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Determining wine aroma from compositional data
Australian Journal of Grape and Wine Research
Abstract
The value of, opportunities provided by, and the difficulties in elucidating the exact contribution that chemical compounds make to wine aroma and flavour are outlined and highlighted in this review. This paper provides an overview of the current understanding of relationships between wine sensory properties and volatile chemical composition through a discussion of recent studies where accurate, precise chemical data have been obtained for compounds shown by quantitative gas chromatography-olfactometry (GC/O) to be odour active in a sample. A centrepiece of this discussion is a compilation of compounds indicated to be most important to wine aroma. This is followed by a consideration of the limitation of odour activity values obtained by GC/O with particular reference to wine esters and volatile thiol compounds. The strengths of sensory descriptive analysis and its associated statistical methodologies to complement chemical composition data for aroma compounds are also explored. Grape flavour precursor compounds and the development of methods for their rapid quantification are then discussed in the context of the role of precursors contributing to wine aroma. Finally, an assessment is given of the likelihood in the near future of developing analytical strategies to measure wine flavour in relation to consumer expectations on the one hand, and on the other, to viticultural management practices to influence grape flavour composition.
... Monoterpenes trans-furan linalool oxide 3000 [42] Sweet, floral [43] cis-furan linalool oxide 6000 [42] Floral, sweet, woody [43] linalool 25 [44] Citrus, floral, sweet [45] α-terpineol 250 [42] Floral, sweet [45] terpinen-4-ol 250 [45] Sweet, herbaceous [45] β-citronellol 100 [46] Lemongrass [46] nerol 400 [46] Lime, floral-hyacinth, roses [46] geraniol 30 [44] Rose, geranium [44] geranic acid 40 [47] Green [47] trans-rose oxide 100 [44] Rose-like, floral, sweet [43] cis-rose oxide 100 [44] Floral, lychee-like, rose [44] limonene 200 [48] Orange, mint, lemon, floral, citrus [49] myrcene 14 [50] Green, floral, grass, citrus [49] hotrienol 110 [43] Floral, green, woody [43] trans-pyran linalool oxide 3000-5000 [51] Sweet, floral, earthy [43] cis-pyran linalool oxide 3000-5000 [51] Sweet, floral, earthy [43] diendiol I n.d. n.d. ...
... Monoterpenes trans-furan linalool oxide 3000 [42] Sweet, floral [43] cis-furan linalool oxide 6000 [42] Floral, sweet, woody [43] linalool 25 [44] Citrus, floral, sweet [45] α-terpineol 250 [42] Floral, sweet [45] terpinen-4-ol 250 [45] Sweet, herbaceous [45] β-citronellol 100 [46] Lemongrass [46] nerol 400 [46] Lime, floral-hyacinth, roses [46] geraniol 30 [44] Rose, geranium [44] geranic acid 40 [47] Green [47] trans-rose oxide 100 [44] Rose-like, floral, sweet [43] cis-rose oxide 100 [44] Floral, lychee-like, rose [44] limonene 200 [48] Orange, mint, lemon, floral, citrus [49] myrcene 14 [50] Green, floral, grass, citrus [49] hotrienol 110 [43] Floral, green, woody [43] trans-pyran linalool oxide 3000-5000 [51] Sweet, floral, earthy [43] cis-pyran linalool oxide 3000-5000 [51] Sweet, floral, earthy [43] diendiol I n.d. n.d. ...
... Monoterpenes trans-furan linalool oxide 3000 [42] Sweet, floral [43] cis-furan linalool oxide 6000 [42] Floral, sweet, woody [43] linalool 25 [44] Citrus, floral, sweet [45] α-terpineol 250 [42] Floral, sweet [45] terpinen-4-ol 250 [45] Sweet, herbaceous [45] β-citronellol 100 [46] Lemongrass [46] nerol 400 [46] Lime, floral-hyacinth, roses [46] geraniol 30 [44] Rose, geranium [44] geranic acid 40 [47] Green [47] trans-rose oxide 100 [44] Rose-like, floral, sweet [43] cis-rose oxide 100 [44] Floral, lychee-like, rose [44] limonene 200 [48] Orange, mint, lemon, floral, citrus [49] myrcene 14 [50] Green, floral, grass, citrus [49] hotrienol 110 [43] Floral, green, woody [43] trans-pyran linalool oxide 3000-5000 [51] Sweet, floral, earthy [43] cis-pyran linalool oxide 3000-5000 [51] Sweet, floral, earthy [43] diendiol I n.d. n.d. ...
Among the Moscato grapes, Moscato Giallo is a winegrape variety characterised by a high content of free and glycosylated monoterpenoids, which gives wines very intense notes of ripe fruit and flowers. The aromatic bouquet of Moscato Giallo is strongly influenced by the high concentration of linalool, geraniol, linalool oxides, limonene, α-terpineol, citronellol, hotrienol, diendiols, trans/cis-8-hydroxy linalool, geranic acid and myrcene, that give citrus, rose, and peach notes. Except for quali-quantitative analysis, no investigations regarding the isotopic values of the target volatile compounds in grapes and wines are documented in the literature. Nevertheless, the analysis of the stable isotope ratio represents a modern and powerful tool used by the laboratories responsible for official consumer protection, for food quality and genuineness assessment. To this aim, the aromatic compounds extracted from grapes and wine were analysed both by GC-MS/MS, to define the aroma profiles, and by GC-C/Py-IRMS, for a preliminary isotope compound-specific investigation. Seventeen samples of Moscato Giallo grapes were collected during the harvest season in 2021 from two Italian regions renowned for the cultivation of this aromatic variety, Trentino Alto Adige and Veneto, and the corresponding wines were produced at micro-winery scale. The GC-MS/MS analysis confirmed the presence of the typical terpenoids both in glycosylated and free forms, responsible for the characteristic aroma of the Moscato Giallo variety, while the compound-specific isotope ratio analysis allowed us to determine the carbon (δ13C) and hydrogen (δ2H) isotopic signatures of the major volatile compounds for the first time.
... The ethyl esters were predominantly separated in the first dimension on the apolar stationary phase and were less retained in the 2 D column compared to other volatile classes (Fig. S5). Several of the volatile esters identified in this study have been reported to contribute to the aroma of white wine [56], including compounds such as ethyl butanoate (17), ethyl hexanoate (83), ethyl octanoate (165), isoamyl acetate (35) and 2-phenyl ethyl acetate (160), with considerable variation in their abundances noted across the analysed wine samples (Figs. S1 and S2). ...
... As for the esters, the majority of these (18 compounds) were detected in both wine styles, but their levels varied significantly between the wine samples analysed. Influential alcohols in white wine aroma detected include isoamyl alcohol (7) and 2-phenylethyl alcohol (144) [56]. ...
... Volatile acids are normally associated with unpleasant aroma attributes when present at high levels [56,58]. Volatile fatty acids also occur in most wines in high abundance. ...
... The FC values of hexanoic acid and octanoic acid are more than 1 (1.172 and 1.309). About ketones, the relative contents of acetoin with butter and creamy aroma (Francis and Newton, 2005) and 2-acetylfuran with nutty and sweet caramel-like aroma (www.chemsrc.com) were higher in the mixed fermented icewine than in the pure fermented one, and their FC values were 1.259 and 2.443, respectively. ...
... Moreover, β-damascenone, which has an intense rose fragrance, honey flavor, and apricot peach aromas, has been reported as a key odorant in Vidal blanc icewine profiles (Ma et al., 2017;Huang et al., 2018;Tang et al., 2021). Notably, the odor threshold of β-damascenone is very low (0.05 g/L), and small changes in the concentration can markedly influence sensory evaluations of wine (Francis and Newton, 2005). Therefore, C. railenensis in mixed culture fermentation can increase β-damascenone and its pleasant aroma. ...
... Hexanoic acid and octanoic acid are medium-chain fatty acids that can give the wine a cheesy and fatty odor (Francis and Newton, 2005;Hong et al., 2021); and they are in the mixed culture fermented icewine were higher levels than those in the icewine of control fermentation. However, this was inconsistent with the result by Van Wyk et al. (2020), who stated that hexanoic acid and octanoic acid in wines of mixed culture fermentation were not higher than those in pure fermented wines. ...
Mixed culture fermentation with non- Saccharomyces yeasts and Saccharomyces cerevisiae as multi-starters has more advantages than spontaneous fermentation, and wine products with distinctive and pleasant aromas can fulfill the diverse demands of consumers. This study was carried out to illuminate the effect of sequential inoculation of indigenous Candida railenensis and S. cerevisiae on alcoholic fermentation behavior and chemical and aromatic characteristics of Vidal blanc icewine. During the mixed culture fermentation, C. railenensis was present in the initial and middle stages but was absent after 14 days. The results of basic chemical parameters showed that the glycerol content in the mixed culture-fermented icewine was higher than that of the pure fermented icewine, but the acetic acid content was the opposite. In terms of volatile aroma compounds, C. railenensis in the mixed culture fermentation reduced some metabolites such as lower alcohols, 1-hexanol, 3-methylthiopropanol, and their unpleasant notes and increased the production of some desired volatile aroma compounds such as benzaldehyde, β-damascenone, 2-furanmethanol, and 5-methyl furfural associated with rose, honey, nut, and caramel characteristics. Furthermore, C. railenensis also changed the sensory performance of icewine by participating in the fermentation of S. cerevisiae . These findings suggest that C. railenensis with positive enological properties has the ability to be used in icewine production, which has never been reported before.
... Knowing the nature and origin of the compounds that contribute the most to wine aroma is of great importance for wine producers who, by properly choosing the harvest date and using adequate vinification technologies, can make the most of the aromatic potential of the variety and thus contribute to the quality of the wine [3]. Despite the large number of volatile aromatic compounds present in wine, only some of them will influence the formation of the final wine "flavor", that is, the synergy of olfactory, gustatory, and tactile sensations of wine [4]. To adequately understand the chemical compounds in wine that confer desirable sensory characteristics, information regarding both the chemical nature and the sensory properties of a wine, or of those components in the wine, is necessary [4]. ...
... Despite the large number of volatile aromatic compounds present in wine, only some of them will influence the formation of the final wine "flavor", that is, the synergy of olfactory, gustatory, and tactile sensations of wine [4]. To adequately understand the chemical compounds in wine that confer desirable sensory characteristics, information regarding both the chemical nature and the sensory properties of a wine, or of those components in the wine, is necessary [4]. The information of the two different types of tools, instrumental and sensory data, is very important to establish the quality of wine [4,5]. ...
... To adequately understand the chemical compounds in wine that confer desirable sensory characteristics, information regarding both the chemical nature and the sensory properties of a wine, or of those components in the wine, is necessary [4]. The information of the two different types of tools, instrumental and sensory data, is very important to establish the quality of wine [4,5]. ...
The majority of chemical compounds that contribute to varietal aroma originate from grape skin. To investigate the differences between volatile aroma compounds when different mac-eration conditions are applied, a total of six vinification treatments were carried out on Malvazija istarska (Vitis vinifera L.) variety, non-maceration control treatment (C), pre-fermentative two days cryomaceration treatment at 8 °C (CRYO), seven days maceration treatment at 16 °C (M7), 14 days maceration treatment at 16 °C (M14), and prolonged post-fermentative maceration treatments at 16 °C for 21 day (M21) and 42 days (M42). Wines were subjected to GC/MS and sensory analysis. Obtained results showed that prolonged post-fermentative maceration treatments contained the highest concentration of total volatile aroma compounds, precisely monoterpenes, alcohols, and other esters. Contrary, C and CRYO wines resulted in highest concentration of ethyl and acetate esters, and fatty acids. In addition, sensory analysis showed that longer maceration treatment wines (M14, M21, M42) were characterized by more aroma complexity, varietal flowery typicity, pronounced fruitiness, with accentuated dried fruit, moderate honey, and herbal notes. Obtained results can provide valuable information to producers when choosing an appropriate vinification technique based on the desired wine style which may lead to a further diversification of white wine market.
... The aroma of wine consists of a hundred different volatile compounds at concentrations spanning several orders of magnitude [86]. A characteristic wine aroma depends on trace components with very strong odors [86]. ...
... CYP71, CYP72, CYP75, CYP76, CYP81, CYP82, and CYP89 genes are enlarged in the grapevine genome and are involved in secondary metabolism and are differentially expressed during four different stages of berry development [83][84][85]. The aroma of wine consists of a hundred different volatile compounds at concentrations spanning several orders of magnitude [86]. A characteristic wine aroma depends on trace components with very strong odors [86]. ...
... The aroma of wine consists of a hundred different volatile compounds at concentrations spanning several orders of magnitude [86]. A characteristic wine aroma depends on trace components with very strong odors [86]. Among monoterpenes, which are important constituents of the aromas in wines, wine lactone is a bicyclic monoterpene lactone that has the most potent odor [87]. ...
Cytochromes P450 are ancient enzymes diffused in organisms belonging to all kingdoms of life, including viruses, with the largest number of P450 genes found in plants. The functional characterization of cytochromes P450 has been extensively investigated in mammals, where these enzymes are involved in the metabolism of drugs and in the detoxification of pollutants and toxic chemicals. The aim of this work is to present an overview of the often disregarded role of the cytochrome P450 enzymes in mediating the interaction between plants and microorganisms. Quite recently, several research groups have started to investigate the role of P450 enzymes in the interactions between plants and (micro)organisms, focusing on the holobiont Vitis vinifera. Grapevines live in close association with large numbers of microorganisms and interact with each other, regulating several vine physiological functions, from biotic and abiotic stress tolerance to fruit quality at harvest.
... These results prove that the method we developed is adapted, from an oenological point of view, to the vinification of white wines in very small volumes. Numerous studies have been conducted over the last decades to better understand the origin of grape and wine aroma (Guth, 1997;Ferreira et al., 2000;Francis and Newton, 2005;Ebeler and Thorngate, 2009). Given the importance of the aroma on the quality of the wine, we analysed the volatile compounds of the wine by GC-MS. ...
... Nevertheless, wine aromas do not only depend on the most abundant compounds but are also largely influenced by compounds present at low concentrations (Francis and Newton, 2005). Some of these compounds originating from grapes exhibit very strong odours, contributing to the varietal aroma of wines. ...
The quality of wine largely depends on aroma perception, but the genetic basis explaining the variations of aroma compound concentrations in wines is still fragmentary. To unravel links between genetic variations and aroma compound variations in hundreds of genotypes, we developed a small-scale, high-throughput test-tube vinification (TTV) method capable of producing white wines that reveal the genetic potential at the scale of a single vine stock. We evaluated this method on commercial grapevine varieties (Riesling, Gewurztraminer, Chardonnay, Chasselas, Floreal, Muscat à petits grains blancs) and genotypes resulting from a bi-parental cross, covering a wide aromatic palette. The wines produced were described by usual oenological parameters and GC-MS profiling of volatile compounds. We compared the wines obtained with the TTV method to commercial wines and to wines obtained from larger fermentation volumes (5–10 L). Our results show that the TTV method is suitable to produce white wines on a very small scale, i.e., less than 100 mL and that these small-scale wines faithfully reflect the aromatic potential of the different varieties, as would larger volume methods. The proposed method is a high-throughput approach to assess the oenological potential of hundreds of grapevine genotypes from grape material harvested on a single vine. This wine-focused direct phenotyping method will pave the way for a better understanding of the genetic determinism of wine aromas, especially for molecules that are not directly present in grapes, such as volatile thiols and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN).
... The use of pure yeast cultures, pioneered by Christian Hansen in the 1880s, greatly improved the consistency and quality of beer. Moreover, the increasing popularity of both the craft beer market (Garavaglia and Swinnen, 2018) and the consumer interest in new beer styles (Aquilani et al., 2015;Romano et al., 2023) have stimulated the research for new brewing yeasts (Gibson et al., 2017;Hittinger et al., 2018). Nowadays, different strategies are available for providing new starter cultures, such as evolution, mutagenesis, breeding, and yeast isolation from various environmental niches (Steensels et al., 2014a,b;Berbegal et al., 2019). ...
... The comparison of the ANOVA results (Supplementary Table 2) and the sensory radar plots (A-B) (Figure 3), indicated that all IGA beers showed high scores (≥3) for "olfactory finesse" and "olfactory intensity, " probably due to the complexity of volatile profiles characterized by molecules belonging to different classes. Some of them, having an OAV > 1, directly affected odor perception, while the molecules having an OAV < 1 might have contributed to the beer flavor through the additive effects of compounds with similar structure or odor (Francis and Newton, 2005). All beers were characterized by medium-high scores for fruity and floral descriptors, which are influenced by wine must addition and then by yeast action (De Francesco et al., 2021). ...
This study investigated the influence of three Saccharomyces cerevisiae strains, selected from different matrices - CHE-3 (cherry), P4 (sourdough) and TA4-10 (grape must) - on characteristics of Italian Grape Ale (IGA) beers obtained at microbrewery scale. A multidisciplinary approach, combining results from analysis of chemical, volatile and organoleptic profiles of the beers, was adopted to underline the relationships between yeast starter and the quality of final products. Detection volatile organic compounds (VOCs) by Gas-Chromatography coupled with Mass Spectrometry (GC-MS) after extraction carried out by head-space micro-extraction (HS-SPME) revealed that the beer obtained by P4 strain differed from the others for its higher concentrations of esters, alcohols, and terpenes as confirmed by PCA (principal component analysis) and Cluster heatmap. Furthermore, sensorial analysis and consumer test showed that this sample differed from others by more pronounced notes of “fruity smell and floral” and “olfactory finesse,” and it was the most appreciated beer for smell, taste, and overall quality. Conversely, CHE-3 was the sample with the lowest concentrations of the identified volatiles and, together TA4-10, showed the highest scores for smoked, yeast, malt, and hop notes. As far as we know, these are the first results on the application of indigenous S. cerevisiae strains in the production of craft IGA beers analyzed through a complex multivariate approach.
... They are yielded by yeast metabolism and esterification reactions [24]. The most important from the aromatic point of view include the ethylic esters of fa y acids and acetates of alcohols [25]. In terms of primary aromas, the concentration of esters changes during wine aging, but not in a unique way. ...
... They usually undergo esterification reactions with the alcohols present in wine, and hence their concentration is limited by this occurrence. The most abundant was decanoic acid; however, its concentration was largely below the odor threshold of 1000 µg/L, as reported by some authors [25]. Total fa y acids concentration goes from 46 µg/L for CT to 120 for FA. ...
The main purpose of this study was to characterize Freisa red wines from Piedmont (northern Italy) according to their volatile organic compounds (VOCs) and elemental composition. Moreover, the authors investigated whether it was possible to distinguish among the five different DOCs produced in Piedmont on the basis of these chemical parameters. The VOCs profile of Freisa wines was very similar, and the most abundant species detected were isoamyl alcohol, phenylethyl alcohol, ethyl octanoate, and diethyl succinate. Conversely, elemental composition allowed us to partially distinguish one Freisa DOC with respect to the others. Multivariate statistical analysis applied to elemental composition revealed differences among Freisa wines and other red wines from different regions of Italy. In particular, Freisa wines featured higher concentrations of Cr and Ni metals, which are strongly correlated with the composition of the soil of Piedmont. These two elements are hence good candidates as chemical markers for Freisa wines from Piedmont.
... Odor threshold values and odor activity values (OAVs) are frequently used to show the relative contribution and the relative importance of the identified and quantified volatile odor compounds in the wines' aromas [40]. To determine the effective odor active compounds (OACs) in the analyzed monovarietal red wines, and build, for each variety, an aroma characterization, OAVs were determined as the quotient between the concentration of each identified compound in each variety and its odor perception threshold. ...
... These wines showed the greatest appreciation by the judges during the sensory analysis, also revealing the highest scores for the attribute 'Intensity of Odor'. Concerning the 'Merlot' variety, these results agree with high plasticity in response to climate change, reported by other researchers [40] to this variety. Looking at the data from the general chemical analysis, these samples also showed similar patterns in terms of alcoholic strength, titratable acidity and reducing substances. ...
Adaptation strategies in the wine sector consist of the use of cultural techniques to limit damages caused by climate change, using, among other resources, varieties better adapted to the scenarios of abiotic stress exacerbation, namely water and thermal stress, as well as those more tolerant to heatwaves. With the intention to determine the aromatic characterization of ten monovarietal wines produced from cultivars with high productive performance in a global warming scenario (‘Petit Verdot’, ‘Marselan’, ‘Merlot’, ‘Touriga Franca’, ‘Syrah’, ‘Vinhão’, ‘Bobal’, ‘Preto Martinho’, ‘Trincadeira’, and ‘Alicante Bouschet’), grown in Esporão vineyard (Alentejo, Portugal) and submitted to deficit irrigation (Ks ± 0.5), their aromatic character has been analyzed. Each grape variety was vinified at a small scale, in duplicate, and the wines were evaluated by a sensory panel, which rated several sensory attributes (visual, olfactory, and gustatory). Sensory analysis revealed a discrete appreciation for the monovarietal wines tasted, showing a differentiation at the olfactory level that was not too marked, although present, between the samples. The free volatile compounds were analysed using gas chromatography-olfactometry (GC-O), identified using a gas chromatography-mass spectrometry (GC-MS) technique and semi-quantified using the gas chromatography-flame ionization detector (GC-FID) technique. Based on the interpolation of the results of the various statistical analyses carried out, 49 probable odor active compounds (pOACs) were identified and based on the odor activity values (OAVs), 24 of them were recognized as odor active compounds (OACs) originated mainly during the fermentation processes. An aromatic characterization of the varieties has been proposed.
... 21 Among esters, ethylic esters of fatty acids and acetates of higher alcohols play the major role in determining wine aroma, since they provide fruity scents and are characterized by low odor thresholds. 22 The content of esters changes during aging of wine according to storage temperature and pH of wine. In fact, both hydrolysis reactions, which decrease the ester concentration, and esterification reactions occur depending on the factors mentioned. ...
... The most abundant was decanoic acid, which provides an unpleasant odor of rancid and fat. Its odor threshold is 1000 μg/L, as reported by some authors 22 ; because we did not perform quantitative measures, we did not perceive its characteristic unpleasant odor in Pelaverga wines analyzed, and therefore we assume that its concentration was below the odor threshold. Nonanoic acid is described to have a nutty odor and is one of the VOCs whose concentration increases when grapes are subjected to withering. ...
Background
The characterization of a typical red wine from Piedmont (north‐west Italy), Pelaverga, was performed by means of headspace solid phase microextraction coupled to gas chromatography–mass spectrometry. Two different kinds of Pelaverga are known, hystorical and Verduno, which differ with the area of production. The main volatile compounds of the wine were identified and semi‐quantified. Principal components analysis (PCA) was performed to identify possible clusters among the different samples analyzed.
Results
Forty‐eight volatile compounds were unambiguously identified in the wines sampled. The two types of Pelaverga analyzed displayed a very similar volatile profile. The most abundant volatile compounds were two esters, ethyl octanoate and diethyl succinate, and two alcohols, isoamyl alcohol and ethyl phenyl alcohol. Few varietal compounds were detected, probably due to their low concentration; among these, we were not able to detect rotundone, which is reported to impart characteristic spicy notes to this kind of wine. Application of PCA did not allow to differentiate between the two types of Pelaverga on the basis of their volatile profile.
Conclusion
The present work is, to the best of our knowledge, the first complete report about the volatile profile of Pelaverga wines and represents the first step of a research project aiming at characterizing food products from Piedmont on the basis of chemical parameters. Differentiation between the two types of Pelaverga will likely require the determination of different chemical parameters in conjunction with volatile compounds.
... The aromas and sensory thresholds of wine esters are detailed in Table 3. The most important esters present in wine are the ethyl esters of fatty acids, including ethyl acetate, ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, hexyl acetate, isoamyl acetate, isobutyl acetate, and phenylethyl acetate [34,37,38]. ...
Volatilomics is a scientific field concerned with the evaluation of volatile compounds in the food matrix and methods for their identification. This review discusses the main groups of compounds that shape the aroma of wines, their origin, precursors, and selected metabolic pathways. The paper classifies fruit wines into several categories, including ciders and apple wines, cherry wines, plum wines, berry wines, citrus wines, and exotic wines. The following article discusses the characteristics of volatiles that shape the aroma of each group of wine and the concentrations at which they occur. It also discusses how the strain and species of yeast and lactic acid bacteria can influence the aroma of fruit wines. The article also covers techniques for evaluating the volatile compound profile of fruit wines, including modern analytical techniques.
... This is not the case with esters, where these volatile substances contribute to the aromatic profile of the young wine. The main components of the 'fruity' aroma are considered to be 3-methyl-1-butyl acetate, hexyl acetate, and 2-ethyl hexanoate [5,6]. ...
This article deals with the analysis of the condensates which are formed from fermentation gases during the fermentation of grape must. The experiment was divided into two parts. In the first part, the evolution of the individual volatiles was monitored throughout the whole fermentation process of the Riesling variety. In the second part, the condensates from three different grape varieties (Riesling, Merlot, Sauvignon blanc) were investigated and the total content of the selected volatile substances was measured at the end of the fermentation. Attention was focused on the measurements using a GC-MS (gas chromatography-mass spectrometry) for the volatile substances: isoamyl alcohol, isobutyl alcohol, 1-propanol, ethyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, acetaldehyde, acetic acid, and acetoin. In addition, changes in the alcohol content of the condensate, with respect to the fermentation phase, were analysed. From the results of part 1, the quantity of the substances under investigation produced during fermentation was determined. The highest concentration of flavour compounds was during the fourth and fifth days of fermentation. The most dominant substance was isoamyl alcohol with a concentration of 1267 mg−1.The results of part 2 led to a comparison of the overall profile of volatiles between the varieties. The results showed that the condensates have both a high content of volatile substances and of alcohol. It was also shown that the Sauvignon blanc variant had the highest number of volatile compounds in the representation. The Merlot and Riesling variants were very similar. This product has an exceptionally high potential for further use in the wine or food industry.
... Yeasts also play a crucial role in wine aroma formation, as they produce a large number of volatile compounds from grape-derived aroma precursors [8]. Moreover, lactic bacteria strains can have a significant impact on the aromatic profile of the wine produced [9,10]. The oenological practices are also important for the formation and preservation of wine aroma, i.e., storage temperatures are critical for maintaining the wine aroma that has been formed. ...
Wine exerts a fundamental influence on the global market, and its aroma remains a crucial attribute contributing to its commercial value. The market could benefit significantly if a simple and cheap method of analyzing a wine’s aromatic profile were developed. The purpose of this study is to develop such a method. A multi-analytical method for quantifying 39 volatile compounds of wine aroma was developed and validated using liquid–liquid extraction and gas chromatography/mass spectrometry/mass spectrometry (GC-MS/MS). The method was validated for its linearity, reproducibility, recovery, limit of detection, and limit of quantification and showed excellent results for almost all compounds. The method was applied to 25 commercial Protected Designation of Origin “Nemea” wines, and the results were compared and correlated with the sensory analysis results by a trained panel. The correlations among the parameters indicated that the newly developed GC-MS/MS method produces similar results to human responses.
... In this study, the higher alcohol levels in wines were all less than 300 mg/L, which would not have a negative impact on the aroma of wines [47] . High isoamyl alcohol concentration in wine did not differ among treatments, likely owing to mild water stress on Cabernet Sauvignon vines, similar to the findings in other grape varieties [48] . In contrast, other subtle higher alcohols, such as phenethyl alcohol (OAV>1), a compound that can give wine a rose fragrance, are obviously affected by irrigation [49] . ...
... Table 4 details the volatile profile of wines at the end of fermentation, revealing β-phenylethyl acetate as the primary compound affected by H. vineae. This compound that emanates a distinct fragrance reminiscent of roses [38] can enhance yeast-derived scents in wines and differentiate them from the fruity aromas typically associated with S. cerevisiae fermentations. The different time span mixed inoculations increased the concentration of β-phenylethyl acetate from 8-(S.200) up to 12-fold (S.24) compared with S. cerevisiae. ...
Hanseniaspora vineae (Hv) is a non-Saccharomyces yeast with unique metabolic features, making it appealing for wine production. However, Hv presents high nutritional requirements that may lead to slow fermentation. This study investigated the impact of sequential inoculation of Saccharomyces cerevisiae (Sc) in white winemaking at different time points (24, 48, 74, 100 and 200 h) during Hv fermentation and compared them to simultaneous inoculations. The 200 h protocol extended fermentation by an average of 13 days compared to pure Sc, decreasing with earlier sequential inoculation. Sc wines were richer in isoamyl acetate and ethyl hexanoate than Hv wines, with no significant differences among inoculation protocols. β-phenylethyl acetate was increased in Hv wines, particularly in the 24 h protocol. The 2-phenylethanol concentration was negatively correlated with the S. cerevisiae inoculation delay. Hv altered the wine aroma features, enhancing the compounds associated with rose-like scents. Reducing the Sc inoculation delay aligned Hv with industrial standards while maintaining increased β-phenylethyl acetate production. However, co-inoculation with Sc seems to better meet the Hv requirement without sacrificing the main aromatic features of Hv, demonstrating faster sugar depletion and higher acetate and ethyl ester contents, suggesting that co-inoculation yields a more modulable wine aroma profile.
... Compositional data are data carrying relative information [5], presented as proportions or percentages, making them different from other types of data. Compositional data are encountered in various fields, including biology [380], [418], [446], chemistry [2], [124], ecology [205], [429], geology [58], [87], and social sciences [116], [434], [435], among others. However, the class imbalance problem in compositional data regression remains a major challenge in the development of effective models. ...
The ongoing crisis of climate change necessitates the development of effective methods for monitoring and mapping environmental features and species to ensure their preservation. This thesis explores the application of machine learning algorithms to efficiently map coral reefs using multispectral satellite images. The Maupiti lagoon in French Polynesia serves as a case study. The research led to the production of an automated tool capable of generating coral reef maps from satellite images. Moreover, the tool can be adapted to map other ecosystems, such as forests or ice sheets, provided that the model is retrained with relevant data.
To begin, a comprehensive literature review investigates current methods and trends in utilizing machine learning algorithms for coral reef mapping. Then, the attempts to develop the tool led us to face the special case of compositional data, which are data carrying relative information and lying in a mathematical space known as simplex. Adaptations of conventional methods are required to address the specific characteristics of this space.
First, in response to data imbalance, an oversampling technique is developed specifically for compositional data. Additionally, a spatial autoregressive model based on the Dirichlet distribution is formulated to account for spatial effects that may arise in the mapping process.
Finally, we present the implementation of our final mapping tool. To achieve the desired objective, a two-staged classification process is implemented, combining pixel-based and object-based approaches. This technique enables the tool to achieve an accuracy exceeding 85% with 15 classes.
The research contributes novel solutions for handling compositional data and delivers a high-performing mapping tool for coral reef ecosystems, aiding in environmental management and conservation efforts.
... For instance, SO 2 is known to influence yeast metabolism, interfering with glycolysis and phosphorylation (Maier, Hinze, & Leuschel, 1986), affecting amino acid consumption and volatile compound formation (Garde-Cerdán & Ancín-Azpilicueta, 2007;Ribereau-Gayon, Dudourdieu, Doneche, & Lonvaud, 2006). Sulfur volatile compounds, such as hydrogen sulfide, methanethiol, and dimethyl sulfide, lead to undesirable reductive and mercaptan odours in faulty wines (Francis & Newton, 2005;Park, 2008;Siebert, Solomon, Pollnitz, & Jeffery, 2010). Meanwhile, excess SO 2 leaves an undesirable flavour and a burning sensation on the nose. ...
This study examines the feasibility of replacing SO2 in a New Zealand Sauvignon Blanc wine with a green tea extract. The treatments included the control with no preservatives (C), the addition of green tea extract at 0.1 and 0.2 g/L (T1 and T2), and an SO2 treatment at 50 mg/L (T3). Five monomeric phenolic compounds were detected in the green tea extract used for the experiment, and their concentrations ranged in the order (−)-epigallocatechin gallate > (−)-epigallocatechin > (−)-epicatechin > (−)-epicatechin gallate > gallic acid. At the studied addition rates, these green tea-derived phenolic compounds contributed to ~70% of the antioxidant capacity (ABTS), ~71% of the total phenolic index (TPI), and ~ 84% of tannin concentration (MCPT) of the extract dissolved in a model wine solution. Among wine treatments, T1 and T2 significantly increased the wine's colour absorbance at 420 nm, MCPT, gallic acid and total monomeric phenolic content. TPI and ABTS were significantly higher in wines with preservatives (i.e., T2 > T1 ≅ T3 > C, p < 0.05). These variations were observed both two weeks after the treatments and again after five months of wine aging. Additionally, an accelerated browning test and a quantitative sensory analysis of wine colour and mouthfeel attributes were performed after 5 months of wine aging. When exposed to excessive oxygen and high temperature (50 °C), T1 and T2 exhibited ~29% and 24% higher browning capacity than the control, whereas T3 reduced the wine's browning capacity by ~20%. Nonetheless, the results from sensory analysis did not show significant variations between the treatments. Thus, using green tea extract to replace at wine bottling appears to be a viable option, without inducing a negative impact on the perceptible colour and mouthfeel attributes of Sauvignon Blanc wine.
... The fraction of higher alcohols is mainly represented by 3-methyl-1-butanol (isoamyl alcohol), which has the highest amount in wines of all variants: from 85.21 mg/dm 3 -30/2 to 110.26 mg/dm 3 -30/3 and 62.10 mg/dm 3 -Syrah clone 174, and 83.33 mg/dm 3 -Sangiovese. Its characteristic aroma of malt and whiskey has been found in other studies that confirm its importance as a volatile component in the studied wines (Francis & Newton, 2005;Meng et al., 2011;Gurbuz et al., 2006). In the wines of all hybrid forms and varieties, 2-methyl-1-butanol (active amyl alcohol) has been identified, which is second in quantitative presence from the fraction of higher alcohols. ...
A comparative technological study of wines from four seedless coloured hybrid vine forms-30/2, 30/3, 30/10, 31/9 and the varieties-Syrah clone 174, Sangiovese, Marselan and Regent. It was found that on the content of trans-resveratrol, quercetin and antioxidant activity of wine, all studied hybrid forms are superior to Sangiovese and inferior to Syrah-clone 174. With a high degree of balance and stability of environmental conditions of the varieties are Syrah-clone 174, Marselan and Regent, and of the hybrid forms-30/10 and 30/2. Various representatives of the volatile aromatic composition have been identified in the studied wines, belonging to the groups of higher alcohols, esters and terpenes, acetaldehyde and methanol. The total quantitative presence of volatile compounds is higher in the wines of the hybrid forms compared to those of the control varieties. The content of sugars and acids in grapes, and alcohol and sugars in wine in hybrid forms and varieties does not differ significantly. The amounts of extract, titratable acids, anthocyanins are higher in hybrid forms. The highest amount of total phenols is observed in the wine of 30/10-3295.66 mg/dm 3 , and the lowest in Sangiovese-2060.91 mg/dm 3. With the highest organoleptic evaluation is the wine from Syrah clone 174-86.0, and from the seedless coloured hybrid forms are 30/10-83.0 and 30/3-80.0. It is possible through staged sexual hybridization to create seedless coloured varieties suitable for the production of quality wines, characterized by high taste characteristics, nutritional and medicinal value.
... The volatile compounds belonging to this first cluster included benzaldehyde, which is responsible of bitter almond-like notes [77], methyl-2-furoate (fruity notes) [78], ethyl-2furoate (balsamic notes) [79] and α-terpineol (sweet, floral notes) [80]. These compounds, despite having an OAV < 1, could contribute to the wine aroma through an additive effect with other similar compounds [81]. The second and third cluster contained 10 alcohols, 1 aldehyde, 4 esters and 1 terpene. ...
Ageing wine in barrels is an historical practice used to improve the aromatic complexity of wine, but due to the high cost and the long ageing period, alternative approaches have been developed, such as the use of wood chips and ultrasound treatment. The present paper reports the results of an investigation performed on wine (cv. Primitivo). Three treatments were investigated: a) control wine untreated; b) wine with toasted vine-shoot chips (10 g/L); c) wine with toasted vine-shoot chips (10 g/L) and treated by ultrasound. Wines were analysed after 7, 14, 21, and 28 days. The application of ultrasound combined with vine-shoot chips promoted tannin evolution, thereby accelerating the ageing process of wine. The chips addition decreased the total anthocyanins content and increased the stilbenes (trans-resveratrol and trans-piceid) and wood-related aromas (i.e., furfural, 5-methylfurfural) concentration. Finally, wines added with chips were richer in woody, vanilla, oak, and chocolate notes and more preferred by the tasters.
... Table 2 presents changes in the odour activity values (OAVs) of the volatile compounds in wines aged at 1.5 and 3 months with chips, staves, and barrels. The OAVs were calculated by dividing the concentration of each volatile compound by its respective detection threshold [64]. The OAV is another indicator that can determine the intensity of a certain substance's aroma contribution. ...
Traditionally and alternatively aged wines' odour activity values (OAVs) are investigated to differentiate and highlight the differences between the selected methods. An analysis of the volatile aroma compounds of wines derived from ageing in barrels, oak chips, and staves was performed using stir bar sorptive extraction chromatography-mass spectroscopy (SBSE-GC-MS). The results showed that alcohols, esters, and oak compounds were the main contributors to aroma, and their OAVs were higher in the stave samples after 3 months than in the samples from the other two systems of ageing. Furthermore, wines aged with staves have stronger fruity, spiced, and woody aromas, while samples aged in barrels present more chemistry-driven, floral, caramelly, and creamy aromas. The staves-medium plus toast (SMPT at 3 months > 225) and chips-medium plus toast (CMPT at 3 months > 170) showed the highest levels of aromatic series, suggesting that alternative systems provided more powerful aromas than traditional systems, such as barrels-medium plus toast (BMPT at 3 months > 150). A principal component analysis (PCA), orthogonal partial least squares (OPLS) analysis, and cluster analysis allowed for a clear differentiation to be made between red wines according to ageing systems and ageing times. The odour activity values fingerprint in winemaking is a feasible approach to characterise and distinguish wines. Moreover, OAVs provide important information on the effects of production methods on wine quality and aroma profile.
... These aromas can be perceived as very distinctive for some varietal wines. However, the volatile aroma compositions of most wines with different aromas may differ only in the proportions of these compounds (Francis & Newton, 2005). The previous studies using GC-O indicated that the characteristic aromas of icewine were likely to be formed by sensory interaction among various aroma compounds rather than an individual compound (Bowen & Reynolds, 2012;Ma, et al., 2017;Lan et al., 2019). ...
... The Odor Activity Values (OAVs) were determined to evaluate the contribution of a chemical compound to the wine aroma, providing the importance of a specific component to the sample odor. OAVs were calculated as the ratio between the individual compound concentration and the perception threshold found in literature [13,14]. A possible contribution to the aroma of wine was considered when OAV was higher than 0.1. ...
This chapter synthetizes the main results that our research group has obtained about the specific influence of a commercial Saccharomyces cerevisiae strain on the aromatic profile of fermented musts from four minority grape varieties (Vitis vinifera L.) cultivated in Castilla-La Mancha (Spain), that is, Moribel, Tinto Fragoso, Albillo Dorado and Montonera del Casar. In addition, wines made from the grape cultivars Tempranillo and Airén were evaluated. To determine the main yeast-derived odor relevant in these grape varieties, the aromatic profiles of grape cultivars and the resulting wines were studied by gas chromatography coupled to mass spectrometry and wines were subjected to Napping, a rapid sensory evaluation method. The results revealed wine sensory differences which are consequence of different aromatic profiles of wines produced with these grape cultivars. The combination of quantitative chemical analysis of volatile compounds together with sensory analysis of wines point out different patterns of aroma compound formation and release. Thus, the yeast strain used in the fermentation step is one of the main factors that affect the sensory properties of wines.
... Our data for 3-methyl-1-butanol were also in line with the results of Gil et al. (2006), who found it in the rate of 200.00 mg/l in Spanish young white wines. It was supposed that the aroma given to wine by this compound was of malt, whisky and fruit (Francis & Newton, 2005;Gil et al., 2006;Selli et al., 2004). ...
A study of the technological characteristic of Kokorko white wines was carried out. The object of the study were wines
from two consecutive vintages (2019 and 2020), obtained from two growing regions. They were produced in the Experimental
Wine Cellar of Agricultural University (AU) – Plovdiv (2019 and 2020), and the Yalovo Winery – Veliko Tarnovo (2019). The
laboratory analyzes were performed at the Institute of Viticulture and Enology – Pleven. The results showed that the samples
from AU – Plovdiv had higher alcohol content, total and sugar-free extract. The determined low titratable acidity was typical
for the variety. A correlation was found between the content of the analyzed phenolic compounds and the antioxidant activity of
the wines. Their amounts increased in the order: Kokorko, 2019 (Yalovo Winery) < Kokorko, 2020 (AU – Plovdiv) < Kokorko,
2019 (AU–Plovdiv).
A diverse volatile composition was identified in the studied wines, consisting of 17 compounds (1 aldehyde, 4 higher alcohols, 8 esters, 3 terpenes and methyl alcohol). The wine from the Yalovo Winery had the highest total volatile content. The
highest total concentration of higher alcohols was found in the sample, 2020 vintage. The main identified representatives were
2-methyl-1-butanol, 3-methyl-1-butanol, 1-propanol and 1-butanol. The wine from the Yalovo Winery contained the most
acetaldehyde and a total amount of esters. The least esters were found in Kokorko, 2020 vintage. The main representatives of
the ester fraction identified in all wines were ethyl acetate and isopropyl acetate. Propyl acetate, isopropyl acetate, butyl acetate
and isobutyl acetate were also identified. The terpenes α-terpineol, nerol and geraniol were found, as the latter had the highest
content. Methyl alcohol was present in all wines in quantities that meet the safety criteria of the drink. Kokorko wines, made
in AU – Plovdiv, had better organoleptic features in terms of aromatic and taste properties.
... Table 1 shows the concentration of individual volatile compounds and volatile families of Viura wines treated with the PS extracts and CM after one month (T1) and twelve months (T12) of bottling. Table 2 shows the OAV values, odor thresholds, and descriptors [26][27][28][29][30] of the volatile compounds with OAV > 0.2. Twenty-nine volatile compounds were detected and organized into seven different chemical families: higher alcohols, with 1-propanol, isobutanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-phenylethyl alcohol; C6 alcohols, represented by 1-hexanol, E-3-hexen-1-ol, Z-3-hexen-1-ol, and benzyl alcohol; ethyl esters, with ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl-2-methylbutyrate, ethyl isovalerate, and ethyl lactate; acetates, comprising propyl acetate, isobutyl acetate, isoamyl acetate, hexyl acetate, and β-phenethyl acetate; volatile acids, represented by isovaleric acid, hexanoic acid, octanoic acid, and decanoic acid; phenol volatiles, comprising 4-vinylguaicol and 4-vinylphenol; terpenes, formed by linalool and α-terpineol. ...
Many authors have investigated the role of mannoproteins on wine quality, but very few have analyzed the use of grape-derived polysaccharides as they are not commercially available. In this study, purified grape-derived polysaccharides from red wine (WPP) and winemaking by-products (DWRP: Distilled Washing Residues Polysaccharides) were used as potential fining agents to modulate white wine flavor. Phenolics and volatile compounds were analyzed in the control and wines treated with WPP, DWRP, and commercial mannoproteins (CMs) after one and twelve months of bottling, and a sensory analysis was conducted. WPP and DWRP, rich in rhamnogalacturonans-II, showed themselves to be good modulators of wine aroma and astringency. Improvement in wine aroma was related to an increase in all volatile families expect higher alcohols and volatile acids. The modulation of astringency and bitterness was related to a reduction in the proanthocyanidin content and its mean degree of polymerization. Extracts with polysaccharides with higher protein contents presented a higher retention of volatile compounds, and DWRP extract had more positive effects on the overall aroma. Our novel results present the possibility of obtaining valuable polysaccharides from distilled washing residues of wine pomaces, which could promote its valorization as a by-product. This is the first time the potential use of this by-product has been described.
... Compositional data are data carrying relative information [12], presented as proportions or percentages, making them different from other types of data. Compositional data are encountered in various fields, including biology [13][14][15], chemistry [16,17], ecology [18,19], geology [20,21], and social sciences [22][23][24], among others. However, the class imbalance problem in compositional data regression remains a major challenge in the development of effective models. ...
Compositional data are a special kind of data, represented as a proportion carrying relative information. Although this type of data is widely spread, no solution exists to deal with the cases where the classes are not well balanced. After describing compositional data imbalance, this paper proposes an adaptation of the original Synthetic Minority Oversampling TEchnique (SMOTE) to deal with compositional data imbalance. The new approach, called SMOTE for Compositional Data (SMOTE-CD), generates synthetic examples by computing a linear combination of selected existing data points, using compositional data operations. The performance of the SMOTE-CD is tested with three different regressors (Gradient Boosting tree, Neural Networks, Dirichlet regressor) applied to two real datasets and to synthetic generated data, and the performance is evaluated using accuracy, cross-entropy, F1-score, R2 score and RMSE. The results show improvements across all metrics, but the impact of oversampling on performance varies depending on the model and the data. In some cases, oversampling may lead to a decrease in performance for the majority class. However, for the real data, the best performance across all models is achieved when oversampling is used. Notably, the F1-score is consistently increased with oversampling. Unlike the original technique, the performance is not improved when combining oversampling of the minority classes and undersampling of the majority class. The Python package smote-cd implements the method and is available online.
... OAVs and compound perception thresholds are problematic for determining the cause of aromas in wine, as are that the thresholds are typically determined in air, water or a simple ethanol solution, not in wine. Research has shown that the thresholds of compounds in wine are very different from those determined in simple solutions [11][12][13]. These methods also do not account for how perception changes when compounds are found in mixtures and, therefore, are not appropriate for determining the cause of aromas in complex mixtures. ...
Aromatic white wines contain monoterpenes that can alter aroma qualities based on their concentration and enantiomeric ratios. Limonene has been identified as a monoterpene that is used to differentiate monovarietal white wines. The aim of this study was to evaluate the influence of limonene on aroma perception at different enantiomeric ratios. Its interaction with linalool and α-terpineol compounds was also investigated. Eighteen model wines were created with different ratios and/or concentrations of limonene and diverse concentrations of linalool and α-terpineol. Triangle tests, check-all-that-apply (CATA) and descriptive analysis were used to evaluate the aroma of the wines. Results show that different limonene ratios had no influence on wine aroma. Descriptive analysis showed that the addition of only limonene influenced citrus characteristics depending on the concentration. Linalool addition did not alter aroma quality when the limonene was at low concentrations, but it did change aroma perception at high limonene levels. α-Terpineol only altered the aroma of the wine at medium and high concentrations. At high concentrations, linalool and α-terpineol presented tropical aromas with some floral notes, irrespective of limonene levels. Depending on the desired aroma qualities of the wine, altering the monoterpene content resulted in very different aromatic wines.
... The most abundant and representative family of fermentative aromas are esters. These compounds present aromatic descriptors related to fruits and flowers [28][29][30]), giving the wines fresh and fruity notes. As observed in Table 2, the total content of esters did not present significant differences between wines. ...
The use of indigenous yeasts for the production of wines is a tool to defend the typicity of a particular region. The selection of appropriate indigenous yeasts ensures the maintenance of oenological characteristics by simulating spontaneous alcoholic fermentation (AF) while avoiding the risks of stuck or sluggish fermentations. In this study, autochthonous yeasts from Verdejo grape juice (Appellation of Origin Rueda) were selected, identified, and characterized to exploit the characteristics of the ‘terroir’. The fermentation capacity of seven strains was studied individually at the laboratory scale. The most suitable strains (Saccharomyces cerevisiae: Sacch 1, Sacch 2, Sacch 4, and Sacch 6) and Sacch 6 co-inoculated with Metschnikowia pulcherrima were characterized at the pilot scale. The fermentation kinetics, bioproduct release, volatile composition, and sensory profile of the wines were evaluated. Significant differences were found, especially in the aroma profile. In particular, Sacch 6 and Sacch 6 co-inoculated with M. pulcherrima produced higher amounts of ethyl esters and acetates and lower amounts of higher alcohols than the spontaneous AF. Wines inoculated with indigenous yeasts had higher sensory scores for fruit aromas and overall rating. The selection of indigenous yeasts improved the aroma of Verdejo wines and could contribute to determining the wine typicity of the wine region.
... Out of the seven identified acids, notable ones included acetic acid in SS1, SS2 and P1 corks, hexanoic and octanoic acids in SS1 and SS2 corks, and 2-ethylhexanoic acid in P1 corks. These acids are typically present in the volatile fraction of wines, but due to their high thresholds, their negative olfactory notes do not significantly contribute to wine aroma [29]. Acetic acid was the major acid identified, which could have originated from thermal procedures used during the processing of cork planks and stoppers. ...
Natural cork remains a favored option for sealing high-quality wine bottles, despite its high cost for wineries. The cork industry faces the challenge of certifying the quality and traceability of these corks, with physical–chemical characterization being a valuable tool in establishing these parameters. While cork taint compounds must be absent or in low concentrations, the volatile fraction of cork contains numerous compounds that, even in small amounts, can impact the wine’s final aroma. Moreover, these volatile compounds are indicative of the geographical origin of the cork planks used to make the stoppers. In this work, a total of 68 volatile compounds (alkanes, terpenes, benzenic compounds, aldehydes, ketones, acids, esters, alcohols and furanic and pyranic compounds) from natural corks of different qualities and origins were identified, using a fast and sensitive technique: headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME-GC-MS). Based on these volatile compounds, it was possible to establish differences between corks of different origins, although no discernible differences were detected in the samples of differing visual qualities, as this is a subjective parameter largely dependent on the cork’s external appearance. These findings show that the analysis of the volatile composition of corks via HS-SPME-GC-MS can be used as a quick tool for tracking their traceability and selecting the most appropriate parameters at each stage of processing to minimize the increase in unwanted compounds.
... OAVs were calculated by dividing the concentration of the compounds by their sensory thresholds [24,26,27]. If the compounds were present at above-threshold levels (OAV > 1), these compounds were recognized to have the potential to actively contribute to the aroma of the wines [28,29]. ...
... Scientific studies have embarked on identifying the various substances in wine grapes that shape the scent of the produced wines. A future goal is to develop specific strategies to identify the taste of wines in terms of consumer expectations [36]. ...
... These concentrations were higher than those measured by Lorenzini et al. [11], suggesting that the Topaz apple cultivar contains higher amounts of glycosidic precursors. However, the linalool concentrations are very low and far below the odour thresholds [42]; therefore, no significant contribution to the overall aroma can be assumed. ß-damascenone, which contributes to a fruity aroma described as stewed apple and quince paste, was quantified in 1.87 (±0.01) and 1.55 (±0.01) µg/L for the ciders CA and CB, respectively. ...
Torulaspora delbrueckii is known for improving the aroma quality in wine and beer, but information for cider manufacturing is scarce. We explored the behaviour of two commercial strains of T. delbrueckii in apple juice fermentation to produce cider and sparkling cider. The influence of the strain, method, and strain–method interaction on the physicochemical parameters of cider was analysed by enzymatic and chromatographic assays. The data were subjected to an analysis of variance and a principal component analysis. Both strains also showed regular fermentation kinetics under pressure. Ethanol, lactic acid, acetic acid, and glycerol were produced with significant differences between strains and production methods. Then, 26 volatile compounds were identified, with higher alcohols being the quantitatively most abundant group. Strain A was associated with a higher production of methyl butanol, 2-phenyl ethanol, and butyric, propionic, and succinic acid esters, while strain B was associated with higher amounts of hexanoic acid, and acetate and valerate esters. In addition, 13 compounds showed significant differences between methods, and 14 were influenced by the method–strain interaction. Our findings encourage the further investigation of the application of T. delbrueckii as a solo player to produce ciders with a unique flavour.
... Wine is a highly complex and versatile drink, presenting a large variety of chemical compounds that derive from numerous sources during vinification [1] and play significant roles in the sensory profiles and perception of the final product. As such, over 8000 volatile compounds have been estimated to be found in wines, a significant number of those resulting from fermentation processes [2,3]. ...
Vitamins are major cofactors to numerous key metabolic pathways in enological yeasts, and both thiamine and biotin, notably, are believed to be essential to yeast fermentation and growth, respectively. In order to further assess and clarify their role in winemaking, and in the resulting wine, alcoholic fermentations of a commercial Saccharomyces cerevisiae active dried yeast were conducted in synthetic media containing various concentrations of both vitamins. Growth and fermentation kinetics were monitored and proved the essential character of biotin in yeast growth, and of thiamine in fermentation. The synthetic wine volatile compounds were quantified, and notable influences of both vitamins appeared, through a striking positive effect of thiamine on the production of higher alcohols, and of biotin on fatty acids. Beyond the evidence of this influence on fermentations and on the production of volatiles, this work proves, for the first time, the impact held by vitamins on wine yeasts’ exometabolome, investigated through an untargeted metabolomic analysis. This highlighted chemical differences in the composition of synthetic wines through a notably marked influence of thiamine on 46 named S. cerevisiae metabolic pathways, and especially in amino acid-associated metabolic pathways. This provides, overall, the first evidence of the impact held by both vitamins on the wine.
... The fruits chemical composition affects the sensory characteristics of the juice. According to Francis and Newton [62], aroma results from interactions of numerous chemical compounds. The cultivar [63][64][65], agricultural practices (conventional vs. biological) [66,67], post-harvest treatments, www.videleaf.com ...
The current consumer, with privileged access to information, can make more responsible and demanding choices, preferring healthy and environmentally friendly products. The food industry also takes advantage of technological and scientific advances to produce food and drinks that better adapt to consumer demand, with more sustainable and efficient production processes. The composition and functional and nutritional properties of fruit juice and fermented fruit drinks justify the development of various studies due to their proven effectiveness in the prevention of cardiovascular, cancer, and neurodegenerative diseases, among others. Non-thermal food processing has been highlighted in recent years and different emerging technologies are under study to evaluate their potential as an alternative to conventional heat treatments. The use of non-thermal processes minimizes undesirable changes in the food because involve methods by which fruit juices receive microbiological inactivation and enzymatic denaturation with or without the direct application of low heat, thereby lessening the adverse effects on the nutritional, bioactive, and flavor compounds of the treated fruit juices, extending their shelf-life.
... The volatile profile is influenced by ripeness, grape variety, geographical factors (climate and soil), wine-making practices (pH, temperature, and yeast activity in fermentation and aging conditions), oxidation, and wine defects [2][3][4]. Knowledge of the aroma composition is, therefore, an important source of information on wine quality and can be useful for the prediction of sensory properties [5,6], for geographical or varietal discrimination [7][8][9], and to guide the setup of production technologies aimed at exalting one or more aromas in the final wines [10][11][12]. ...
Headspace Solid-Phase Microextraction coupled to Gas-Chromatography with Mass Spectrometry detection (HS-SPME/GC-MS) has been widely used to analyze the composition of wine aroma. This technique was here applied to investigate the volatile profile of Trebbiano d'Abruzzo and Pecorino white wines produced in Abruzzo (Italy). Optimization of SPME conditions was conducted by Design of Experiments combined with Response Surface Methodology. We investigated the influence of the kind of sorbent, PDMS, CW/DVB, or PDMS/CAR/DVB, and the effect of the fiber exposure time, temperature, and salt concentration on the total area of the chromatogram and the extraction efficiency of ethyl decanoate and 3-methyl-1-butanol, representative of apolar and polar compounds, respectively. The PDMS/CAR/DVB sorbent allowed the extraction of about 70 compounds, whereas only a part of these substances could be extracted on the PDMS and CW/DVB fibers. Reliable response surfaces for the total area and peak areas of the selected volatiles collected on the PDMS and PDMS/CAR/DVB sorbents and, in the latter case, principal component analysis were evaluated to find the optimal conditions. The optimized extraction conditions were applied for a preliminary comparison of the volatile profile of the two wine varieties and in a successive varietal discrimination study based on data-fusion approaches.
To delay the grape ripening period to a cooler season, the possibility of applying cultivation techniques that utilize lateral shoots, which grow after young shoot cutting between the fifth and sixth nodes and simultaneous flower cluster removal, were tested in six varieties of Vitis vinifera grapevines（‘Chardonnay’, ‘Riesling’, ‘Semillon’, ‘Pinot Gris’, ‘Pinot Noir’, and ‘Syrah’）. Flowering, veraison or coloration, and harvest events in the varieties of treated grapevines occurred approximately one month later than in untreated control grapevines, and the mean maximum and minimum air temperatures during ripening periods were respectively 3.6-5.6 and 1.3-6.8 ℃ lower than those in the controls. Lower air temperature during the ripening period in treated grapevines positively affected skin anthocyanin content, malic acid content, and juice pH, as well as the color intensity of ‘Syrah’ red wine and the linalool content of ‘Riesling’ white wine. The cultivation techniques that utilize lateral shoots can be widely applied to V. vinifera, and are expected to be effective to improve fruit quality in warm regions.
Over the past few decades, there has been a notable paradigm shift worldwide, affecting people’s preferences and decisions regarding both food and beverage options. These factors have sparked a newfound fascination among winemakers, wine enthusiasts, and consumers alike, as they explore the notion of reconnecting with a bygone era and embracing a lifestyle reminiscent of the past. “Orange” wine, a product derived from white grapes, encapsulates the intriguing allure of ancient winemaking methods that trace their roots back to Georgia. The method enables an elevated presence of phenolic compounds, which can have a favorable influence on the sensory characteristics of the wines or their behavior during oxidative processes. Given the scarcity of widespread knowledge, this overview aims to provide a comprehensive understanding of the historical evolution of winemaking and its various transformations over the years. It delves into the intricacies of winemaking technology, particularly focusing on the unique utilization of qvevri vessels. In addition to traditional sources, this review examines the influence of winemaking technology and the utilization of special vessels on the characteristics of “orange” wines. It explores the unique traits that develop in these wines as a result of prolonged maceration. By considering the impact of these factors, the review offers insights into the distinct qualities and attributes that emerge in “orange” wines during the winemaking process.
Wine flavor is a vital quality characteristic in wine, influenced by those flavor components with low sensory thresholds. It is crucial to recognize and classify the wine components related to their flavor contribution. The integration of fluorescent sensors and artificial intelligence shows huge potential in flavor recognition by emulation of the gustatory perception system. Meanwhile, achieving information identification of wine based on multiple information barcodes has hopeful applications in anticounterfeiting. In this study, we present a simple method in which organic linkers are weaved into a hydrogen-bonded organic framework (HOF) for the available transformation of a metal-bonded organic framework (MOF) induced by lanthanide ions (Ln3+). The fluorescent Ln-MOF/HOF composite exhibits high sensitivity, rapid response, and good recyclability for detecting seven flavor compounds in wine, including tannic acid, ionone, vanillin, anethole, anisaldehyde, hydroxybenzaldehyde, and 4-hydroxy-2-methylacetophenone. Depending on its satisfactory detectability, a novel strategy is provided in which a fluorescent sensor is able to function as a smart fluorescent-tongue (F-tongue) by the aid of convolutional neural network to differentiate these seven flavor compounds. In addition, the Ln-MOF/HOF composite has been used to prepare multiple information barcodes for wine information identification on the basis of dynamic fluorescence response toward tannic acid. The mimetic gustatory perception system developed in this study may offer a promising strategy for flavor recognition in food and further food anticounterfeiting.
This study investigated the effect of controlled oxygen addition during alcoholic fermentation (4 mg/L, at 2nd, 4th, 6th, 10th, 14th, 16th, 20th day) and aging on lees (2 mg/L, every 15 days for 3 months) in a stainless-steel tank for white wine production from a nearly neutral grape. Under less reductive conditions (Ox), alcoholic fermentation was completed in 27 days, whereas one extra week was required under more reductive conditions (no-Ox). The greatest amount of dissolved oxygen in Ox wine triggered the increase of redox potential (EH) starting from the end of alcoholic fermentation and throughout aging (169 and 150 mV in Ox and no-Ox wine, respectively), also improving the wine resistance to browning. Oxygen addition from the early stages of winemaking significantly modulated volatile composition and sensory attributes, which may contribute to the diversification of wine style.
Aroma is an important aspect of wine quality and consumer appreciation. The volatile organic compounds (VOCs) and olfactory profiles of Merlot dry red wines from the Eastern Foothill of Helan Mountain (EFHM) were analyzed using gas chromatography-mass spectrometry and quantitative descriptive analysis. The results showed that Merlot wines from EFHM were characterized by intense flavors of drupe and tropical fruits compared with the Gansu region. Nineteen VOCs were defined as essential compounds contributing to the aroma characteristics of the Merlot wines through gas chromatography–olfactometry/mass spectrometry and odor activity value analysis. Predominantly, geranyl isovalerate, which contributed to the herbal odors of the Merlot wines, was detected in the grape wine of EFHM for the first time. The addition experiment revealed that geranyl isovalerate influenced the aroma quality of wine by increasing herbal odors and enhancing the olfactory intensities of tropical fruits. These results are helpful for further understanding the aroma of Merlot wines from EFHM and improving the quality of wine aromas.
Despite Xinomavro (Vitis vinifera L.) being a well-known noble red grape variety of northern Greece, little is known about its ''bouquet'' typicity. Volatile compounds of Xinomavro wines produced using a common vinification protocol were analyzed by gas chromatography-mass spectrometry and sensory descriptive analysis was carried out with a trained panel. Wines were characterized by the presence of fatty acids, ethyl and acetate esters, and alcohols, with contributions from terpenes and a volatile phenol. The most active aroma compounds were determined to be 3-methylbutyl acetate, β-damascenone, ethyl esters of octanoic and hexanoic acids, and eugenol. Those compounds positively correlated with fruity and spicy odor descriptors, with the wines being mostly characterized by five typical aroma terms: strawberry, berry fruit, spices, tomato, and green bell pepper. Partial least squares regression (PLSR) analysis was used to visualize relationship between the orthonasal sensory attributes and the volatile aroma compounds with calculated OAVs > 1. Key aroma-active volatiles in the wines were identified using GC-MS/olfactometry, providing a list of 40 compounds, among which 13 presented a modified detection frequency > 70%. This study is the first of its kind and provided strong indications regarding the aroma compounds defining the sensory characteristics of Xinomavro wines.
Cantonese-style rice vinegar is one of the most important Chinese rice vinegars and is quite popular all over the southeast coast of China, especially in Guangdong. This study identified 31 volatile compounds, including 11 esters, 6 alcohols, 3 aldehydes, 3 acids, 2 ketones, 1 phenol, and 5 alkanes, using headspace solid-phase microextraction-gas chromatography-mass spectrometry. Six organic acids were detected by high performance liquid chromatography. The ethanol content was detected by gas chromatography. During acetic acid fermentation, physicochemical analysis showed that the initial concentrations of reducing sugar and ethanol were 0.0079 g/L and 23.81 g/L, respectively, and the final value of total acid was 46.5 g/L, and the pH value was stable at 3.89. High-throughput sequencing was used to identify the microorganisms, and Acetobacter, Komagataeibacter, and Ralstonia were the top three bacterial genera. Quantitative real-time polymerase chain reaction revealed patterns that were different from those of high-throughput sequencing. The co-occurrence network of microorganisms and the correlation analysis between microorganisms and flavor substances indicate that Acetobacter and Ameyamaea played crucial roles as the main functional AAB, and the failure of Cantonese-style rice vinegar fermentation can be attributed to the abnormal increase in Komagataeibacter. Microbial co-occurrence network analysis indicated that Oscillibacter, Parasutterella, and Alistipes were the top three microorganisms. Redundancy analysis disclosed that total acid and ethanol were the key environmental factors influencing the microbial community. Fifteen microorganisms closely related to the metabolites were identified using the bidirectional orthogonal partial least squares model. Correlation analysis showed that these microorganisms were strongly associated with flavor metabolites and environmental factors. The findings of this study deepen our understanding of the fermentation of traditional Cantonese-style rice vinegar.
Mixed fermentation using saccharomyces cerevisiae and non-saccharomyces cerevisiae has become one of the main research strategies to improve wine aroma. Hence, this study applied the mixed fermentation technique using Pichia kudriavzevii and Saccharomyces cerevisiae to brew Cabernet Sauvignon wine and to investigate the effects of inoculation timing and inoculation ratio on the polyphenolics, antioxidant activity and aroma of the resulting wine. The results showed that mixed fermentation significantly improved the amounts of flavan-3-ols. In particular, S1:5 had the highest amounts of (-)-catechin and procyanidin B1 (73.23 mg/L and 46.59 mg/L), while S1:10 had the highest (-)-epicatechin content (57.95 mg/L). Meanwhile, S1:10 showed the strongest FRAP, CUPRAC and ABTS + activities (31.46 %, 25.38 % and 13.87 % higher than that of CK, respectively). In addition, mixed fermentation also increased the amounts of phenylethanol, isoamyl alcohol and ethyl esters, which enhanced the rose-like and fruity flavor of wine. This work used a friendly non-saccharomyces cerevisiae alongside appropriate inoculation strategies to provide an alternative approach for improved wine aroma and phenolic profile.
Wine is a highly complex mixture of components with different chemical natures. These components largely define wine's appearance, aroma, taste, and mouthfeel properties. Among them, aroma is among the most important indicators of wine's sensory characteristics. The essence of winemaking ecosystem is the process of metabolic activities of diverse microbes including yeasts, lactic acid bacteria, and molds, which result in wines with complicated and diversified aromas. A better understanding of how these microbes affect wine's aroma is a crucial step to producing premium quality wine. This study illustrates existing knowledge on the diversity and classification of wine aroma compounds and their microbial origin. Their contributions to wine characteristics are discussed, as well. Furthermore, we review the relationship between these microbes and wine aroma characteristics. This review broadens the discussion of wine aroma compounds to include more modern microbiological concepts, and it provides relevant background and suggests new directions for future research.
L'élevage des vins en barriques modifie profondément leur expression aromatique.
L'étude par chromatographie en phase gazeuse et spectrométrie de masse permet d'identifier plusieurs substances volatiles appartenant à la fraction phénolique des arômes.
Les vins rouges présentent naturellement une composition complexe en phénols volatils alors que celle des vins blancs est plus simple. L'élevage sous bois entraîne une augmentation notable des phénols déjà présents ainsi que l'apparition de molécules spécifiques au bois dechêne brûlé.
L'interaction des levures et des bactéries avec le bois est mise en évidence.
Les vins rouges se caractérisent par une présence parfois abondante d'éthyl phénols, les vins blancs qui ne subissent pas la fermentation malolactique s'en différencient par l'abondancede vinyl phénols.
L'étude sensorielle de chaque substance permet de démontrer le rôle négligeable de certaines : furfural, méthyl-5-furfural, alcool furfurylique et le rôle exceptionnel joué par d'autres : cis et trans β-méthyl-γ-octalactone, vanilline et dans certains cas éthyl-4-phénol et éthyl-4-gaïacol.
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Wood storage of wines changes profondly their aromatic expression.
Several volatile substances from wines and oak woods phenolic fraction of aroma are identified by gas chromatography and mass spectrometry. Wood storage increases natural phenols concentration. Simultaneously specific burned wood molecules appear.
Yeast and bacterial interaction with wood is demonstrated. Ethyl phenols are characteristic of red wines and vinyl phenols of white wines without malolactic fermentation.
The sensorial analysis of each substance demonstrates the negligible intervention in wine aroma of furfural, 5-methyl-furfural, and furfuryl alcohol, and the important participation of cis and trans β-methyl-γ-octalactone, vanilin 4-ethyl-phenol and 4-ethyl gaïacol.
prefermentation practices, sensory evaluation Monoterpenes are responsible for the distinctive flavour of grape cultivars such as Gewiirztraminer, Riesling and several muscat cultivars. These components are present as odour-active free volatile terpenes (FVT) and as potentially volatile terpenes (PVT), i.e. glycosides and polyols capable of releasing FVT by temperature-, pH-, or enzyme induced hydrolysis. Our first work focused on the impact of fruit exposure on terpene concentrations in Gewiirztraminer. FUlly-exposed fruit consistently displayed higher FVT and PVT than partially-exposed and fully-shaded fruit. This knowledge was utilised to investigate effects of cultural practices. Hedging and basal leaf removal (BLR) increased FVT and PVT levels, while multi-site experiments also indicated that hedging and BLR could increase FVT and PVT in berries and musts of early-season cultivars such as Bacchus, Pearl of Csaba, Gewiirztraminer, Schonburger and Siegerrebe. Canopy division, BLR and increased vine spacing also increased FVT and PVT concentrations in Riesling fruit. Low-heat unit sites appear to promote accumulation of monoterpenes in Vitis vinifera more than warmer sites, when compared at equal growing degree days. Prefermentation practices such as delayed harvest, prolonged pressing and skin contact were also shown to increase must terpene content. In many cases, these differences in terpene concentrations in the berries and musts were organoleptically detectable in wines. Our conclusions to date are: (l) PVT are more responsive to viti cultural and enological practices than FVT; (2) FVT and PVT are rarely correlated with soluble solids, titratable acidity or pH, and thus cannot be predicted by standard harvest indices; (3) Losses in FVT and PVT can occur between the berry and juice stages, hence the desirability of skin contact; (4) FVT and PVT concentrations can, in some cases, be related to wine-tasting results.
Twenty rose and ten claret A.O.C. Bordeaux wines made from Cabernet Sauvignon, Cabernet franc and Merlot grapes were separately tasted by the same jury of ten professionals. They were asked to classify the wines according to the intensity of the fruity character. The fruitiest sample was given first rank. The wines’ bdamascenone, b-ionone, phenyl-2-ethanol, isoamyl acetate, phenyl-ethyl acetate (APE), 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (A3MH) contents were also measured. The higher the latter three compounds' values, the higher the wines’ fruity character. Highly significant correlation were found between the sensorial analysis results and these compounds contents. In order to confirm the 3MH, A3MH and APE contribution to the fruity aroma of rose wines, a tasting has been carried out. For this, these three compounds were added to a rose wine up to the concentrations found in the wine judged the fruitiest by the tasters. 100 % of the tasters identified the supplemented glasses, and 90 % prefered the supplemented wine. This second experiment clearly demonstrate that 3MH, A3MH and APE can be considered key components of Bordeaux rose wines’ fruity aroma.
The production of APE by yeast has been known for a long time. The 3MH is present in must under cysteinylated precursor form. The transformation of the precursor into aroma is made by the Saccharomyces cerevisiae yeasts during alcoholic fermentation. Thus the choice of yeast strains has a decisive impact on the fruity aroma of Bordeaux rose and claret wines.
Chancellor grapes were vinified with Saccharomyces bayanus strains RC 212 or Montrachet at 15°C and 25°C. Malolactic fermentation (MLF) in wines from each treatment was initiated post-vinification by inoculation with two commercial malolactic (ML) starter cultures (Inobacter and X3) to assess the effect of individual starters on the chemical and sensory properties of the wines. Volatile esters, aldehydes, alcohols, ketones, acids, and sulfur-containing compounds were identified and quantified by gas chromatography/mass spectrometry. Concentrations of several individual compounds were influenced by the ML cultures. Fermentation temperature, ML culture, and yeast strain, acting independently or interacting together, also influenced the development of distinct volatile compounds. In contrast, differences in the intensity of aroma and flavor attributes, when present, could only be ascribed to ML culture, yeast strain, or fermentation temperature interacting together. Higher wine color intensity and citric acid content were measured in wines fermented with ML culture X3. The development of unique or distinct aromas and flavors in Chancellor wines that have undergone MLF is a consequence of complex interactions between metabolites derived from both bacteria and yeast.
Ten strains of Saccharomyces cerevisiae (V1116, D254, UCD 522, Bourgoblanc, EC1118, UCD 595, S6U, Wadenswil 27, 71B, T73) were evaluated in terms of their impact on the chemical composition of fermenting Riesling and Chenin blanc musts and on the sensory characteristics of their resultant wines. All yeasts completely utilized glucose present. Fructose concentrations in finished wines ranged from 1.5 to 7.0 g/L and were highest in UCD 595. Glycerol concentration was highest in Bourgoblanc and lowest in T73. Ethanol production was similar among the various strains, although UCD 522 produced higher ethanol than D254. Some differences existed between the yeasts in terms of production and/or use of six organic acids (citric, tartaric, malic, succinic, lactic, and acetic). Lowest tartaric and malic acids were found in 71B fermentations, while highest acetic acid concentrations were measured in both 71B and Wadenswil 27. Wadenswil 27 fermentations also contained highest tartaric, succinic (along with Bourgoblanc), and lactic acids. Highest citric acid was found in S6U fermentations, while both S6U and V1116 contained lowest acetic acid concentrations. T73 contained highest malate and lowest citrate. Sensory evaluation of Riesling wines showed that most yeasts produced more intense aromas and flavors than those fermented with EC1118. Wadenswil 27 produced Chenin blanc wines with more aroma and flavor intensity than EC1118.
Wine aroma is very complex, and its olfactometric evaluation has to face several difficulties added to those linked to olfactometry. In the past, scientists have found many problems in the identification of the truly important odorants and huge efforts have been made in the isolation and identification of non-relevant volatile compounds. This has contributed to the idea that it is not possible to get actual — scientific and technological — advantages from the analysis of wine aroma. However, in the last 5 years most of the actually relevant aroma volatiles have been isolated and identified. What this means is that it is only now that it has become possible to evaluate the different methods and working strategies, and to design how olfactometric research should be conducted to be successful.
The possible influence of Harmonia axyridis (the Multicolored Asian Lady Beetle) on the sensory properties of wine was investigated. Harmonia axyridis were added to white and red grape musts at a rate of 0, 1, or 10/L, and a trained panel evaluated the finished wines using flavor-profiling techniques. Significant modification of both wine aroma and flavor characteristics were observed in the 10 beetle/L treatments, with smaller effects noted at the 1 beetle/L rate. Vinification in the presence of H. axyridis gave higher intensity scores for peanut, bell pepper, and asparagus aromas and flavors in the white wines and for peanut, asparagus/bell pepper, and earthy/herbaceous aromas and flavors in the red wines. In addition, sweet, acid and bitter tastes were affected in red wines, and a general trend of decreasing fruit and floral intensities with increasing beetle rate was observed in both white and red wines.
The influence of naturally occurring and added methoxypyrazines on wine aroma was assessed by sensory evaluation. Addition of 2-methoxy-3-(2-methylpropyl)pyrazine or 2-methoxy-3-(1-methylethyl)pyrazine, at 1 ng/L and 2 ng/L, respectively, significantly influenced the aroma of a methoxypyrazine-free white wine. Ranking of samples prepared by addition of 2-methoxy-3-(2-methylpropyl)pyrazine (0-32 ng/L) to the methoxypyrazine-free wine showed that the compound contributed significantly to vegetative aroma at 8 ng/L or above. A range of commercial Sauvignon blanc wines was assessed by scoring for vegetative varietal aroma intensity and methoxypyrazine aroma intensity. Comparison with the naturally occurring methoxypyrazine concentration showed that wines of high (> 26 ng/L) and low (< 12 ng/L) methoxypyrazine concentration were clearly distinguished on the basis of vegetative varietal aroma or methoxypyrazine aroma. It is concluded that methoxypyrazines do contribute to the characteristic vegetative aroma of Sauvignon blanc wines.
Food aromas generally are complex mixtures of volatiles. In the present study, we investigated the joint effects of hexyl acetate, trans-2-hexenal and 1-hexanol on the multi-attribute perception of an apple aroma. The first two substances were identified earlier as positive contributors to the apple aroma (high character impact), whereas the third component was identified as an irrelevant or negative contributor (low character impact). Aroma quality was quantified using a set of eight graphic rating scales. All three components had significant effects on the aroma profiles. These effects consist mainly of an effect of each component on the attribute that described its individual character and an effect of all three components on ratings on the main character attribute 'apple'. As expected, the high impact components increased 'apple' ratings, whereas the low character impact component decreased 'apple' ratings. Furthermore, intensity ratings on the attribute that corresponded with the odour of the low impact component were suppressed by the presence of high impact components. These results indicate that the contributions of odorants to the mixture's aroma are not linear combinations of separate odour intensities, because sensory interactions were observed. In addition, humans detect components in complex mixtures more accurately than studies on identification performance have suggested. We conclude that for an adequate assessment of the effects of multiple mixture components on changes in aroma perception, it is sufficient to employ multiple response scales measuring intensities of attributes that are distinctive with respect to the expected qualitative changes. Results of this approach should be subjected to multivariate methods of statistical analysis.
The influence of naturally occurring and added methoxypyrazines on wine aroma was assessed by sensory evaluation. Addition of 2-methoxy-3-(2-methylpropyl)pyrazine or 2-methoxy-3-(1-methylethyl)pyrazine at 1 ng/L and 2 ng/L, respectively, significantly influenced the aroma of a methoxypyrazine-free white wine. Ranking of samples prepared by addition of 2-methoxy-3-(2-methylpropyl)pyrazine (0-32 ng/L) to the methoxypyrazine-free white wine showed that the compound contributed significantly to vegetative aroma at 8 ng/L or above. A range of commercial Sauvignon blanc wines was assessed by scoring for vegetative varietal aroma intensity and methoxypyrazine aroma intensity. Comparisone with the naturally occurring methoxypyrazine concentration showed that the wines of high (>26 ng/L) and low (<12 ng/L) methoxypyrazine concentration were clearly distinguished on the basis of vegetative varietal aroma or methoxypyrazine aroma. It is concluded that methoxypyrazines do contribute to the characteristic vegetative aroma of Sauvignon blanc wines.
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 largest collection of basic, clinical, and applied knowledge on the chemical senses ever compiled in one volume, the third edition of Handbook of Olfaction and Gustation encompass recent developments in all fields of chemosensory science, particularly the most recent advances in neurobiology, neuroscience, molecular biology, and modern functional imaging techniques. Divided into five main sections, the text covers the senses of smell and taste as well as sensory integration, industrial applications, and other chemosensory systems. This is essential reading for clinicians and academic researchers interested in basic and applied chemosensory perception.
Volatile compounds released from Cabernet Sauvignon and Merlot grape glycoside fractions, isolated from both skin and juice, were studied by sensory descriptive analysis and by gas chromatography-mass spectrometry (GC-MS). Both acid- and enzyme-hydrolysates were studied. The contribution to wine aroma of the different fractions was evaluated by sensory analysis of white wines to which the hydrolysates had been added. Acid-hydrolysates from each variety increased the intensity of attributes such as tobacco, chocolate and dried fig. In contrast, glycosidase enzyme-hydrolysates gave no detectable change in aroma. The relationship among the aroma attributes of the hydrolysates and their volatile composition was investigated using partial least square regression analysis (PLS), which indicated that the intensity of the attributes dried fig, tobacco and honey could be related to the concentration of specific compounds of the norisoprenoid, benzene derivative, monoterpene and aliphatic classes. The red-free glycosyl-glucose (G-G) concentration of the skin extracts and juices was correlated with the scores of aroma attributes of the glycoside hydrolysates, suggesting the potential of the G-G assay as a predictor of wine aroma.
In Cabernet Sauvignon must, total and phenol-free glycosides (expressed as glycosyl-glucose) rose during fermentation while skin concentrations dropped. Wines were heated postfermentation, prior to dejuicing (rising 2 to 3°C per day from 23 to 42°C, and held for one day at 42°C), or after bottling (at 42°C for 21 days) to determine the effect on total glycosides, glycosidic fractions, and anthocyanin complexing. Pre-dejuicing thermal vinification resulted in higher total (12%) and phenol-free (18%) glycosides. Large polymeric pigments rose 208% and small polymeric pigments rose 41%. Skins had lower total glycosides (-16%), and no significant difference in phenol-free glycosides. Postbottling heat treatment resulted in lower total (-15%) and phenol-free (-16%) glycosides, and increased hue (25%). Large polymeric pigments increased 62% compared to control wines.
Volatile compounds released from Cabernet Sauvignon and Merlot grape glycoside fractions, isolated from both skin and juice, were studied by sensory descriptive analysis and by gas chromatographymass spectrometry (GC-MS). Both acid- and enzyme-hydrolysates were studied. The contribution to wine aroma of the different fractions was evaluated by sensory analysis of white wines to which the hydrolysates had been added. Acid-hydrolysates from each variety increased the intensity of attributes such as tobacco, chocolate and dried fig. In contrast, glycosidase enzyme-hydrolysates gave no detectable change in aroma. The relationship among the aroma attributes of the hydrolysates and their volatile composition was investigated using partial least square regression analysis (PLS), which indicated that the intensity of the attributes dried fig, tobacco and honey could be related to the concentration of specific compounds of the norisoprenoid, benzene derivative, monoterpene and aliphatic classes. The red-free glycosyl-glucose (G-G) concentration of the skin extracts and juices was correlated with the scores of aroma attributes of the glycoside hydrolysates, suggesting the potential of the G-G assay as a predictor of wine aroma.
A major stimulus to research on grape flavour has been wine production, because grape varietal flavour is a primary determinant of wine style, quality and price. This emphasis on winegrape varietal flavour contrasts with the flavour requirements of grapes destined for drying or the table market, for which the concentrations of sugars and acids are of prime importance. The flavour of dried grapes is also strongly influenced by Maillard chemistry, and because this topic has been reviewed extensively (Vernin and Párkányi 1982; Waller and Feather 1983) it will not be treated in the present work. The specific flavour attributes of table grapes have attracted little attention (Webb 1981) although floral characteristics would doubtless be appreciated and information about winegrape flavour is of relevance to this topic.
Understanding "what" consumers want and "why" are two of the most significant hurdles faced by any business creating products for consumers. Properly conducted sensory research experiments can provide answers to these questions and more. Sensory evaluation provides strategic information at various stages in the product lifecycle including the front end of innovation, new product development, product optimization, marketplace audits, and quality control among others. Sensory research can help identify issues that contribute to a product's success (or failure). This fourth edition draws on the author's practical experience in partnering with business associates in marketing and development teams to bring creativity and innovation to consumer driven product development in today's global business environment. The field of sensory science continues to grow and is now recognized as a strategic source of information for many Fortune 500 companies. Many scientists working in this field depend on the core textbooks such as this one to enhance their working knowledge base with practical business applications. * Appeals to sensory professionals in both in academia and business * Methods to integrate sensory descriptive information and consumer assessment * Coordinate marketing messages and imagery with the product's sensory experience.
The accuracy of two methods for determination of glycosyl-glucose (GG) in grapes and wine has been tested using several glycoside standards containing alkyl, benzenoid, and phenolic aglycones. The total GG method using C-18 sorbent material was found to exhibit poor recoveries of benzenoid glycosides. The recoveries for the phenol-free GG method were satisfactory for alkyl and benzenoid glycosides. In addition, an adaption of the phenol-free GG method to 96-well microplate format has been demonstrated.
The contribution that glycosidically-bound volatiles make to varietal wine aroma was determined by sensory descriptive analyses. Sensory studies were made on grape glycosides a) hydrolyzed under accelerated conditions i) in vitro and back added to wine, and ii) in situ in wine; b) hydrolyzed under conditions of natural aging. These studies confirmed the role of glycoside hydrolysis in the expression of varietal wine aroma. The sensory data have lent support to the development of a method for quantifying total glycosides in wine grapes, thus giving an indication of juice 'richness'. This assay, made through a determination of the glycosyl-glucose, offers the possibility of an objective pre-harvest measure of grape, and hence potential wine quality.
Two different white wine varieties (Gewürztraminer and Scheurebe), which differ in their odor profiles, were investigated by gas chromatographyolfactometry (GC-O). Aroma extract dilution analysis (AEDA) and static headspace analysis-olfactometry (SHA-O) yielded 41 and 45 odor-active compounds for Scheurebe and Gewürztraminer wines, respectively. An unknown compound with coconut-like and woody odor qualities, which has not yet been detected in wine or a food, was identified as (3S,3aS,7aR)-3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3H)-one (wine lactone). Quantitation and calculation of odor activity values of potent odorants showed, that differences in odor profiles of both varieties were mainly caused by cis-rose oxide in Gewürztraminer and 4-mercapto-4-methylpentan-2-one in Scheurebe. Reconstruction of the flavor and quantitation of potent odorants in the different stages of wine making of Gewürztraminer will be discussed.
Four strains of Saccharomyces cerevisiae were evaluated for their influence on White Riesling glycoconjugates. Fermentation resulted in a decrease in bound glycosides, as estimated by the analysis of glycosyl glucose. The greatest reduction occurred with the Fermiblanc strain, although the maximum difference among yeasts was only 7%. The concentration of bound monoterpene alcohols, oxides, and aromatic alcohols was diminished due to fermentation, although generally similar among yeasts. Following fermentation, the concentration of free terpenes and aromatic alcohols differed slightly among yeasts, but differences were below the sensory thresholds reported for each compound. Post-fermentation thermal processing reduced the glycoconjugates by an average of 33% for all treatments, with the greatest reduction occurring with the VL1 strain. Storing wines for 45 days sur lie lessened the glycoside content uniformly among treatments by 52%.
Five volatile thiols previously identified in Sauvignon blanc wines, 4-mercapto-4-methylpentan-2-one (4MMP), 4-mercapto-4-methylpentan-2-ol (4MMPOH), 3-mercapto-3-methylbutan-1-ol (3MMB), 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (A3MH) were found to be present in wines made from several other white Vitis vinifera grape varieties. An assay of these volatile thiols showed that concentrations of 4MMP, 3MH, and A3MH were considerably higher than the perception thresholds in certain wines made from Gewurztraminer, Riesling, Colombard, Petit Manseng, and botrytized Semillon. The impact of volatile thiols on the aromas of wines made from these grape varieties was investigated for the first time.
Grape glycosides are, in part, important aroma and flavor precursors. Their quantification may offer a means of determining the impact of viticultural practices, such as leaf removal, on potential wine quality. Fruit zone leaf removal of Riesling and Chardonnay grapevines grown at two sites for two seasons was evaluated for its influence on total and phenol-free grape glycosides at harvest. Vines were trained to a low bilateral cordon system at one vineyard and a high bilateral cordon at the other. The concentrations of total and phenol-free glycosides were higher in Riesling and Chardonnay fruit from leaf-pulled vs control vines at three of four harvest dates. Phenol-free glycosides averaged 80% of the total in Riesling juice and 66% of the total in Chardonnay. Grapevine canopy microclimate plays an important role in determining fruit composition, although knowledge about the relationship between microclimate and aroma/flavor development is limited. This study illustrates the affect of microclimate manipulation on grape glycosides, important components of fruit quality.
Selective leaf removal from fruit zones of mature Riesling grapevines grown at two northern Virginia (≃39°N) sites was evaluated over two seasons for its influence on total grape glycosides. Two to four leaves per shoot were removed three weeks after bloom from around fruit clusters grown on a high (1.8 m above ground) bilateral cordon at one vineyard, and a low (1.2 m) bilateral cordon at the other. Leaf removal increased the percentage of sunlight penetration into the canopy fruit zone in three of four measurements. The concentration of total glycosides, estimated by the analysis of glycosyl-glucose, was mostly higher in the fruit from leaf-removed vines than control vines for both the low-trained and high-trained vineyards. The sum of the concentration of selected bound monoterpene alcohols (geraniol, nerol, and linalool), and bound aromatic alcohols (benzyl alcohol and 2-phenylethanol), was also higher in fruit of leaf-removed canopies than controls at most sampling dates.
To characterize the changes in aroma resulting from the Methode Champenoise process, 28 base wines and their corresponding sparkling wines were profiled by descriptive analysis. The base wines were made from Chardonnay, Pinot blanc, Pinot Meunier, and Pinot noir grapes grown in Anderson Valley, Carneros District, Napa Valley, and Russian River Valley. Intensities of seven aroma attributes were rated in base wines and sparkling wines separately. Principal Component Analyses (PCA) of the base wine data separated the white from red varietal wines, whereas the PCA of the sparkling wines did not cluster wines by region or variety. When differences in intensity ratings between each sparkling wine and its corresponding base wine were analyzed by PCA, the first dimension separated the white from red varietal wines. This pattern resulted primarily from the larger increase in citrus and apple intensity in red varietals and in vanilla/butter aroma in whites during the 18 months on yeast following the secondary fermentation.
Interest in the plant cell nucleus has heightened in recent times due to the rapid advances being made in the biochemistry of its DNA, RNA, and protein components. While the cytological observations on chromosome structure and behavior have held interest in the nucleus for some time, application of recombinant DNA technology, sequencing and hybridization techniques to chromosomal DNA have focussed attention on the nucleus even more. Studies on gene expression have also seen many advances recently and much has been learnt about the events of eukaryotic mRNA biogenesis (Nevins 1983). Recognition of promoters and sites of transcriptional initiation, poly(A) addition, RNA splicing, methylation and the process of nuclear-cytoplasmic transport have been investigated and all need nuclear preparations at some stage for further investigation in the eukaryotic organism. Possession of a well-defined nucleus is one of the criteria separating eukaryotes from prokaryotes, and it is the pathway of mRNA synthesis involving this RNA processing and transport out of the nucleus which sets the eukaryotes apart from the prokaryotes as much as the other cytologically recognized nuclear differences. There is then great interest in nuclear preparation for these and other biochemical studies. This chapter will deal in the main with the larger-scale preparation of nuclei from plant cells for these biochemical studies. The properties of the nucleus will be dealt with only in so far as it explains the various techniques exploiting those properties which are used in nuclear preparation. Particular attention will be given to different procedures adopted for nuclear preparations for different purposes. The development of efficient protoplast preparation methods from plant cells has had a great effect on organelle investigations in plants (see Wagner, this vol.) including nuclear studies.
The effect of elevated temperatures during storage on wine aroma was determined for commercial Chardonnay wines with and without oak aging. A significant difference in aroma was detected between the control wine (held at 5degreesC) and the unoaked (94-U) and oaked (94-O) 1994 wines, after they were held at 40degreesC for five and seven days, respectively. The 1993 oak-aged wine (93-O) was more resistant to the storage treatment, with a significant difference produced only after nine days at 40degreesC. After five to nine days of heated storage, only very small decreases in glycosyl glucose (GG) level were observed, suggesting that the initial changes affecting aroma were not a result of hydrolysis of glycosides. To characterize the changes in aroma produced by heating, wines stored at 40degreesC for 0, 15, 30, and 45 days were profiled by descriptive analysis using trained judges. Upon heating of all wines (93-O, 94-O, 94-U), the intensity of floral and fruity notes decreased, while aromas associated with oak and aging increased: honey, butter/vanilla, oak, tea/tobacco and rubber. The first 15 days of heating resulted in significant increases in the honey, rubber and tea/tobacco attributes and decreases in citrus, tropical fruit, green apple and floral aromas. Increasing the storage time to 30 days resulted in a further decrease in fruity aromas and increase in honey, rubber, tea/tobacco, butter/vanilla, and oak. Few further changes in aroma occurred when storage was extended to 45 days. Although larger decreases in GG concentration occurred upon heating for 15 to 45 days, no consistent relation between GG and the attributes was found.
A technique has been developed for the rapid assay of monoterpene flavorants of grape juices. Steam distillation of juice at neutrality yielded free aroma compounds of the grape while, at low pH, monoterpenes derived from the polyols and glycosidically bound forms were collected. Reaction of these distillates with a vanillinsulfuric acid reagent gave a color, the intensity of which was proportional to the concentration of monoterpenes in the two fractions. Thus analytical figures for free volatile terpenes (FVT) and potential volatile terpenes (PVT) of the grape were obtained. The presence of sulfur dioxide in juice interfered with the determination, necessitating treatment with H2O2 before color development. Other non-monoterpenoid juice constituents did not interfere, except trans-hex-2-en-1-ol, which would have contributed to FVT figures. Experiments with different categories of reference monoterpenes, including polyols and glycoside derivatives, demonstrated that the technique gave quantitative recovery of FVT while yields of PVT were 55 to 80 percent. Solutions containing mixtures of different monoterpene categories on assay gave satisfactory recoveries of FVT and PVT. In a preliminary survey, the assay was applied to samples of mature grapes of several varieties and figures for FVT and PVT correlated with the recognized aroma characteristics of the cultivars examined. The value of the assay was demonstrated in observing the increase in concentration of monoterpene flavor compounds in developing Muscat of Alexandria grapes.
Volatile components liberated by hydrolysis of C-18 reversed phase isolates from Vitis vinifera cv. Shiraz juice were evaluated by sensory descriptive analysis. The isolates were hydrolyzed at pH 3.2 or by treatment with a non-selective glycosidase enzyme. Shiraz juices assigned as high and low 'quality', each sourced from two regions and sampled in 1988 and 1989, were studied. Wines made from the 1989 juices were also subjected to descriptive analysis. The results showed that for one pair of wines and all but one pair of hydrolysates, the quality differences could be distinguished and quantified. The glycosidic hydrolysates prepared by both methods were found to contribute non-berry attributes to wine such as 'stalky', 'earthy', and 'cigar/tobacco'. Wines considered to be of high quality were rated higher in these non-berry attributes than their low quality counterparts, and it may be deduced that glycosidic hydrolysates contain aroma compounds that are important to high quality Shiraz wine.
Grape-derived aroma and flavor precursors exist partially as nonvolatile, sugar-bound glycosides. Hydrolysis of these compounds may modify sensory attributes and potentially enhance wine quality. Prefermentation skin contact at two temperatures and alcohol content at press were monitored to determine effects on Cabernet Sauvignon glycosides. Total, red-free, and phenol-free glycoside concentrations were estimated by the quantification of glycosyl-glucose. After three days, cold soak (10degreesC) increased total glycosides by 103%, red-free glycosides by 81%, and phenol-free glycosides by 88%. During the same period, ambient soak (20degreesC) increased total glycosides by 177%, red-free glycosides by 144%, and phenol-free glycosides by 106%. A reduction in the ratio of red-free glycosides to the total and the ratio of phenol-free glycosides to the total occurred during fermentation. At fermentation completion, red-free glycosides comprised 30% of the total, and phenol-free glycosides were 23% of the total glycosides. Wines produced by early pressing (10% sugar) had 25% more total and red-free glycosides than those pressed at dryness.
Grape glycosides are, in part, an important source of varietal wine aroma and flavor. Aglycones may be aliphatic residues, monoterpenes, sesquiterpenes, norisoprenoids, or phenolic compounds. Studies were undertaken to evaluate and compare methods of isolating non-phenolic or phenol-free glycosides. Phenol-free glycoside fractions were obtained by three isolation methods: the addition of polyvinylpolypyrrolidone (PVPP), isolation at pH 10.0 using C18 solid phase extraction cartridges, or isolation at pH 13.0 using OasisTM hydrophilic-lipophilic balance (HLB) extraction cartridges. Glycoside separation using the Oasis cartridges reduced the phenol content of the phenol-free glycoside fractions in Chardonnay juice and wines by an average of 49.7% compared to 33.6 % using C18. The differences in the phenol concentration in the phenol-free glycoside fractions with these two methods were greater with red juices and wines. For the Cabernet Sauvignon juice and wines the phenol concentration was reduced by an average 103% and 73% using the Oasis and C18 cartridges, respectively.
The effect of elevated temperatures during storage on wine aroma was determined for commercial Chardonnay wines with and without oak aging. A significant difference in aroma was detected between the control wine (held at 5degreesC) and the unoaked (94-U) and oaked (94-O) 1994 wines, after they were held at 40degreesC for five and seven days, respectively. The 1993 oak-aged wine (93-O) was more resistant to the storage treatment, with a significant difference produced only after nine days at 40degreesC. After five to nine days of heated storage, only very small decreases in glycosyl glucose (GG) level were observed, suggesting that the initial changes affecting aroma were not a result of hydrolysis of glycosides. To characterize the changes in aroma produced by heating, wines stored at 40degreesC for 0, 15, 30, and 45 days were profiled by descriptive analysis using trained judges. Upon heating of all wines (93-O, 94-O, 94-U), the intensity of floral and fruity notes decreased, while aromas associated with oak and aging increased: honey, butter/vanilla, oak, tea/tobacco and rubber. The first 15 days of heating resulted in significant increases in the honey, rubber and tea/tobacco attributes and decreases in citrus, tropical fruit, green apple and floral aromas. Increasing the storage time to 30 days resulted in a further decrease in fruity aromas and increase in honey, rubber, tea/tobacco, butter/vanilla, and oak. Few further changes in aroma occurred when storage was extended to 45 days. Although larger decreases in GG concentration occurred upon heating for 15 to 45 days, no consistent relation between GG and the attributes was found.
Polyphenols are an important fraction of the non-volatile components in the red wine matrix, and they are influenced in quantity and composition at all stages from the grape growing conditions until the time the wine is consumed. Evidence of their interaction with volatiles has been found, and this should affect wine flavour. A range of 12 commercial Spanish red wines from different regions and ages was analysed for their sensory properties, volatile composition in solution and headspace, and their non-volatile phenolic components. Maturation was the most important effect on sensory perception, while the chemical data showed also individual differences between the wines and their regions of production. Headspace volatiles and the phenolic fraction showed better correlations with the sensory perception, but volatiles in solution did not give a good prediction, though there were changes related to maturation. Some flavour components showed changes in their volatile behaviour in the matured wines. This supports the hypothesis that changes in the behaviour of the volatile fraction are related to the evolution of phenolic compounds.
The formation of flavor in fermented beverages is due to various biosynthetic mechanisms. In wine, flavors arise as the result of compounds: 1. Originating from the native fruit (grap) 2. Which are formed or altered during the various processes employed in production 3. Which are developed or transformed by yeast during fermentation 4. Arise during the aging process In this review the results of investigations on the development of flavors in grape and wine will be discussed. Special attention will be devoted to the effects of specific processes in winemaking on the development of flavor.
Three new flavour-active mercapto-alcohols have been identified in Sauvignon blanc wines: 4-mercapto-4-methylpentan-2-ol, 3-mercaptohexan-1-ol and 3-mercapto-3-methylbutan-1-ol. The first two have a perception threshold of the order of 60 ng/l in an aqueous alcohol solution and their respective odours are reminiscent of citrus zest and grapefruit. The perception threshold of 3-mercapto-3-methylbutan-1-ol, with its odour of cooked leeks, is higher (1500 ng/l in the same solution). These three compounds may contribute towards the typical aroma of Sauvignon blanc wines. © 1998 John Wiley & Sons, Ltd.
3-Mercapto-2-methylpropanol, an odorous compound recently identified in red wines, was extracted from a red wine variety,
using a low-temperature vacuum distillation coupled with a specific reversible thiol capture. The analysis of the diacetylated
wine extract by enantioselective multidimensional gas chromatography with mass spectrometry detection revealed the presence
of only one enantiomer, (R)-3-mercapto-2-methylpropanol. Although both of the optical isomers are characterized by the same broth and sweat odour, they
have very different odour thresholds. The amounts of (R)-3-mercapto-2-methylpropanol in young Cabernet-Sauvignon and Merlot wines can exceed its perception threshold, thus suggesting
its contribution to the aroma of these wines.
A stable isotope dilution assay was developed for the quantitative analysis of acetylpyrazine, 2-methyl-3-ethylpyrazine, 5-methyl-5H-cyclopenta(b)pyrazine, and 2-acetyl-1-pyrroline in bread crusts.Model experiments showed that these compounds, which contributed significantly to the crust flavorncan be determined with high sensitivity and accuracy. The method revealedthat the levels of the three Pyrazines lie in similar concentration ranges in the wheat and rye bread crusts. In contrast, 2-acetyl-1-pyrroline appeared at an 20-fold higher concentration in wheat crust than in rye. Comparison of two different processes for rye bread revealed that the level ofthe four compounds was twice as high in the three-stage sourdough than in zthe one-stage process.
With the increase in sensitivity and selectivity of instruments, volatiles can now be analyzed under conditions very close to those by which humans perceive aroma. However, without sensory evaluation, even precise information about the volatile composition in the nasal passages cannot predict the flavor of the system as perceived by humans. To illustrate one facet of the complexity of flavor research, multivariate statistical methods that have been used in wine flavor studies to relate sensory descriptive analysis and volatile composition are reviewed. Principal component analysis of instrumental variables is a technique to find the fewest number of volatiles that match the configuration of the sensory profile data. Generalized procrustes analysis (GPA) and Partial least squares regression (PLS) are used to model data from different data sets, such as volatiles identified by GC-MS and intensity ratings for the sensory attributes. The GPA is used to determine if the two data sets “fit each other”, whereas PLS determines underlying dimensions in each set of data that best explain the variation in the other set of data. Neither GPA nor PLS determine if any of the compounds associated with specific sensory attributes are actually responsible for specific aromas but they identify compounds on which the sensory studies should focus. These three methods are compared by the analysis of data from a study of Chardonnay wines that were profiled by descriptive analysis and the headspace volatiles identified by GC- MS, responsible for those aroma notes. However, they do identify compounds on which sensory studies should focus in subsequent research.