and their ethyl esters. The linear dynamic range of the method covers the normal range of occurrence of analytes in wine and extends from at least one magnitude order to more than two, with typical r2 between 0.9938 and 0.9998. Reproducibility ranges from 3.1 to 10% (as RSD) with 5.5% as the average. The analysis of spiked samples has shown that matrix effects do not significantly affect method performance.
The application of solid-phase microextraction (SPME) for the flavour analysis of strawberry and apple fruits has been studied. An SPME liquid sampling method based on poly(acrylate)-coated fibers was developed. Immediate thermal desorption of the adsorbed compounds led to the formation of Maillard products due to the high concentration of carbohydrates and amines in the samples, remaining on the surface of the fiber. Artefact formation was significantly reduced by rinsing the fiber with water prior to thermal desorption.
A hundred strains of Saccharomyces cerevisiae were examined for the ability to produce higher alcohols. In the strains tested the production of higher alcohols was found to be an individual strain characteristic and, as such, was statistically significant. The characteristics of the strains used (flocculation ability, foaming ability, killer character, and non-H2S production) were found to be uncorrelated to isobutanol and isoamyl alcohol production, whereas the production of high levels of n-propanol was found to be related to inability to produce H2S. This, in turn, suggests a link to methionine biosynthesis.
The aroma of wine consists of 600 to 800 aroma compounds from which especially those, typical for the variety, are already present in the grapes. There are significant varietal differences between the aromagrams ('fingerprint patterns'). Thus the amount of some flavour compounds ('key substances') shows typical dependence on the variety. Especially monoterpene compounds play an important role in the differentiation of wine varieties. The German white wines can be differentiated into three groups only by quantitative determination of 12 monoterpenes ('terpene profile'). These groups are: 'Riesling type', 'Muscat type' and 'Silvaner-Weissburgunder type'. Such 'terpene profiles' are also useful for the separation of real Riesling wines from others called Riesling (e.g. Welschriesling, Kap Riesling, Emerald Riesling) but not produced from grapes of the variety Riesling. Including further components and by means of statistical methods (discriminant analysis) even the different varieties within the mentioned groups for instance the 'Riesling'-group (e.g. Riesling, Kerner, Ehrenfelser, Bacchus, Müller-Thurgau) can be separated from each other. An analytical characterization of the neutral ('Silvaner-type') grape varieties Silvaner, Ruländer (Pinot gris), Weissburgunder (Pinot blanc) is also possible with about 20 compounds (e.g. monoterpenes, alcohols). Computing at the same time free and glycosidically bound aroma components (monoterpenes, alcohols, norisoprenes) in discriminant analysis the characterization of the neutral grape varieties can be considerably improved. To identify compounds causing 'off-flavours' sniffing technique is the method of choice. The off-flavour is pinpointed during gas chromatographic separation of the complex aroma mixture by effluent sniffing. Once allocated, the chemical nature of the off-flavours is elucidated by spectroscopic methods. Substances contributing to the green pepper taint, the strawberry note, moussiness, corkiness, etc. in wine could be found in this way.
The cis- and trans-isomers of 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone, the so-called oak lactones, are derived from oakwood, and the cis-isomer is an important contributor to wine flavour. Their deuterium-labelled forms, [2H4]cis-oak lactone and [2H4]trans-oak lactone, were synthesised from the unlabelled analogues, and were utilised in a new method employing gas chromatography-mass spectrometry to determine the concentration of these compounds in wine or extracts of oak shavings in a single analysis. The method can employ either liquid-liquid extraction or solid-phase microextraction, and is both rapid and accurate. There was some artefactual generation of cis-oak lactone during the analysis of model wine extracts of unheated oak shavings when diethyl ether extraction and injector block temperatures at or above 225 degrees C were employed.
Nine Saccharomyces cerevisiae and four Saccharomyces bayanus strains used in the production of Trebbiano wine were examined. The aim of this study is to evaluate the different abilities of various yeast strains in wine-making. The possibility of yeast discrimination on the basis of their volatile production is another possibility. Wine chemical analyses showed statistically significant differences depending on the yeast strain used. Some compounds such as 2-phenylethanol, 2-phenethyl acetate, ethyl lactate, 3-ethoxypropanol, and, to a lesser extent, diethyl succinate and propionic acid characterized examined Saccharomyces bayanus yeasts. Moreover, these strains did not produce any undesirable compounds, such as acetic acid and sulfur anhydride. For these reasons and because they synthesized malic acid, they could be more suitable for white wine production. The other yeasts showed great differences, which are difficult to correlate with the strain. However, some strains had peculiar characteristics, such as an uncommonly high concentration of n-propanol and 3-ethoxypropanol.
The aroma extract dilution analysis method was used to detect the impact odorants of Bordeaux Cabernet Sauvignon and Merlot wines extracts, as well as those of the extracts of the corresponding Cabernet Sauvignon juice and dry yeasts used for its fermentation. The wines and the yeasts were extracted using dichloromethane, and the juice was extracted using Amberlite XAD-2. Structural identification of the impact odorants using gas chromatography-mass spectrometry and atomic emission detection (sulfur acquisition) was achieved after enrichment of these extracts by silica gel and Affi-Gel 501 chromatography. The same odorants (with the exception of dimethyl sulfide among 48) were detected in both wine extracts, with about the same flavor dilution (FD) factors. The 18 impact odorants detected in the Cabernet Sauvignon juice and dry yeast extracts were also found in the wine extracts. The odorants with the highest FD factors were 3-(methylsulfanyl)propanal, (E,Z)-nona-2, 6-dienal, and decanal in the juice extract, 2-methyl-3-sulfanylfuran, 3-(methylsulfanyl)propanal, 2-/3-methylbutanoic acids, and phenylethanal in the dry yeast extract, and 2-/3-methylbutanols, 2-phenylethanol, 2-methyl-3-sulfanylfuran, acetic acid, 3-(methylsulfanyl)propanal, 2-/3-methylbutanoic acids, beta-damascenone, 3-sulfanylhexan-1-ol, Furaneol, and homofuraneol in the wine extracts. Determination of the odor thresholds of some of these impact odorants was carried out.
A biocatalyst was prepared by immobilization of Saccharomyces cerevisiae strain AXAZ-1 on delignified cellulosic material (DCM). Repeated batch fermentations were conducted using these biocatalysts and free cells, separately, at temperatures of 20, 15, and 10 degrees C. Solid phase microextraction (SPME) was used in monitoring the formation of volatile alcohols, acetate esters, and ethyl esters of fatty acids. The kinetics of volatile production were similar for free and immobilized cells. In all cases immobilized cells showed a better rate of volatile production, which was directly connected to sugar consumption. The main difference observed was in propanol production, which increased with temperature decrease for the immobilized cells, whereas it remained constant for the free ones. In the case of immobilized cells significant amounts of esters were also produced. It is well-known that esters contribute to the fruity aroma of wine. It was also established that SPME is a very sensitive, accurate, and reliable technique and can be used without any reservation in the characterization of volatile constituents of wine.
Headspace solid-phase microextraction (HS-SPME) was studied for the high-resolution gas chromatographic (HRGC) analysis of esters in wines. Five different SPME fibers were tested and the influence of different factors such as temperature and time of desorption, extraction time, extraction technique, stirring, sample and vial volume, sugar and ethanol content were studied and optimised using model solutions. The proposed HS-SPME-GC method is an appropriate technique for the quantitative analysis of esters in dry and sweet white wines.
The successful separation of 2- and 3-methyl-substituted positional isomers of butanol, butyl acetate, and butanoic acid and its ethyl ester, is reported. These compounds are of interest in the study of wine flavour, however the separation of the 2- and 3-methyl isomers may present problems, and more so in the presence of the wine matrix components, when single capillary column gas chromatography (GC) is used. The strategy to achieve separation was based on the use of shape-selective cyclodextrin derivative (CDD) capillary columns (commonly referred to as chiral columns). These columns provide simultaneous resolution of the enantiomeric pairs of the 2-methyl isomers, and at the same time the ability to separate the 3-methyl isomer from the 2-methyl is achieved in all but the case of the ( S)-2- and 3-methylbutanol. The advantages of using shape-selective columns to perform this study is demonstrated, with coupling of two CDD columns giving improved separations of these compounds. Although these compounds are relatively volatile, cryogenic modulated comprehensive two-dimensional GC was shown to provide good pulsed peak profiles with chiral separation in the first dimension when a thicker film trapping column segment was employed. The components of interest were well separated from other wine matrix components.
The free volatiles, as well as those released from the glycosidically bound forms by enzyme hydrolysis, have been analyzed to chracterize young Tannat wines from two successive vintages. The Tannat wine showed some aroma profile peculiarities detected in the free forms but, above all, in the bound fraction for the level and profile of the norisoprenoidic fraction. Among the free volatile compunds, a rather low content of C(6) alcohols with a prevalence of cis-3-hexen-1-ol on the trans form and sometimes a remarkable level of trans-2-hexen-1-ol seem to be typical for the variety. C(13)-norisoprenoidic and monoterpenic volatiles made up approximately 42% of the total level of the volatiles observed in the glycosidase enzyme-released fraction. The other volatiles were C(6) alcohols (6%) and benzenoid compounds (51%). The dominating monoterpene alcohols were the cis and trans isomers of 3,7-dimethyl-1,6-octadiene-3,8-diol (8-hydroxylinalool). The C(13)-norisoprenoid pattern was composed by 3-hydroxy-beta-damascone, 3-oxo-alpha-ionol, vomifoliol, 4-oxo-beta-ionol, 3-oxo-7,8-dihydro-alpha-ionol, 4-oxo-7,8-dihydro-beta-ionol, grasshopper ketone, and 7,8-dihydrovomifoliol.
Flor yeast Saccharomyces cerevisiae (capensis G1) strain assimilates gluconic acid during the aerobic biological aging process of sherry wines and exerts significant changes on the final volatile compounds of wines, especially a decrease in volatile acidity and butanoic, isobutanoic, 2-methylbutanoic, and 3-methylbutanoic acids. This decrease may have a favorable effect on the quality of sherry wines.