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Quantification of Glycosides in Grapes, Juices, and Wines through a Determination of Glycosyl Glucose
Abstract
An analytical assay for glycosylated secondary metabolites of grapes, juices and wines, through quantification of glycosyl glucose (G-G), has been optimized and validated. The glycosides are isolated on Cls reversed-phase silica gel and hydrolyzed with sulfuric acid at 100 degrees C; the released glucose is determined enzymatically. The accuracy and precision of the assay, determined from the gradients and coefficients of determination of linear regression curves for the recovery of a standard glycoside from wine, juice or homogenized fruit extract ranged, respectively, from 0.957 to 1.021 and from 0.991 to 0.997. Some examples of application of the assay are presented-the decrease of G-G in wines with aging, the range of G-G in Shiraz juices from different regions, and the development of G-G in ripening fruit.
... 7,8 Glycosylated precursors can be either monoglucoside conjugates or disaccharide glycosides, where glucose is linked with another sugar moiety such as α-L-arabinofuranosyl, α-Lrhamnopyranosyl, β-D-xylopyranosyl, or β-apiofuranosyl group, which is then bound to the aglycone. 9 Numerous aglycones have been identified from hydrolysis of wine and grape juice glycosides, including monoterpenes, norisoprenoids, aliphatics, and phenolic compounds. 9 The aroma and aroma precursor character vary significantly with grape maturity. ...
... 9 Numerous aglycones have been identified from hydrolysis of wine and grape juice glycosides, including monoterpenes, norisoprenoids, aliphatics, and phenolic compounds. 9 The aroma and aroma precursor character vary significantly with grape maturity. 10,11 In general, the increase of glycosylated precursors in grapes is a distinctive feature in the advanced stages of ripening, when sugar increase per berry has slowed and the berry is accumulating aromas and flavors. ...
Aroma potentials in early and late maturity Pinot noir grapes were investigated in two consecutive vintages. The grape samples were hydrolyzed under acidic conditions and the released odorants were studied by aroma extract dilution analysis (AEDA). Forty-nine main odor-active compounds were detected in the AEDA. The odorants released with high flavor dilution values were 1-hexanal, β-damascenone, guaiacol and vanillin, together with C6 aldehydes and alcohols, 4-vinylguaiacol, 4-vinylphenol and 1-octen-3-one. The concentrations of aroma-active compounds were further quantitated. Comparing with early harvest grapes, late harvest grapes released more β-damascenone, vanillin, 4-vinylguaiacol and 4-vinylphenol in both years according to both AEDA and quantification results, suggesting they were important aroma compounds that contribute to the characteristic of matured Pinot noir grapes.
... The majority of glycoconjugate terpenes are determined after post-hydrolysis treatment, due to the lack of commercially available standards and the complexity and diversity of aglycones (Williams et al., 1995). Determination of free terpenes usually is based on gas chromatography (GC) with flame ionisation detectors (FIDs) or mass spectrometry (MS). ...
Six prevalent sweet potato cultivars, New Orleans, Beauregard, Japanese, Hannah, Garnet and Jewel, were selected to determine the distribution of terpenes in their flesh and peel. Free‐form terpenes were not detected in both flesh and peel in all the cultivars by using a solid phase microextraction (SPME) and gas chromatography–mass spectrometer (GC–MS) method. Major terpenes in the sweet potatoes were linalool and α‐terpineol and existed in bound form in flesh and peel. They were released as free‐form and determined after acid hydrolysis treatment. However, ultrasonication‐assisted acid hydrolysis decreased the levels of terpenes with increased treatment time because the broken‐down free‐form terpenes were volatile and rapidly evaporated or oxidised. For the selected cultivars, the Garnet, Jewel and Japanese cultivars had the greatest levels of linalool, while the Beauregard and New Orleans cultivars had the greatest level of α‐terpineol. Also, the concentration of linalool or α‐terpineol in the peel of each cultivar was approximately two times greater than in its flesh. This study revealed the bound form terpenes and their distribution in sweet potatoes. The results explored the potential utilisation of sweet potato peel as a natural source of terpenes.
... Це є основною стабільного розвитку галузі виноградарства. Сучасні сорти відрізняються величиною грона та ягід, їх смаковими властивостями, високим вмістом цінних речовин та споживних цукрів [8,9]. ...
Вирощування винограду столового в регіоні має особливе господарське значення, що обумовлене господарсько-цінними харчовими і дієтичними властивостями столового винограду та продукції переробки. Мета. Метою було встановити особливості формування врожайності п’яти столових сортів винограду та визначити елементи структури врожайності та особливості формування кущів винограду столових сортів, провести аналіз впливу окремих елементів на товарну продуктивність. Методи: Використовували для дослідження сорти винограду столового Аркадія, Надєжда АЗОС, Преображеніє, Дубовський розовий, Румейка. Насадження закладено за схемою садіння 3,5 × 1,5 м. Повторність трьохкратна. Ділянки розміщено послідовно, по десять облікових кущів. Вирощувався на краплинному зрошувані в підзонi Північного Степу України. Клiмат помiрно-континентальний, характеризується чiтко означеною посушливiстю. Результати. Протягом періоду активного росту та формування продуктивної лози проводили аналіз такого показника як довжина пагону для характеристики онтогенезу рослини. Вона поступово зростає навіть після настання товарного плодоношення. Значимим для продуктивності є два чинника більш швидке лінійне наростання вегетативної маси в онтогенезі на другий-третій рік культивації та відносне використання частки цієї маси для формування товарної продукції. Було встановлено відносне значення окремих ознак та їх вплив на врожайність з одиниці площі. Такі ознаки як довжина пагонів діаметр пагону, площа поперечного перерізу та його об’єм з вивчених морфометричних ознак суттєво не вплинули на врожайність. Середня довжина пагону та визріла частина грона вже були статистично достовірні в своєму впливі. Серед ознак, що безпосередньо відносяться до структури врожайності статистично значимо вплинули всі, але більше значення мали середня маса грона та продуктивність з куща. Саме вони обумовили перевищення за врожайністю трьох сортів Надєжда АЗОС, Преображеніє, Дубовський розовий. Висновки. Суттєво підвищення продуктивності показали три з п’яти досліджених сортів, а саме Надєжда АЗОС, Преображеніє, Дубовський розовий, що перевищили інші два сорти за такими ключовими показниками як довжина пагону (частково) та визріла частина грона з морфометричних та показники кількість грон, середня маса грона та продуктивність з куща. Переваги за продуктивністю обумовлені більш високими темпами росту та розвитку у цих сортів на другий-третій рік вирощування. В майбутньому планується провести аналіз продуктивності вирощуваних сортів в умовах закритого грунта та аналіз якості отриманої товарної продукції.
... Важливим елементом є наявність в теплицях системи крапельного зрошення та антифросту (насичення приміщення туманом). Таким чином можна суттєво відрегулювати температуру та полегшити обробку від шкідників [8,9]. ...
... Glycoside analysis involves a complex methodology combining extraction and detection by gas chromatography (Alegre, Sáenz-Navajas, Hernández-Orte, & Ferreira, 2020;Asproudi, Petrozziello, Cavalletto, & Guidoni, 2016;Liu, Zhu, Ullah, & Tao, 2017;Wang et al., 2020;Wirth et al., 2001), requiring sample preparation and consuming time. Williams et al. (1995) developed the only method actually fast enough to assess these glycoconjugates (the glycosyl-glucose or G-G method), which has been further modified by several authors (Arévalo Villena, Díez Pérez, Úbeda, Navascués, & Briones, 2006;Iland, Cynkar, Francis, Williams, & Coombe, 1996;Zoecklein, Douglas, & Jasinski, 2000). The technique uses the measure of the glucose released from precursors after acidic hydrolysis, allowing the determination of the sum of glycoconjugates (both volatile and non-volatile), underestimating the contribution of differently volatile glycosides to wine aroma. ...
Grape variety, vinification, and ageing are factors conditioning the aroma of a wine, with volatile secondary metabolites responsible for the so-called grape varietal character. Particularly, grape glycosylated norisoprenoids are mostly responsible for the sensory profile of Tannat wines, making relevant the use of fast instrumental tools to evaluate their concentration, allow classifying grapes and defining the optimum maturity for harvest. NIR spectroscopy is a fast, non-destructive technique, which requires minimal sample preparation. However, its quantitative applications need chemometric models for interpretation. In this work, a NIR-ANN calibration was developed to quantify norisoprenoids in Vitis vinifera cv. Tannat grapes during maturation and harvesting. Glycosidated norisoprenoids were determined by GC-MS. The ANN adjustments showed better performance than linear models such as PLS, while the best calibration was obtained by homogenising grape samples when comparing to grape juice; making possible to fit a model with an error of 146 μg/kg.
... Microvinification (60 kg of grape) was conducted in an identical fashion for all irrigation treatments by the same winemaker. The aromatic potential of the Arvine grape variety was evaluated by the Glycosyl-Glucose (G-G) method, according to Williams et al. (1995), and the precursor 3-mercaptohexanol (P-3MH) was analyzed according to the Luisier et al. (2008) method on musts, after crushing and the addition of sulphites. ...
Aims: The aim of the present study was to analyse the impact of different water regimes on the physiological and agronomical behavior of an aromatic white grapevine (cv. Arvine) by means of various levels of irrigation. The consequences of the plant water status were evaluated by carrying out a chemical (aromatic precursors) and sensorial analysis of the resulting wines.
Methods and results: Adult vines of Vitis vinifera L. cv. Arvine grafted onto 5BB were subjected to different water regimes (various levels of irrigation) during the growing season. Physiological indicators were used to monitor the plant water status [pre-dawn leaf (ΨPD) and stem (ΨSTEM) water potentials and carbon isotope composition (d13C) in the must]. Gas exchange (net photosynthesis AN and transpiration E), stomatal conductance (gs), yield parameters, berry composition at harvest, analysis of potential grape aromatic properties (glycosyl-glucose G-G, precursor 3-mercaptohexanol P 3-MH) and the sensorial quality of wines were analysed over a period of 8 consecutive years (2009-2016) in the Agroscope experimental vineyard in Leytron under the relatively dry conditions of the Rhône valley in Wallis, Switzerland.
In the non-irrigated vines, the progressively increasing water deficit observed over the season reduced the leaf gas exchange (AN and E) and gs. The intrinsic water use efficiency (WUEi, A/gs) increased over the season and was greater in the vines that had suffered water restriction than in the irrigated vines. The rise in WUEi was correlated with an increase in d13C in the must sugars at harvest. A decrease in plant vigor was observed in the water stressed vines over multiple years. Moderate to high water stress during fruit ripening lowered the contents of total and malic acidity in the musts and the content of yeast available nitrogen (YAN). On the other hand, contents in sugar and the aromatic precursor (P-3MH) in berries were not influenced by the vine water status. The G-G values for berries increased with rising water stress in the non-irrigated vines. The wines from the plants subjected to water stress and to yeast available nitrogen deficiency (non-irrigated vines during hot and dry seasons) had a less distinctive typicity, and developed a lower aromatic expression with a more bitter taste, than the wines from the non-stressed plants. Overall, and compared with the stressed vines, the organoleptic characteristics and quality of Arvine wines from vines which had not undergone restrictions in water and nitrogen during the growing season were appreciated more.
Conclusions: The vine’s physiological behavior (leaf gas exchange, plant vigor) and agronomic parameters (yield, berry composition), together with the quality of white aromatic Arvine wines, were strongly influenced by vine water regimes during the growing season.
Significance and impact of the study: Vine water status and must nitrogen contents are key factors in grape composition and in the sensorial quality of resulting aromatic white wines.
... D'autres méthodes portent sur la détermination enzymatique des sucres libérés dans l'hydrolyse, indicateurs de la teneur en précurseurs dans l'échantillon (Williams et al. 1995). ...
La présence d’un métabolisme actif des bactéries lactiques dans le vin logé en fûts de chêne induit une augmentation de la concentration des composés volatils du bois. Ce phénomène a récemment été attribué à l'activité glycosidique des bactéries. Le glucoside précurseur d'un composé majeur de l’arôme boisé (whiskylactone) a déjà été identifié et quantifié dans le bois de chêne. Mais aucune donnée n'était disponible jusqu’à présent concernant l’identification formelle des précurseurs pour d’autres arômes du bois de chêne.Un premier travail a permis de montrer que les précurseurs monoglycosides n'existaient pas dans le bois de chêne, dans les spiritueux et dans le vin. L'étude a été réalisée à l’aide de la technique UPLC-FT/MS, en utilisant la vanilline-β-D-glucopyranoside, la vanilline-β-D-xylopyranoside, et la coniféraldéhyde-β-D-glucopyranoside, synthétisées par réaction par transfert de phase. Dans un deuxième temps, une purification des précurseurs glycosidiques complexes a été réalisée à l’aide de la Chromatographie de Partage Centrifuge (CPC) à partir d’un extrait de bois de chêne. Le choix du système de solvants a été basé sur une égale répartition dans les deux phases de la libération d’arômes par hydrolyse enzymatique. Cela a conduit à la détermination du nouveau concept de coefficient de partage d’activité Kca. Après purification et fractionnement, la vanilline galloylglucoside, le triméthoxyphénol-galloyl-glucoside et le macarangioside E ont été isolés du bois et identifiés par HPLC-ESI-MS et RMN. Ces précurseurs ont été quantifiés dans différentes espèces de chêne par HPLC-QqQ-MS. Ces trois composés sont les précurseurs respectivement de la vanilline, du 3,4,5-triméthoxyphénol et du 3-oxo-α-ionol. Par dégradation thermique, le macarangioside E peut conduire à la mégastigmatriénone et à la 4-oxo-isophorone, dont les notes aromatiques sont le tabac et l’encens. Ces composés complètent la connaissance que nous avons de l’arôme boisé du vin et contribuent ainsi à une meilleure compréhension de la genèse du bouquet tertiaire.
... Further studies showed that Muscat grapes consist of approximately 90% glycosidically bound monoterpenoids and only 10% free volatile monoterpenoids (Park et al. 1991). The chemical structures of the precursors have been intensively studied (Günata et al. 1985a, b;Williams et al. 1995). The aglycones are mainly bound to disaccharides that connect β-D-glucopyranose with a second sugar molecule, such as α-Larabinofuranose, α-L-rhamnopyranose, or β-D-apiofuranose (Winterhalter and Skouroumounis 1997). ...
Although there are many chemical compounds present in wines, only a few of these compounds contribute to the sensory perception of wine flavor. This review focuses on the knowledge regarding varietal aroma compounds, which are among the compounds that are the greatest contributors to the overall aroma. These aroma compounds are found in grapes in the form of nonodorant precursors that, due to the metabolic activity of yeasts during fermentation, are transformed to aromas that are of great relevance in the sensory perception of wines. Due to the multiple interactions of varietal aromas with other types of aromas and other nonodorant components of the complex wine matrix, knowledge regarding the varietal aroma composition alone cannot adequately explain the contribution of these compounds to the overall wine flavor. These interactions and the associated effects on aroma volatility are currently being investigated. This review also provides an overview of recent developments in analytical techniques for varietal aroma identification, including methods used to identify the precursor compounds of varietal aromas, which are the greatest contributors to the overall aroma after the aforementioned yeast-mediated odor release.
... Not only monomeric polyphenols are released under acidic conditions but also the sugar moieties from glycosides may be cleaved. The original glycosyl-glucose assay by Williams et al. (1995;40) was primarily developed for the determination of glycosidic bound aroma precursors but may also be applied for the determination of anthocyanins or other flavonoid glucosides. ...
... Some native Saccharomyces and non-Saccharomyces strains were identified that show glycosidase activity in an esculin solid medium [67]. This technique directly correlates with the glycosyl-glucose (GG) index determination method that measures their enzymatic hydrolysis of glycosylated compounds in grape must [68]. The glycosidic activity related to S. cerevisiae has been proven in Riesling and Chardonnay musts [69,70] and is weakly sensitive to the presence of sugar, but its action is very reduced due to must and wine pH [57,71,72]. ...
Yeast had participated with humans in food fermentation since the production of wine and bread, more than 10,000 years of shared history. It is well understood that fungi diversity is still underestimated and that we are far from understanding its importance and potential impact in biotechnology. Flavor compounds as “secondary metabolism” are very sensitive to fermentation conditions and mixed cultures, and although we had experience an exponential development of molecular biology in the last 30 years, metabolomics is still in its infancy. It was demonstrated in recent years that increase strain and species yeast diversity in a fermentation system increases sensory complexity and chemical aroma compound diversity in the final fermented product. Flavor compounds had many key functions for yeast, such as for survival and dispersion strategies, pheromone and defense mechanisms, and “quorum sensing” mechanisms for cell communication. Humans had taken advantage of many of these functions to increase taste and food sensory pleasure for a more exigent consumer, a phenomenon called “yeast domestication.” We focus this chapter mainly in the recent discussed yeast synthetic pathways for the formation of phenylpropanoid and terpenoid aroma compounds. In addition, we will emphasize the current knowledge that grape and wine microbiology research has contributed to understand how complex natural and inoculated yeast flora can affect flavor quality. The flavor phenotype concept and how to screen natural flora and develop consortia starters to innovate in food biotechnology are discussed.
... While glycosylated compounds are not contributing to aroma directly, they are considered as important aroma precursors (Maicas and Mateo, 2005). Glycosylated compounds can be hydrolyzed by acid (Winterhalter and Schreier, 1994;Williams et al., 1995;Maicas and Mateo, 2005) or by enzymes (Günata et al., 1985;Black et al., 2015) during fermentation. Upon hydrolysis, the aglycon is liberated in the wine, and becomes sensorially active. ...
La distillation dite « charentaise » est une méthode de distillation discontinue permettant la production d’eaux-de-vie de cognac à partir de vin. La distillation est effectuée dans des alambics en cuivre avec un chauffage à feu nu qui peut être favorable à la génération de composés volatils. Or, les précurseurs et les mécanismes de réactions formant ces composés, pendant la distillation, restent mal connus. La première partie de l’étude consiste à identifier les composés volatils formés au cours de la distillation charentaise. Le bilan matière effectué sur de nombreux composés lors du procédé de distillation a révélé que 2 esters, 3 aldéhydes, 3 terpènes et 12 norisoprénoïdes étaient générés. Par la suite, deux distillations utilisant un mode de chauffe différent (feu nu et vapeur) ont été menées sur un alambic pilote. Le but était d’évaluer l’impact du mode de chauffe sur la génération en composés volatils. L’étude a montré que le mode de chauffe a peu d’effet sur la génération en composés volatils. De plus, les composés formés sont similaires à ceux formés lors de la distillation en alambic traditionnel. Enfin, le troisième axe de l’étude porte sur la caractérisation de l’hydrolyse acide de l’α- terpenyl-O-β-glucopyranoside, précurseur impliqué dans la formation de l’α-terpineol, identifié comme étant généré lors de la distillation charentaise ainsi qu’en alambic pilote. Le suivi de la dégradation dans un réacteur hermétiquement fermé de l’α-terpenyl-O-β-glucopyranoside et dans des conditions représentatives du vin durant la distillation montre l’hydrolyse pour former l’α- terpineol, le trans-terpin et son isomère. Cette étude a révélé que l’hydrolyse du précurseur est favorisée en milieu aqueux et suit une cinétique d’ordre 1
... The organoleptic characteristics of beverages (taste and aroma) can be enhanced by glycosidases that hydrolyse odourless and non-volatile glycosidic precursors of the fruits [111]. Glycosidase activities comprise β-D-glucosidase, β-D-xylosidase, β-D-apiosidase, α-L-rhamnosidase, and α-L-arabinofuranosidase. ...
Candida stellata is an imperfect yeast of the genus Candida that belongs to the order Saccharomycetales, while phylum Ascomycota. C. stellata was isolated originally from a must overripe in Germany but is widespread in natural and artificial habitats. C. stellata is a yeast with a taxonomic history characterized by numerous changes; it is either a heterogeneous species or easily confused with other yeast species that colonize the same substrates. The strain DBVPG 3827, frequently used to investigate the oenological properties of C. stellata, was recently renamed as Starmerella bombicola, which can be easily confused with C. zemplinina or related species like C. lactis-condensi. Strains of C. stellata have been used in the processing of foods and feeds for thousands of years. This species, which is commonly isolated from grape must, has been found to be competitive and persistent in fermentation in both white and red wine in various wine regions of the world and tolerates a concentration of at least 9% (v/v) ethanol. Although these yeasts can produce spoilage, several studies have been conducted to characterize C. stellata for their ability to produce desirable metabolites for wine flavor, such as acetate esters, or for the presence of enzymatic activities that enhance wine aroma, such as β-glucosidase. This microorganism could also possess many interesting technological properties that could be applied in food processing. Exo and endoglucosidases and polygalactosidase of C. stellata are important in the degradation of β-glucans produced by Botrytis cinerea. In traditional balsamic vinegar production, C. stellata shapes the aromatic profile of traditional vinegar, producing ethanol from fructose and high concentrations of glycerol, succinic acid, ethyl acetate, and acetoin. Chemical characterization of exocellular polysaccharides produced by non-Saccharomyces yeasts revealed them to essentially be mannoproteins with high mannose contents, ranging from 73-74% for Starmerella bombicola. Numerous studies have clearly proven that these macromolecules make multiple positive contributions to wine quality. Recent studies on C. stellata strains in wines made by co-fermentation with Saccharomyces cerevisiae have found that the aroma attributes of the individual strains were apparent when the inoculation protocol permitted the growth and activity of both yeasts. The exploitation of the diversity of biochemical and sensory properties of non-Saccharomyces yeast could be of interest for obtaining new products.
... The glycosides eluted from columns were filtered and stored at −20 °C until required. Glycoside concentration extracted was estimated by the analysis of glycosyl-glucose (Williams et al. 1995) after acid hydrolysis. ...
Autochthonous Oenococcus oeni strains (MS9, MS20 and MS46) with good malolactic performance and yielding adequate diacetyl levels, were selected to investigate the effect of synthetic and grape glycosides on bacterial growth, substrate utilization and β-glucosidase (βGlu), α-arabinofuranosidase (αAra) and α-rhamnopyranosidase (αRha) activities in a wine-like medium containing 6% ethanol, pH 4.0 (WBM). Then, changes in the volatile compounds profile were evaluated at the end of malolactic fermentation (MLF) carried out by the MS46 strain in WBM containing 1 mg L⁻¹ of natural glycoside. All strains grew and efficiently degraded l-malic acid in WBM where βGlu and αAra activities were found but not αRha. In presence of a synthetic glycoside (eriodictyol 7-O-β-rutinoside) βGlu activity was significantly enhanced for two of the cultures tested (MS20 and MS460) while a low αRha activity was induced, presenting MS46 the better performance. Glycosides extracted from fermented grape musts under different conditions allowed maximum growths, l-malic acid utilization rates and glycosidase activities in the MS46 strain. Thus, βGlu, αAra and αRha activities increased between 30–50 and 3–11% respectively. This indirectly correlated to significant changes in total esters and higher alcohols at the end of MLF, which increased by up to 140 and 30% respectively. Moreover, ethyl and acetate esters formed up to 100-fold than alcohols or esters degraded highlighted the main role of this microorganism in the esters synthesis. Results obtained encourage the potential use of selected indigenous O. oeni strains as a tool to enhance wine complexity through MLF, mainly on highly fruity aroma.
... Previous research suggests that this spent hop material contains residual compounds that play an important role in the flavor and aroma of beer (8); consequently, several patents have been issued for the preparation and use of additional extracts prepared from the spent hop material (7,15). Many plant systems, for instance grapes, contain nonvolatile, water-soluble glycosides (21,29) that vary owing to cultivar (13,30) and may contribute to aroma after undergoing hydrolysis. Published research demonstrates that these compounds exist in hops and spent hop material (8,15,24). ...
The essential oil fraction of hops clearly plays a significant and important role in their contribution to the aroma of beer, yet the potential role of water-soluble flavor precursors in hops is much less certain. The study presented herein investigated a range of glycoside hydrolysis techniques on the aqueous extracts of " spent " hops obtained after supercritical CO 2 extraction of hop pellets. A range of enzyme treatments, acid hydrol-ysis, and yeast fermentations were compared with each other and against an untreated control by measuring the volatile aroma composition of the spent hop treatments using stir-bar sorptive extraction and gas chromatog-raphy–mass spectrometry. In general, the enzyme systems show promise for investigating the broad range of glycosides in hops and offer a similar scale of aglycone delivery as yeast fermentations, whereas acid hydroly-sis may offer a relatively quick gauge of total content of glycosidically bound terpene alcohols. Eighteen different hop varieties were examined for glycoside composition using one of the enzyme techniques. Selection was based on their genetic similarity or dissimilarity (pedigree), importance to the brewing community, and input from brewers, hop researchers , and hop breeders. Clear differences were apparent in the terpene alcohols following glycoside hydrolysis across these hop varieties, most notably with Columbus and Centennial hops. However, because of the high usage levels used in this study (50 g of spent hops/L of buffer), brewers are cautioned against overstating the importance of the glycoside fraction to the overall aroma of hops in beer.
... The analyses of total glycosides (TGGs) and phenol-free glycosides (PFGGs) were performed as described by Williams et al. (1995) and modified by Zoecklein et al. (2000). ...
Vineyard applications of foliar nitrogen (N) and sulfur were evaluated in the Yadkin Valley of North Carolina in 2011 and 2012 as a means to modify grape composition of Vitis vinifera cv. petit manseng. Four treatments were applied each year in a randomized complete block design with six replicates of six vines each: untreated control, soil N at 30 kg/ha, foliar N at 15 kg/ha and foliar N at 15 kg/ha plus sulfur at 5 kg/ha. Fruit ammonia and yeast assimilable nitrogen (YAN) concentrations increased in foliar-treated vines both seasons compared to control vines. Total glycosides (TGGs) increased ∼80% in foliar N/sulfur-treated vines compared to control vines in 2011, and TGGs increased ∼157% in foliar N/sulfur-treated vines relative to glycoside level in foliar N alone in 2012. Foliar N and foliar N/sulfur applications increased the majority of amino acid concentrations analyzed in 2011. Measured concentrations of various amino acids, partly responsible for aroma and flavor of petit manseng wines, were differentially dependent on the method of N application. Foliar applied nitrogen may be an effective technique to contribute to berry composition optimization of petit manseng grown in a warm, humid climate.
... Many interactions between hops and yeast have been investigated (10); however, the contribution of hop-derived glycosides to aroma in finished beer upon yeast hydrolysis remains unclear. In contrast, significant research on the topic in other fermented beverages, such as wine (11)(12)(13)(14)(15), shows clear contributions from hydrolysed glycosides to aroma. Besides work by Daenen et al. (16) and Kanauchi and Bamforth (17), little work has been done on investigating the β-glucosidase activity of different brewing-related yeast strains in relation to hop-derived aroma in beer. ...
Previous studies show that the complexity of hop aroma in beer can be partly attributed to the hydrolysis of glycosidically bound monoterpene alcohols extracted from hops during the brewing process to release volatile aglycones. However, fundamental studies that examine the extraction of glycosides during brewing and their subsequent hydrolysis by yeast have not been performed. Furthermore, extraction of other hop-derived compounds into beer shows a strong dependency on the hop cultivar being used and the point at which it is added. This study focused on the extent of glycoside extraction owing to hopping regime and cultivar, and their hydrolysis by yeast β-glucosidase activity. Glycoside concentrations of wort made with three different hopping regimes and three cultivars were measured by the difference in volatile aglycone concentrations between samples treated with purified β-glucosidase and untreated samples. Aglycone concentrations were measured by solid-phase microextraction gas chromatography–mass spectrometry. Additionally, β-glucosidase activities for 80 different yeast strains and their effect on aglycone concentration in wort were determined. Results showed that yeast have a wide range of abilities to hydrolyse glycosides with a maximum hydrolysis occurring after 3 days of fermentation regardless of yeast activity. Although it was shown that yeast are capable of glycoside hydrolysis, glycoside concentrations in wort are low and make small contributions to hop aroma. These results help explain the extent to which different brewing yeasts and hopping regimes contribute to hoppy beer aroma through the hydrolysis of non-volatile hop-derived compounds. Copyright © 2017 The Institute of Brewing & Distilling
... Some native Saccharomyces and non-Saccharomyces strains were identified that show glycosidase activity in an esculin solid medium [67]. This technique directly correlates with the glycosyl-glucose (GG) index determination method that measures their enzymatic hydrolysis of glycosylated compounds in grape must [68]. The glycosidic activity related to S. cerevisiae has been proven in Riesling and Chardonnay musts [69,70] and is weakly sensitive to the presence of sugar, but its action is very reduced due to must and wine pH [57,71,72]. ...
Yeast had participated with humans in food fermentation since the production of wine and bread, more than 10,000 years of shared history. It is well understood that fungi diversity is still underestimated and that we are far from understanding its importance and potential impact in biotechnology. Flavor compounds as “secondary metabolism” are very sensitive to fermentation conditions and mixed cultures, and although we had experience an exponential development of molecular biology in the last 30 years, metabolomics is still in its infancy. It was demonstrated in recent years that increase strain and species yeast diversity in a fermentation system increases sensory complexity and chemical aroma compound diversity in the final fermented product. Flavor compounds had many key functions for yeast, such as for survival and dispersion strategies, pheromone and defense mechanisms, and “quorum sensing” mechanisms for cell communication. Humans had taken advantage of many of these functions to increase taste and food sensory pleasure for a more exigent consumer, a phenomenon called “yeast domestication.” We focus this chapter mainly in the recent discussed yeast synthetic pathways for the formation of phenylpropanoid and terpenoid aroma compounds.
In addition, we will emphasize the current knowledge that grape and wine microbiology research has contributed to understand how complex natural and inoculated yeast flora can affect flavor quality. The flavor phenotype concept and how to screen natural flora and develop consortia starters to innovate in food biotechnology are discussed.
... In addition, Hayasaka et al. investigated the presence of the b-Dglucopyranoside of guaiacol in juice of grapes using the acidified Amberlite IR-50 (H) ion exchange resin (Hayasaka et al. 2010). Williams et al. (1995) optimized and validated an analytical assay for glycosylated secondary metabolites of grapes, juices and wines, through quantification of glycosyl glucose. The glycosides are isolated on Cls reversed-phase silica gel and hydrolyzed with sulfuric acid at 100°C. ...
Wine aroma is defined as the cumulative effect of smell, taste and mouth-feel. Free and glycosidically bound aroma compounds (GBAC) were found in wine. The glycosidic aroma precursors are non-odorous. Most advances have been made in free aroma compounds from wine in recent decades. However, the glycosidically bound aroma compounds have received much less consideration than free aroma compounds. Acids and enzymes are responsible for transferring these glycosidic aroma precursors to aromatic compounds. This review provides an overview of recent developments in isolation, hydrolysis and characterization for glycosidic aroma precursors in wines, as well as their biological applications. It looks like that the GBAC had important biological applications, such as, genetic engineering, immobilization, aroma enhancement and biosynthesis. It will help to better understand the GBAC and free aroma compounds of wines.
... Some native Saccharomyces and non-Saccharomyces strains were identified that show glycosidase activity in an esculin solid medium [67]. This technique directly correlates with the glycosyl-glucose (GG) index determination method that measures their enzymatic hydrolysis of glycosylated compounds in grape must [68]. The glycosidic activity related to S. cerevisiae has been proven in Riesling and Chardonnay musts [69,70] and is weakly sensitive to the presence of sugar, but its action is very reduced due to must and wine pH [57,71,72]. ...
Beyond their traditional use in food fermentative processes, yeasts are currently workhorses for the production of a diverse range of products, from proteins of pharmaceutical and industrial interest to small molecules such as ethanol and glycerol. For the purposes of this article, we will focus on yeasts that are relevant for food production. Fermented food production was carried out without an understanding of the microbiological nature of the process over thousands of years until the nineteenth century. Current yeast species used in fermented food productions are mainly Saccharomycetes of the Ascomycetes phylum. Among them, Saccharomyces cerevisiae has been widely used by humanity for 1000 years due to its ability to produce alcohol and flavors from rich sugar raw materials. Molecular methods have allowed our understanding of yeast metabolism under aerobic and fermentative conditions, as well as mixed strain dynamics during wine, beer, cider, and bread production to be improved. However, yeast diversity is still currently under investigation, and nonconventional species are being studied for their known contribution to flavor and aroma, increasing the sensory complexity of foods.
... Some native Saccharomyces and non-Saccharomyces strains were identified that show glycosidase activity in an esculin solid medium [67]. This technique directly correlates with the glycosyl-glucose (GG) index determination method that measures their enzymatic hydrolysis of glycosylated compounds in grape must [68]. The glycosidic activity related to S. cerevisiae has been proven in Riesling and Chardonnay musts [69,70] and is weakly sensitive to the presence of sugar, but its action is very reduced due to must and wine pH [57,71,72]. ...
Yeast had participated with humans in food fermentation since the production of wine and bread, more than 10,000 years of shared history. It is well understood that fungi diversity is still underestimated and that we are far from understanding its importance and potential impact in biotechnology. Flavor compounds as “secondary metabolism” are very sensitive to fermentation conditions and mixed cultures, and although we had experience an exponential development of molecular biology in the last 30 years, metabolomics is still in its infancy. It was demonstrated in recent years that increase strain and species yeast diversity in a fermentation system increases sensory complexity and chemical aroma compound diversity in the final fermented product. Flavor compounds had many key functions for yeast, such as for survival and dispersion strategies, pheromone and defense mechanisms, and “quorum sensing” mechanisms for cell communication. Humans had taken advantage of many of these functions to increase taste and food sensory pleasure for a more exigent consumer, a phenomenon called “yeast domestication.” We focus this chapter mainly in the recent discussed yeast synthetic pathways for the formation of phenylpropanoid and terpenoid aroma compounds.
In addition, we will emphasize the current knowledge that grape and wine microbiology research has contributed to understand how complex natural and inoculated yeast flora can affect flavor quality. The flavor phenotype concept and how to screen natural flora and develop consortia starters to innovate in food biotechnology are discussed.
... Una limitata disponibilità idrica incrementava il contenuto degli aromi glico-coniugati nei vini prodotti a partire da uve della cv Agiorgitiko innestata su 41B, in particolare nelle condizioni di minor disponibilità idrica si determinarono le maggiori concentrazioni di terpenil-glicosilati (Koundouras et al., 2006). Un comportamento simile è stato osservato su un altro vitigno, il Moscato di Alessandria su 1103 Paulsen (Pedreira dosSantos et al., 2007), caso in cui, in condizioni di moderata disponibilità idrica a seguito dell'applicazione di condizioni di PRD e di non-irrigazione, si rilevò un incremento della concentrazione del glicosil-glucosio (GG) che, nelle uve a bacca bianca, è essenzialmente ascrivibile alla presenza di metaboliti secondari glicosilati aromatici (Williams et al., 1995Grimplet et al., 2007). In tabella 1 (a: polifenoli; b: composti aromatici) sono elencati in forma riassuntiva i risultati ottenuti per i metaboliti descritti., 1988Ojeda et al., 2002Kennedy et al., 2002Roby et al., 2004Koundouras et al., 2006AumentoOliveira et al., 2003Peyrot desGachon et al., 2005Koundouras et al., 2006Bindon et al., 2007Pedreira dosSantos et al., 2007IlWalker, 1978;Shani et al., 1993F3H, DFR, LDOX, F3'5'H, UFGT, GST, OMT) (Castellarin et al., 2007aCastellarin et al., , 2007b), con le importanti ricadute sulla qualità dell'uva di cui si è detto. ...
In this review, we address the main aspects of grapevine (Vitis vinifera L) resistance to water stress. We point to examine physiological and molecular answers, involving both primary and secondary metabolisms.
The grapevine has been generally classified as drought-avoiding or as "pessimistic" following the ecological classification of plants into "pessimists" and "optimists", even if different grapevine cultivars show different behaviours of defence against drought. This ecological classification is analogous to the physiological classification into isohydric and anisohydric plants and fundamentally linked to stomatal behaviour.
Stomatal regulation of grapevine is under hormone (ABA) and hydraulic control, the latter linked to embolism formation and recovery in xylem tissues up-stream the stomata. We review ABA effects on stomata, and their interrelationship with hydraulics of the plant. To this aim, we show that in grapevine, xylem embolism occurs and repairs during diurnal cycles, extreme water potential causing embolism, whereas an almost full recovery of water potential is needed to promote repair mechanisms. In this phase, an ABA-induced transpiration control is proposed. Aquaporins play fundamental role on water stress control, and both early or late contribution (especially in root) are discussed.
When drought-avoidance mechanisms are limiting in further plant dehydration avoidance (earlier in anisohydric varieties, but in all grape cultivars during late and/or severe drought stages) metabolic mechanisms of dehydration tolerance arise. In all tissues solutes accumulate to prevent water loss, by minimizing interferences with cellular function. Grapevines accumulate one or more types of compatible solutes (osmotic adjustment). Metabolite profiling reveals that there are higher concentrations of glucose, malate, proline, phenolics and flavour precursors upon water stress. The metabolite differences are linked to differences in transcript abundance of many genes involved in energy metabolism, particularly photosynthesis and photorespiration. Droughted grapevines appear to have a higher demand than non-stressed plants to detoxify free radicals (reactive oxygen species), and to cope with photoinhibition. Results of these defence strategies accumulate in berries, during the ripening period, and are at the base of grape quality. Berry metabolites accumulated in several cultivars, as a response of controlled levels of water stress to the grapevine, are shown. Berry (skin, pulp and seed) phenolic fractions and flavours are reviewed and linked to perturbations of their molecular pathways, when known.
Physiological, molecular and metabolic peculiarities genotype-specific are underlined.
Future perspectives of research on the reviewed topic are proposed, as focused on the interrelationship between ABA metabolism and molecular aspects of water control (aquaporins).
... A common feature of glycosylated plant secondary metabolites is that they are glucosides [13]. Based on the results obtained using β-D-glucosidase, it can be postulated that the kava lactone-yielding precursors are indeed β-D-glucosides. ...
This investigation has shown that the highly biologically active kava lactones, specifically those of desmethoxyyangonin, yangonin and kavain, exist in ''locked-up'' reserve forms. These important lactones can be regenerated from the totally delactoned polar residues when subjected to reflux at various pHs. The percentage of desmethoxyyangonin, yangonin and kavain regenerated from the same quantity of delactoned residue differed with the pH of the solution. Furthermore, treatment of the delactoned residue with β-D-glucosidase enzyme regenerated desmethoxyyangonin, yangonin and kavain in a pattern similar to that obtained under reflux at pH 5 and 8. These observations, when taken together with the outcome of the control experiment, suggest the presence of sugar bound kava lactone precursors in the delactoned residue.
... b-Glucosidase from Endozym b-split was selected for this experiment since it was the most stable and least inhibited the enzyme among the different b-glucosidases tested (35). The pNPG concentration was set at 0.12 mM, based on the values of the concentration of natural glycosides in wine (12,41,42). The pNP concentration at the reactor outlet was determined by HPLC. ...
Enzyme activity and stability in a membrane reactor for wine aroma enhancement can be higher than when the enzyme is present in a free state since the catalyst would only be in contact with the low molecular mass components of this beverage. To test this hypothesis,
the activity and stability of two commercial β-glucosidases were measured in the presence of Tannat wine and of its low molecular mass fraction (
... It is well known that a significant part of flavour remains as odourless glycosylated precursors in newly made wine that are not hydrolysed during ethanol fermentation. These odourless precursors containing aroma aglycones are not directly accessible to the olfactory mucosa, but may greatly affect wine quality after hydrolysis (Williams et al., 1995;McMahon et al., 1999). The hydrolysis of odourless precursors could be achieved through chemical or enzymatic treatment during winemaking. ...
β-D-glucosidase (βG) is one of the most interesting glycosidases for the hydrolysis of glycoconjugated precursors to release active aromatic compounds in musts and wines. Oenococcus oeni strains SD-2a and 31MBR are widely used in Chinese wines to reduce the acidity. In the present study, the βG activity of the two strains was localised and partially characterised using synthetic substrate. The activity occurred in whole cells, sonication supernatants and debris, but not in the culture supernatants for both strains. Whole cells of strain SD-2a possessed greater βG activity, while strain 31MBR showed higher enzyme activity in the sonication supernatants. Strain 31MBR exhibited higher total enzyme activity than strain SD-2a. The optimum temperatures for βG from the two strains were 40°C at pH 3.5 and 50°C at pH 5.0, respectively. Ethanol at low concentrations had a positive effect on βG activity in both strains, while a wine-like pH (3.5) decreased the enzyme activity to a great extent. Whole cells of strain SD-2a showed the highest activity among all samples tested under wine-like conditions. Thus, strain SD-2a proved to have potential for aroma improvement in winemaking.
... Not only monomeric polyphenols are released under acidic conditions but also the sugar moieties from glycosides may be cleaved. The original glycosyl-glucose assay by Williams et al. (1995) was primarily developed for the determination of glycosidically bound aroma precursors but may also be applied for the determination of anthocyanins or other flavonoid glucosides. ...
Polyphenols are a chemically diverse group of secondary metabolites that occur ubiquitously in plants. As a result of their pronounced structural diversity and hence their greatly differing chemical and physical properties, their analysis has proved to be challenging. In fruits and fruit-derived products, phenolic compounds are characterized and quantified for various reasons, for example, to determine the profile of potentially health-promoting bioactive compounds or for authentication purposes. While spectrophotometric methods are fast and inexpensive, they are non-specific and tend to overestimate the polyphenol content. In contrast, chromatographic techniques such as (U)HPLC, especially when combined with diode array and mass spectrometric detection, allow the characterization and quantification of individual compounds and are considered the method of choice nowadays. This contribution summarizes the most important publications including reviews on the analysis of phenolic compounds in fruits.
... Recently, some native Saccharomyces and non-Saccharomyces strains were identified that show glycosidase activity in an escullin solid medium [93]. This technique directly correlates with the GG determination method that measures their enzymatic hydrolysis of glycosylated compounds in grape must [94]. The glycosidic activity related to S. cerevisiae has been proven in Riesling and Chardonnay musts [95,96], and is weakly sensitive to the presence of sugar, but its action is very reduced due to must and wine pH [79,97,98]. ...
Terpenoids, which are typical components of the essential oils of flowers and fruits, are also present as free and glycosylated conjugates amongst the secondary metabolites of wine grape varieties of Vitis vinifera. Hence, when these compounds are present in wine, they are considered to originate from the grapes and not from fermentation. However, the biosynthesis of monoterpenes by Saccharomyces cerevisiae in the absence of grape derived precursors was shown recently to be of de novo origin in wine yeast strains. The contribution of yeast and bacterial fermentation metabolites to the aromatic profile of wine is well documented. However, the biotechnological application of this knowledge is still rather limited and often contradictory. Redox conditions, size of inoculums, temperatures of fermentation, osmotic pressure and the medium nutritional content can profoundly affect the profile of yeast and bacterial metabolites produced or their biotransformation capacity in wine. Results obtained in the last decades in relation to microbial micrometabolism of aroma compounds measured with more sophisticated GC-MS methods are discussed in relation to the known terpenoid biosynthetic pathways and wine composition. Further development of metabolic footprinting techniques for the discrimination of wine quality must be one of the main challenges for wine biotechnologists in the near future.
... Wine glycosides were extracted following a procedure described by Gunata et al. (1985) and Williams et al. (1995) by adsorbing them selectively on Amberlite XAD-2. The column (80 mm × 0.6 mm i.d.) was pre-treated six times with 10 mL methanol and six times with 10 mL diethyl ether, and then washed six times with 10 mL water. ...
Commercial preparations with glycosidase activities are used to enhance wine aroma, but they are not extensively characterized. The aim of this work was to study the effect of three enzymes on aroma improvement in Tannat red wine. After the selection of the mostappropriate enzyme for further testing, its effectiveness on the hydrolysis of the total glycosides present in Tannat wine was measured. The three preparations showed high â-glucosidase and á-arabinosidase activities (in the range of 10 to 174 U/mL or U/g), but very low levels of á-rhamnosidase (less than 1 U/mL). The â-glucosidases studied remained active in the presence of Tannat wine. The selected enzyme, Endozym â-split, supplemented with á-rhamnosidase, resulted in almost 30% hydrolysis of the glycosides in Tannat wine, when added at a concentration higher than that recommended by the manufacturers. A sensory evaluation showed that the enzyme-treated wines were significantly different from the controls, suggesting that at least a part of the hydrolyzed glycosides in the Tannat wine were aroma precursors. However, it cannot be assumed that all commercial enzymes would be effective in hydrolyzing aroma precursors just because they show glycosidase activities. Higher concentrations of Endozym â-split than that recommended by the manufacturer are necessary to reach an appreciable level of glycoside hydrolysis. Supplementation of Endozym â-split with á-rhamnosidase is recommended in this enzyme - wine system for the greater release of the aroma from the glycosidically-bound precursors.
... Methods such as those described above tend to be laborious and time-consuming. As hydrolysis of grape-derived glycosides produces an equimolar ratio of D-glucose and the aglycone, an enzyme assay quantifying glycosyl-glucose has been developed to estimate total concentration of bound secondary metabolites [40] as well as phenol-free glycoside concentration [44] in grapes, juices, and wines. Another rapid analytical technique described earlier by Dimitriadis and Williams [10] calls for hydrodistilling volatile fractions of free and bound volatiles and measuring the terpene content by colorimetry. ...
Changes in several physicochemical parameters of grape composition including pH, titratable acidity, soluble solids, weight, color, and phenolic content were examined for Gewürztraminer during ripening. Free and potentially volatile terpenes obtained by distillation were also assessed spectrophotometrically using an acidified vanillin assay and by gas chromatography-mass spectrometry (GC-MS). The colorimetric values of potentially volatile terpenes were estimated to account for nearly 84% of the bound terpenes, and the values of the free volatile terpenes reflected primarily the content of unsaturated aldehydes rather than the free terpenes. A procedure using selected ions specific to terpenes was developed to accelerate the analysis time of GC-MS chromatograms. Based on selected ion chromatograms, higher correlations were found for the bound terpene concentrations in Gewürztraminer vis-á-vis total skin phenolics, skin anthocyanins, and the traditional maturity indices of soluble solids and titratable acidity as compared to free terpene content.
... Berry skin thickness was determined by peeling 50 berries per treatment and measuring berry weight, berry diameter and berry skin weight. Measurements of bound glycosidic secondary metabolites were conducted according to the method of Williams et al. (1995) with some modifications (Iland et al. 1996;Werwitzke, 2003). Wines were made in 50 L lots in the experimental winery with fruit of each treatment. ...
The effects of UV-radiation on grapevine leaf and fruit physiology under field conditions were investigated. Selected portions of the light spectrum (within the UV wavelengths) were attenuated with polyester and di-and tri-acetate films. The entire canopy or parts thereof were covered with these films during berry development. Berry skin pigment composition was determined using a non-destructive spectrophotometric technique. There was a strong UV-induced shift towards the formation of red and brown pigment components without affecting sugar levels. Chlorophyll degradation in the leaves and berry skins occurred more rapidly in the high UV-radiation treatments. Exposure to UV-B radiation increased both the concentration of total bound glycosidic secondary metabolites and phenolics. There were some noticeable effects on the aromatic expression in the resulting wines.
Grape maturity at harvest strongly affects wine quality, and therefore determining an adequate strategy for harvest date selection based on objective quality indicators is a key issue in producing high-quality and premium wines. In white wine technology, grape quality is usually assessed by chemical composition with a particular interest in volatile content and profile.
In this sense, vineyard management is of primary importance together with the choice of harvest time. In fact, the basis of wine characteristics is intrinsically confined in the grape quality, and the wide diversity in white wine grape chemical composition is of major technological importance, as each cultivar requires dedicated enological adaptation of the winemaking technique.
Abstract : Cognac spirit have a complex composition in aroma compounds which contributes to the product’s typical features perceived by the consumer. These compounds have different origins: they could come from grape musts, can be formed during fermentation, or be produced during distillation. The formation of compounds during distillation remains little understood, making this process hard to control regarding the specific aroma generated by heating during distillation. However, the “Charentaise distillation” of Cognac spirit is a traditional process well described in terms of equipment and operation by professionals. All the aroma compounds found in Cognac spirit freshly distilled results from the combination of several factors occurring before or during distillation. Indeed, the wine’s characteristics (acidity, alcohol content, aroma arising from yeast fermentation…), the method and the period of distillation strongly affect the final aroma composition of freshly distilled spirit. This work focus on the distillation process and in particular on aroma specifically produced by reaction during heating, besides aroma enrichment in final product through volatility principle. The “Charentaise distillation” method to obtain Cognac spirit is performed in two phases: the first step consists in heating the wine introduced in the boiler in order to obtain a distillate called “brouillis”. This brouillis is brought back to the boiler for a second distillation (second step) to obtain the spirit that will undergo a slow maturation in an oak barrel. The double distillation takes place under thermal conditions that could promote the generation of aroma compounds. The aim of this study is to identify these aroma compounds formed during distillation and formulate hypothesis regarding the reactions at the origin of their formation. To study the formation of these compounds at large-scale, a pot-still (alembic) with a capacity of 25 hectoliters have been made available, on which temperature sensors and a density meter have been installed. These devices allow a continuous follow-up on the evolution of these parameters. Sampling during distillation have been performed on the distillate and inside the boiler. The analysis on those samples allowed to perform a mass balance and point out several types of aroma compounds whose quantities have strongly increased during the distillation process. These compounds can be distinguished by their chemical family. Thus, two aldehydes: isobutanal (having a flowery odour) and 2-methylbutanal (having a chocolate odour) are mainly formed during distillation, coming certainly from a Strecker degradation. Moreover, two aromatic compounds, from norisoprenoids family: 1,1,6-trimethyldihydronaphtalene and 1-(2,3,6-trimethylphenyl)-3-buten-2-one commonly called TDN and TMPBE respectively are formed as well. TDN possesses notes of hydrocarbons whereas TMPBE has violet notes. Both are certainly present in the wine in their glycosidic form, and this issue will be studied in detail. The whole results suggest that part of aroma compounds found in Cognac spirit is formed during distillation due to chemical reactivity phenomena to be further studied in depth in our work.
Cognac wine spirit has a complex composition in volatile compounds which contribute to its organoleptic profile. This work focused on the batch distillation process and, in particular, on volatile compounds specifically produced by chemical reactions during the distillation of Cognac wine spirit, traditionally conducted in two steps with charentais pot stills. The aim of this study was to characterize these volatile compounds formed during distillation. Sampling has been performed on the distillates and inside the boiler during a typical Cognac distillation. The analysis of these samples allowed to perform a mass balance and to point out several types of volatile compounds whose quantities strongly increased during the distillation process. These compounds were distinguished by their chemical family. It has been found that the first distillation step was decisive for the formation of volatile compounds. Moreover, 2 esters, 3 aldehydes, 12 norisoprenoids and 3 terpenes were shown to be generated during the process. These results suggest that some volatile compounds found in Cognac spirit are formed during distillation due to chemical reactions induced by high temperature. These findings give important indications to professional distillers in order to enhance the product’s quality.
The aroma of La Mancha Malbec red wines over four consecutive vintages was characterized by chemical and sensory analysis. Solid phase extraction (SPE) and gas chromatography–mass spectrometry (GC–MS) were used to isolate and analyze free volatile compounds. Quantitative Descriptive Sensory Analysis (QDA) was carried out to characterize the sensory aroma profile. A total of 79 free volatile compounds were identified and quantified in the wines over these four vintages. Volatile aroma compounds were classified into seven aromatic series and their odour activity values were calculated in order to determine the aroma impact compounds in these wines. The aroma sensory profile of these wines was characterized by red fruit, fresh, prune, liquorice, clove, caramel, leather, tobacco and coffee aromas. This study provides a complete aroma characterization of La Mancha Malbec red wines and it is proposed that these wines can be considered as an alternative to wines from traditional grape varieties of this region.
Pioneering investigations into precursors to fruity and floral flavors established the importance of terpenoid and C13-norisoprenoid glycosides to the flavor of aromatic wines. Nowadays flavor precursors in grapes and wine are known to be structurally diverse, encompassing glycosides; amino acid conjugates; odorless volatiles; hydroxycinnamic acids and many others. Flavor precursors mainly originate in the grape berry, but also from oak or other materials involved in winemaking. Flavors are released from precursors during crushing and subsequent production steps by enzymatic and non-enzymatic transformations, via microbial glycosidases; esterases; C-S lyases and decarboxylases; and through acid catalysed hydrolysis and chemical rearrangements. Flavors can also be liberated from glycosides and amino acid conjugates by oral microbiota. Hence, it is increasingly likely that flavor precursors contribute to retronasal aroma formation through in-mouth release during consumption, prompting a shift in focus from identifying aroma precursors in grapes to understanding aroma precursors present in bottled wine.
The institute Agroscope tried the early defoliation on Doral (cv. Chardonnay x Chasselas) at the experimental vineyard of Changins (VD, Switzerland) to evaluate the consequences and risks of this technique on the vine physiology, grape composition and wine quality. An intensive defoliation before berry set induced up to 30 % yield reduction. Leaf removal, even early and intensive, had no consequences neither on the vine sustainability in terms of bud fruitfulness and vigour, nor on the wine organoleptic profiles. Under these experimental conditions, an early defoliation of the vine at flowering (six basal leaves + lateral shoots) was a promising practice to regulate the yield without subsequent cluster thinning.
The major aroma components in grapes and wine include free volatile compounds and glycosidic nonvolatile compounds. The latter group of compounds is more than 10 times abundant of the former, and constitutes a big aroma reserve in grapes and wine. This review summarizes the research results obtained recently for the identification of aroma glycosides in grapes and wine, including grape glycoside structures, differences in aroma glycosides among grape varieties, hydrolysis mechanisms, and the factors that influence them. It also presents the analytical techniques used to identify the glycosidic aroma precursors. The operational strategies, challenges, and improvements of each step encountered in the analysis of glycosidic aroma precursors are described. This review intends to provide a convenient reference for researchers interested in the methods used for the determination of the aroma glucosides composition and the recognition of their chemical structures.
beta-Glucosidase (beta G, EC 3.2.1.21) is one of the most interesting glycosidases, especially for hydrolysis of glycoconjugated precursors, in musts and wines, and the release of active aromatic compounds. The aim of this work was to study the synergism between yeasts beta-glucosidase activity and fungal beta-glucosidase activity. An increase in concentrations of volatile terpenes and norisoprenoids was observed when the selected yeasts were associated with enzymes preparation with beta-glucosidase activity.
A method to study the glycosidically bound fractions in red grape juice was developed. Bound fractions were fractionated by solid-liquid chromatography on LiChroprep RP-18. The release of free aglycones was achieved by acid hydrolysis. In a preliminary approach the acid hydrolysis was performed at pH 1.0 and pH 3.0 levels. The pH 3.0 was selected in this study mainly due to its similarity with the pH levels that occur naturally in juices and grapes. Nine extractions of the same juice sample were carried out to study the repeatability of the method at pH 3.0. All the extracts were analysed by GC-MS and GC-FID. The repeatability found in the various quantified components in all extracts of the bound fraction of juice is expressed by their coefficient of variation, which varied in the range between 11.5% and 24.7%. Four aglycones, trans-furan linalool oxide, cis-furan linalool oxide, vitispirane, and beta-damascenone were quantified after pH 3.0 hydrolysis.
The terpenoids are a major class of natural products with a range of functions in plants. In the grape, monoterpenes, sesquiterpenes and C13-norisoprenoids are present either in a free volatile form, or bound to sugars and rendered non-volatile. Of the many terpenoids in grapes, only a relatively small number makes an important contribution to wine aroma. This review summarises new developments in understanding terpenoids, including the monoterpenes linalool, cis-rose oxide, 1,8-cineole and wine lactone; the sesquiterpene rotundone; and the C13-norisoprenoids β-damascenone, β-ionone, 1,1,6-trimethyl-1,2-dihydronaphthalene and (E)-1-(2,3,6-trimethylphenyl)buta-1,3-diene. Their origin, formation and behaviour during winemaking and ageing, and viticultural influences on their concentration, will be discussed, as well as their role in different wine styles.
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.
Triple Quadrupole The Q-TOF The MALDI TOF–TOF References
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.
Due to their attractive aroma properties often combined with low odor thresholds carotenoid-derived aroma compounds (synonyms: norisoprenoids/norterpenoids) are highly esteemed by the flavor and fragrance industry. Despite considerable efforts in the understanding of the formation of carotenoid-derived flavor compounds from non-volatile precursors including the stereodifferentiation of an increasing number of aroma-relevant candidates, still little is known about the initial steps of carotenoid biodegradation. This chapter gives a survey of the present knowledge in the biogenesis of norisoprenoid compounds and outlines possible ways for their biotechnological production.
In this review an original and unique approach was undertaken to unite the notions "heterocycles" and "wine principles." Indeed, it is astonishing that natural wines contain numerous heterocyclic principles in varying quantities (as low as nanograms!) that contribute to flavor, smell, taste, and aftertaste (" finish" ) sensations, all of which are characteristic of the different grape types. During aging and maturation of the wines in barrels and bottles, manifold additional heterocycles are formed or extracted. The odor threshold plays an important role in all cases, which is ultimately dependent on the chirality centers of the isomers involved in aroma. These heterocyclic classes are manifold: O-heterocycles (lactones, furans, flavones, carbohydrates), O-glucosides of terpenes, tannins, flavones, procyanidins, heterocyclic polyphenols with significant benefits to human health, S-heterocycles stemming from yeast metabolism and possessing strong organoleptic properties, N-heterocycles (pyrroles, pyrimidines, pyrazines, the latter constituents having a typical green pepper flavor and aroma). Finally, the role of fungicides and pesticides in wine is 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%.
Brettanomyces bruxellensis and lactic acid bacteria are common microorganisms capable of modifying wine aroma and flavor. The activity of β-glucosidase against p-nitrophenyl-β-D-glucopyranoside was determined in a model system for 14 strains of Brettanomyces bruxellensis yeast and 9 strains of lactic acid bacteria (Oenococcus oeni). All Brettanomyces strains and 7 Oenococcus strains exhibited enzymatic activity against this substrate. B. bruxellensis β-glucosidase activity was primarily intracellular; O. oeni showed some extracellular activity. Strains showing activity greater than 1000 nmole mL-1 g dry cell mass-1 24 hr-1 for Brettanomyces, or 100 nmole mL-1 g dry cell mass-1 24 hr-1 for Oenococcus, were evaluated for their effect on native Viognier grape glycosides. Neither genus was active on Viognier grape glycosides.
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.
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.
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.
This book represents another attempt to educate analytical chemists in the use of simple statistics. It is an easy-to-read overview of the topics with which every analytical chemist should be familiar. The early chapter on errors in analysis, significance testing, and quality control are well written. A good introduction to these topics is provided in the first 100 pages. Chapter 6 on nonparametric methods is quite useful; it provides justification and incentive to learn and use these methods. Chapter 7 covers very large and useful topics such as experimental design, optimization, and pattern recognition. Fractional factorial designs and principle component analysis are only mentioned, not discussed in detail. This book can be easily read and can heighten one's awareness of many important topics from statistics to chemometrics. Because it comes complete with a number of good exercises (no programs), the author also recommend it as a textbook for a short course.
Glycosidic derivatives of monoterpene flavourants of grapes and wines can be preparatively isolated by selective retention on a C18-bonded reversed-phase adsorbent. These components can thus be concentrated by a factor of 20,000 in a single chromatographic step. Class separation of monoterpene glycosides at different oxidation levels can also be achieved on the reversed-phase adsorbent.Teh process has also led to the discovery of precursors of 2-phenylethanol, benzyl alcohol, damascenone, vitispirane and 1,1,6-trimethyl-1,2-dihydronaphthalene. Additionally, many other related nor-isoprenoid compounds not previously known in grapes have been observed.
A simple enzymatic method is described for the determination of stevioside in Stevia rebaudiana. The method is based on the hydrolysis of stevioside with crude hesperidinase. The reaction is followed by monitoring the production of glucose with a glucose oxidase-peroxidase-2, 2′-azino-di-(3-ethylbenzothiazoline-6-sulfonic acid) system. The results for the stevioside content in S. rebaudiana leaves correlate with those obtained by other methods. The stevioside content in S. rebaudiana plants showed large variation.
A method of extraction and determination of free and glycosidically bound terpenols and of benzyl and 2-phenylethyl alcohols is suggested. The extraction was carried out by adsorbing these compounds on a non-ionic resin, Amberlite XAD-2, and then elution with various selective solvents. Free forms were directly determined by gas chromatography; glycosidically bound forms were first enzymatically hydrolysed to release aglycones. This method was applied to a number of mature grape varieties. The levels of glycosidically bound terpenols and aromatic alcohols were always high, usually much higher than the free forms. The varieties can be classified in two groups: those rich in free and bounds forms which give aromatic wines (Muscat varieties and Gewürztraminer), and those which contain small amounts of these compounds and which give more neutral wines.
The factors affecting the stability, hydrolysis, reduction, acetylation, quantitation, and identification of the neutral sugars from vegetable fiber preparations have been studied critically and optimized. The recommended method offers a consolidation of the recent modifications of the alditol acetate procedure for the estimation of neutral sugars. The recovery of the sugars was tested by glc and ion-exchange chromatography. Also, the modified carbazole method of Bitter and Muir was adapted to make it applicable for the estimation of uronic acid content of fiber because uronic acid cannot be estimated quantitatively by the acetylation procedure. It is emphasized that the proposed method is applicable only to highly purified fiber preparations which are free of coprecipitated intracellular compounds. Also, the levels of pentoses and hexoses in the fiber must be well defined and a suitable correction made for their interference in the assay.
Synthetic monoterpene and aromatic beta-D-glucopyranosides, beta-rutinosides and 6-O-(alpha-L-arabinofuranosyl)-beta-D-glucopyranosides and their corresponding alcohols, diluted in a synthetic solution imitating wine, were isolated and separated by selective retention on Amberlite XAD-2. The corresponding recoveries and the conditions for the direct determination of these glycosides by gas chromatography and gas chromatography-mass spectrometry after derivatization were determined. Trifluoroacetylation gave the best results but trimethylsilylation provided complementary results. The separation of some diastereoisomeric monoterpene glycosides was also examined.
Free and glycosidically bound terpenes of five Vitis vinifera grape cultivars (muscat of Alexandria, muscat of Frontignan, muscat of Hamburg, muscat Ottonel and Gewürztraminer) were investigated. The free and bound fractions were separated by selective retention on Amberlite XAD-2 resin. The glycosidic fractions were analysed by gas chromatography and gas chromatography-mass spectrometry using either enzymic hydrolysis and subsequent analysis of the released aglycones or trimethylsilyl (TMS) and trifluoroacetyl derivatives. The known monoterpenyl, benzyl and 2-phenylethyl beta-D-glucopyranosides, beta-rutinosides, 6-O-alpha-L-arabinofuranosyl-beta-D-glucopyranosides and 6-O-beta-D-apiofuranosyl-beta-D-glucopyranosides were determined. A number of other glycosides were detected and the structures of some of them, mainly apiosylglucosides and glucosides with aglycones in higher oxidation state than linalol, were tentatively identified using the mass spectra of their TMS and TFA derivatives and the results obtained from the analysis of their aglycones.
A survey of known and of recently isolated constituents from Ginkgo leaves is given. The structures of flavonoids and terpene lactones which are considered to be the active compounds as well as their qualitative and quantitative determination in Ginkgo leaves and phytomedicines are presented. In the case of flavonoid analysis three selective methods worked out in our laboratories are described. The quality control of terpene lactones is discussed on the basis of a recently published paper. Finally, the standardization methods used for the quality control of Ginkgo preparations as well as the question as to whether or not phytomedicine generics--so called "phytogenerics"--exist, is discussed.
Analytical methods for monoterpene glycosides in grape and wine. 11. Qualitative and quantitative determination of monoterpene glycosides in grape Hydrolytic flavor release in fruit and wines through hydrolysis of non-volatile precursors. In Flavor Science Sensible Principles and Techniques
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The glycosides of oxygenated lower terpenes in plant leaves
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Measure of potential wine quality by analysis of grape glycosides
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Use of CIS reversed-phase liquid chromatography for the isolation of monoterpene glycosides and nor-isoprenoid precursors from grape juice and wines Hydrolytic flavor release from non-volatile precursors in fruits, wines and some other plant-derived foods
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Wilson, B.; Massy-Westropp, R. A. Use of CIS reversed-phase liquid chromatography for the isolation of monoterpene glycosides and nor-isoprenoid precursors from grape juice and wines. J. Chromatogr. 1982, Williams, P. J.; Sefton, M. A.; Marinos, V. A. Hydrolytic flavor release from non-volatile precursors in fruits, wines and some other plant-derived foods. In Recent Developments In Flavor And Fragrance Chemistry, 3rd Haarmann And Reimer International Symposium, Kyoto, Japan; VCH: Wein-heim, 1993; pp 283-290. 235,471-480.
naringin (Apin Chemicals Ltd, Oxford-shire
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Karlsruhe, Germany), naringin (Apin Chemicals Ltd, Oxford-shire, U.K.), and phloridzin (Calbiochem).