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The volatile composition of grapes has a direct impact on the final aromatic composition of wine and plays a crucial role in determining its quality. Various factors, such as agronomic practices, climatic conditions or grape variety, can influence the volatile composition of grape juices. This study aimed to determine the influence of three doses of urea, applied at two different phenological stages (pre-veraison and veraison), on the volatile composition of Tempranillo musts, during two consecutive seasons. The urea application did not have an impact on the yield of the vineyard or the general parameters of the Tempranillo must. However, the three different concentrations of urea modified the volatile composition. Specifically, the higher concentration of urea improved the terpenoids, C13 norisoprenoids, and benzenoid compounds in grape juice. Additionally, when urea treatments were applied at pre-veraison, terpenoids, C13 norisoprenoids, esters, and benzenoid compounds were improved in Tempranillo must. However, the weather was an important factor influencing the volatile compounds in Tempranillo musts. Consequently, foliar applications of urea could be an interesting viticulture practice in order to enhance the volatile compounds in Tempranillo musts.

Selective enhancement of wine aroma was achieved using a broad spectrum of exogenous glycosidases. Eight different enzyme preparations were added to Verdejo wine, resulting in an increase in the levels of varietal volatile compounds compared to the control wine after 15 days of treatment. The enzyme preparations studied were robust under winemaking conditions (sulfur dioxide, reducing sugars, and alcohol content), and no inhibition of β-glucosidase activity was observed. Significant differences were detected in four individual terpenes (α-terpineol, terpinen-4-ol, α-pinene, and citronellal) and benzyl alcohol in all the treated wines compared to the control wine, contributing to the final wine to varying degrees. In addition, a significant increase in the other aromatic compounds was observed, which showed different patterns depending on the enzyme preparation that was tested. The principal component analysis of the data revealed the possibility of modulating the different aromatic profiles of the final wines depending on the enzyme preparation used. Taking these results into account, enhancement of the floral, balsamic, and/or fruity notes of wines is possible by using a suitable commercial enzyme preparation. [ABSTRACT FROM AUTHOR]

Varietal thiol concentration in wine is influenced by numerous factors, of which grape variety and winemaking practices are often highlighted as the most important. Therefore, the aim of this work was to study the effects of grape clone and yeast strain (Saccharomyces and non-Saccharomyces) on the varietal thiols concentrations and sensory characteristics of Graševina (Vitis vinifera L.) white wines. Two grape clones were evaluated (OB-412 and OB-445) along with three different commercial yeast strains (Saccharomyces cerevisiae Lalvin Sensy and Sauvy, and Metschnikowia pulcherrima Flavia). The results showed that the concentration of varietal thiols in Graševina wines amounted up to a total of 226 ng/L. The clone OB-412 was characterized by its significantly higher concentrations, especially of 3-sulfanylhexanol (3SH) and 3-sulfanylhexyl acetate (3SHA). Moreover, alcoholic fermentation with pure S. cerevisiae Sauvy yeasts generally resulted in higher thiol concentrations, while sequential fermentation involving M. pulcherrima positively affected only the 4-methyl-4-sulfanyl-pentan-2-one (4MSP) concentration. Finally, sensory analysis showed that fermentation with pure S. cerevisiae Sauvy yeast also produced more desirable wines. The results suggest that clonal, and especially yeast strain, selections are important modulators of the aroma and sensory properties of wine. [ABSTRACT FROM AUTHOR]

Selective enhancement of wine aroma was achieved using a broad spectrum of exogenous glycosidases. Eight different enzyme preparations were added to Verdejo wine, resulting in an increase in the levels of varietal volatile compounds compared to the control wine after 15 days of treatment. The enzyme preparations studied were robust under winemaking conditions (sulfur dioxide, reducing sugars, and alcohol content), and no inhibition of β-glucosidase activity was observed. Significant differences were detected in four individual terpenes (α-terpineol, terpinen-4-ol, α-pinene, and citronellal) and benzyl alcohol in all the treated wines compared to the control wine, contributing to the final wine to varying degrees. In addition, a significant increase in the other aromatic compounds was observed, which showed different patterns depending on the enzyme preparation that was tested. The principal component analysis of the data revealed the possibility of modulating the different aromatic profiles of the final wines depending on the enzyme preparation used. Taking these results into account, enhancement of the floral, balsamic, and/or fruity notes of wines is possible by using a suitable commercial enzyme preparation.

β‐Glucosidase is a key enzyme that hydrolyzes nonvolatile glycosylated precursors of aroma compounds and enhances the organoleptic quality of wines. In this study, a novel β‐glucosidase from Hanseniaspora uvarum Yun268 was localized, purified, and characterized. Results indicated that β‐glucosidase activity was mainly distributed within the cells. After purification via ammonium sulfate precipitation combined with chromatography, β‐glucosidase specific activity increased 8.36 times, and the activity recovery was 56.90%. The enzyme had a molecular mass of 74.22 kDa. It has a Michaelis constant (Km) of 0.65 mmol/L, and a maximum velocity (Vmax) of 5.1 nmol/min under optimum conditions; and Km of 0.94 mmol/L, and Vmax of 2.8 nmol/min under typical winemaking conditions. It exhibited the highest activity at 50°C and pH 5.0 and was stable at a temperature range of 20–80°C and pH range of 3.0–8.0. The enzyme has good tolerance to Fe3+, especially maintaining 93.68% of its activity with 10 mmol/L of Fe3+. Ethanol (<20%) and glucose (<150 g/L) inhibited its activity only slightly. Therefore, β‐glucosidase from H. uvarum Yun268 has excellent biochemical properties and a good application potential in winemaking. Practical Application: Winemaking is a biotechnological process in which exogenous β‐glucosidase is used to overcome the deficiency of endogenous β‐glucosidase activity in grapes. By localizing, purifying, and characterizing of β‐glucosidase from Hanseniaspora uvarum Yun268, it is expected to reveal its physical and chemical characteristics to evaluate its oenological properties in winemaking. The results may provide the basis for promoting the release of varietal aroma and improving wine sensory quality in the wine industry. [ABSTRACT FROM AUTHOR]

Varietal thiol concentration in wine is influenced by numerous factors, of which grape variety and winemaking practices are often highlighted as the most important. Therefore, the aim of this work was to study the effects of grape clone and yeast strain (Saccharomyces and non-Saccharomyces) on the varietal thiols concentrations and sensory characteristics of Graševina (Vitis vinifera L.) white wines. Two grape clones were evaluated (OB-412 and OB-445) along with three different commercial yeast strains (Saccharomyces cerevisiae Lalvin Sensy and Sauvy, and Metschnikowia pulcherrima Flavia). The results showed that the concentration of varietal thiols in Graševina wines amounted up to a total of 226 ng/L. The clone OB-412 was characterized by its significantly higher concentrations, especially of 3-sulfanylhexanol (3SH) and 3-sulfanylhexyl acetate (3SHA). Moreover, alcoholic fermentation with pure S. cerevisiae Sauvy yeasts generally resulted in higher thiol concentrations, while sequential fermentation involving M. pulcherrima positively affected only the 4-methyl-4-sulfanyl-pentan-2-one (4MSP) concentration. Finally, sensory analysis showed that fermentation with pure S. cerevisiae Sauvy yeast also produced more desirable wines. The results suggest that clonal, and especially yeast strain, selections are important modulators of the aroma and sensory properties of wine.

This study aimed at determining the changes induced by two S. cerevisiae strains, (IONYS wf™ and Lalvin ICV D254™) on the sensory and chemical aroma profiles of Tempranillo wine, after fermentation and after ageing. The 64 aroma molecules determined were grouped attending to sensory and chemical similarity into 17 aroma vectors. Sensory studies included a sorting task and a descriptive analysis by flash profile with a trained panel. Results revealed that, even if ageing is the dominant factor, the strain of yeast introduces significant and consistent differences, both in sensory and aroma vector profiles (11 out of 17 affected). Wines made with D254 contained higher levels of ethyl esters, acetic acid, cinnamates and ethyl acetate and lower levels of linear fatty acids, β-damascenone, acetaldehyde, higher alcohols and lactones than those made with IONYS. The first profile was related to black and fresh fruit notes, while the second to white and compote fruits.

Dehydration or drying of grapes is one of the most important steps in the production of Croatian traditional dessert wine Prošek. The natural sun drying of grapes is the traditionally used method in Prošek production. Alternative methods, such as dehydration under controlled conditions, have been studied as safer and faster methods than the traditional sun drying but without precise knowledge of the effect on volatile compounds. The objective of this work was to study how dehydration of grapes carried out in a greenhouse and an environmentally controlled chamber impacts on the free and glycosidically bound volatile compounds of native grape cv. 'Maraština'. The 36 volatile compounds were identified and quantified using headspace solid-phase micro extraction coupled with gas chromatography-mass spectrophotometry (HS-SPME-GC/MS). The results showed that the aroma profile of dehydrated grapes was significantly different from that of fresh grapes. Regarding free forms, significant increases in the concentration of 2-methyl-1-propanol, 1-butanol, 2-hexen-1-ol, 1-hexanol, ethyl hexanoate, hexyl acetate, o-cymene, linalool oxide, and terpinen-4-ol and geraniol were found in greenhouse-dried grapes, whereas increases in cis-limonene-epoxide, trans-limonene epoxide, and γ-hexalactone were higher in chamber-dried grapes compared to greenhouse-dried grapes. Glycosidically bound forms of o-cymene, linalool oxide, linalool, and terpinen-4-ol were increased in both types of drying, whereas β-damascenone was increased only in greenhouse-dried grapes. [ABSTRACT FROM AUTHOR]

The potential of pulsed electric fields (PEF) for improving polyphenol extraction, decreasing maceration and increasing aroma compounds in the course of the winemaking process were investigated. Twelve tons of Garnacha grapes were processed at a flow rate of 2500 kgh-1, and wines obtained from untreated and PEF-treated (4.0kV cm-1) grapes after 3 and 6 days of maceration were compared. The highest values of total anthocyanin, total polyphenolic, tannin content, and color intensity were obtained with PEF-treated grapes as well as when the maceration period was extended. The higher tannin concentration observed in PEF- treated wines was a consequence of a higher degree of extraction of tannins located in the grape skins rather than in the seeds. Finally, PEF contributed to the extraction of some individual precursors positive for aroma. These results, obtained at conditions very close to requirements at industrial scale, may encourage the adoption of PEF technology by wineries. [ABSTRACT FROM AUTHOR]

Nitrogen is an important component that affects grapevine growth and the formation of flavor-associated volatile chemicals in grape berries. Dynamic changes in amino acids and aroma compounds in Chardonnay grape berry preharvest treated with different doses of salicylic acid (SA) at onset and one week later of veraison stage were evaluated. Exogenous 1- or 3-mM SA application significantly increased the content of total soluble solid and titratable acid in grapes, while 5 mM SA tended to decrease their levels. Compared with the control, the concentration of yeast assimilable nitrogen were 9.3% and 14.6% higher in 3 mM SA-treated grapes in 2021 and 2022, respectively. Preharvest 3 mM SA treatment efficiently enhanced the accumulation of nine amino acids, including tryptophan, phenylalanine, tyrosine, aspartic acid, lysine, asparagine, valine, isoleucine and histidine, as well as the concentration of total amino acid with and without proline in the two grape vintages. Higher concentrations of primary phenylalanine-derivatives and terpenoids and lower levels of C 6 compounds in grapes treated with 3 mM SA were observed during the 2021–2022 season. Overall, SA improved the quality of wine grape in a dose dependent manner, while the response of berries to SA treatment also showed effects of the vintage. [Display omitted] • Preharvest SA treatment improved the YAN content in Chardonnay grape during development. • More aromatic amino acids accumulated in grapes treated with 3 mM SA. • Phenylalanine-derived volatiles and terpenoids were upregulated by exogenous SA. • 3 mM SA treatment improves the quality traits of grape fruits. [ABSTRACT FROM AUTHOR]

Dehydration or drying of grapes is one of the most important steps in the production of Croatian traditional dessert wine Prošek. The natural sun drying of grapes is the traditionally used method in Prošek production. Alternative methods, such as dehydration under controlled conditions, have been studied as safer and faster methods than the traditional sun drying but without precise knowledge of the effect on volatile compounds. The objective of this work was to study how dehydration of grapes carried out in a greenhouse and an environmentally controlled chamber impacts on the free and glycosidically bound volatile compounds of native grape cv. ‘Maraština’. The 36 volatile compounds were identified and quantified using headspace solid-phase micro extraction coupled with gas chromatography-mass spectrophotometry (HS-SPME-GC/MS). The results showed that the aroma profile of dehydrated grapes was significantly different from that of fresh grapes. Regarding free forms, significant increases in the concentration of 2-methyl-1-propanol, 1-butanol, 2-hexen-1-ol, 1-hexanol, ethyl hexanoate, hexyl acetate, o-cymene, linalool oxide, and terpinen-4-ol and geraniol were found in greenhouse-dried grapes, whereas increases in cis-limonene-epoxide, trans-limonene epoxide, and γ-hexalactone were higher in chamber-dried grapes compared to greenhouse-dried grapes. Glycosidically bound forms of o-cymene, linalool oxide, linalool, and terpinen-4-ol were increased in both types of drying, whereas β-damascenone was increased only in greenhouse-dried grapes.

Selective enhancement of wine aroma was achieved using a broad spectrum of exogenous glycosidases. Eight different enzyme preparations were added to Verdejo wine, resulting in an increase in the levels of varietal volatile compounds compared to the control wine after 15 days of treatment. The enzyme preparations studied were robust under winemaking conditions (sulfur dioxide, reducing sugars, and alcohol content), and no inhibition of β-glucosidase activity was observed. Significant differences were detected in four individual terpenes (α-terpineol, terpinen-4-ol, α-pinene, and citronellal) and benzyl alcohol in all the treated wines compared to the control wine, contributing to the final wine to varying degrees. In addition, a significant increase in the other aromatic compounds was observed, which showed different patterns depending on the enzyme preparation that was tested. The principal component analysis of the data revealed the possibility of modulating the different aromatic profiles of the final wines depending on the enzyme preparation used. Taking these results into account, enhancement of the floral, balsamic, and/or fruity notes of wines is possible by using a suitable commercial enzyme preparation.

Hops are among the most important ingredients in beer that contribute to beer flavor. Consequently, novel types of hops have been bred and widely used worldwide. For example, the Sorachi Ace hop imparts characteristic varietal aromas, including woody, pine-like, citrus, dill-like, and lemongrass-like aromas, to the finished beer. In our previous study, the unique volatile compound geranic acid was significantly detected only in the test beer brewed with the Sorachi Ace hop; moreover, the coexistence of geranic acid and other hop-derived flavor compounds could result in the characteristic aroma of the Sorachi Ace beers. In this study, selected hop-derived flavor compounds, including geranic acid, were compared among 17 hop varieties. The geranic acid content in the Sorachi Ace hop was the highest among the studied hops. We also investigated the behavior of geranic acid and related flavor compounds throughout the fermentation process. The content of geranic acid was higher than those of the other compounds during fermentation. Next, we compared the concentrations of these compounds in kettle-, late-, and dry-hopped beers using Sorachi Ace hop. The results revealed that geranic acid remained at higher concentrations from the worts to finished beers despite the decrease in the content of other hop-derived flavor compounds as a result of evaporation and/or other factors during brewing. Further, geranic acid could remain at high levels in the test-brewed beers with Sorachi Ace hops because of its behavior as an acid throughout the brewing process, including during wort boiling and fermentation.

Pulsed electric field (PEF) processing of white grapes (cv. Garganega) after crushing was studied on pilot-plant scale, to investigate the effects of the treatment on must and wine composition, wine color and predisposition to browning, wine aroma compounds and extraction of aroma precursors from grapes. PEF pre-treatment of grapes did not change the must or wine basic composition, nor was it able to modify the evolution of alcoholic fermentation. By contrast, PEF produced an increase in total dry extract, wine color and total phenolics. Treatment corresponding to a total specific energy of 22 kJ kg −1 allowed more intense extraction of varietal aroma precursors without provoking excessive color evolution and extraction of phenolic compounds, apparently increasing the stability of wine towards oxidation. Due to the few papers available on this subject, PEF applications on white grapes should be optimized in further experiments. [ABSTRACT FROM AUTHOR]

An alternative to improve grape quality is the elicitor application to the vineyard due its implication to induce defense mechanisms involved in the synthesis of secondary metabolites. There are few studies about the influence of elicitors on grape volatile composition. The aim of this work was to investigate the influence of methyl jasmonate (MeJ) foliar application to Tempranillo grapevines on grape aroma composition over three consecutive vintages. In the first vintage, MeJ treatment improved p-cymene, methyl jasmonate, and hexanal synthesis, and degraded 2-hexen-1-ol acetate, (Z)-3-hexen-1-ol, and n -hexanol. In the second season, the content of several terpenes, β -damascenone, methyl jasmonate, esters, benzenoids and (Z)-3-hexen-1-ol was diminished after MeJ application. In the third vintage, the synthesis of several volatile compounds considered positive contributors for grape aroma was improved by MeJ application. In conclusion, the effect of MeJ foliar application on grape volatile content was mainly dependent on the vintage. [ABSTRACT FROM AUTHOR]

Recently, various technologies which utilise fermentation with skins have been developed for obtaining distinct white wines. This study first reports the dynamic changes of volatiles and phenols that occur during skin fermentation in white winemaking. Volatiles were analysed by solid-phase extraction (SPE), solid-phase microextraction (SPME) and gas chromatography (GC), and phenols by ultra-performance liquid chromatography (UPLC), both with mass spectrometric detection. Monoterpenols increased during the first 3 days of skin fermentation, after which certain glycosides decreased, but were higher than in control. The presence of skins reduced ho-trienol, β-damascenone, acids and esters. After a 1–3 days lag phase, skin fermentation caused a constant increase of most phenols. It was estimated that skin fermentation up to 1–3 days might be beneficial for monoterpenol varietal aroma, which should be re-evaluated through further studies. Longer durations promoted phenol extraction more strongly, which is possibly suitable for obtaining more distinct wines or blending components. [ABSTRACT FROM AUTHOR]

Dimethyl sulfide (DMS) is a sulfur containing volatile that enhances general fruity aroma and imparts aromatic notes in wine. The most important precursor of DMS is S- methylmethionine (SMM), which is synthesized by grapes and can be metabolized by the yeast S. cerevisiae during wine fermentation. Precursor molecules left after fermentation are chemically converted to DMS during wine maturation, meaning that wine DMS levels are determined by the amount of remaining precursors at bottling. To elucidate SMM metabolism in yeast we performed quantitative trait locus (QTL) mapping using a population of 130 F2-segregants obtained from a cross between two wine yeast strains, and we detected one major QTL explaining almost 30% of trait variation. Within the QTL, gene YLL058W and SMM transporter gene MMP1 were found to influence SMM metabolism, from which MMP1 has the bigger impact. We identified and characterized a variant coding for a truncated transporter with superior SMM preserving attributes. A population analysis with 85 yeast strains from different origins revealed a significant association of the variant to flor strains and minor occurrence in cheese and wine strains. These results will help selecting and improving S. cerevisiae strains for the production of wine and other fermented foods containing DMS such as cheese or beer. • Detection of a new allele with superior preservation of S-methylmethionine (SMM). • High affinity SMM transporter gene MMP1 is the strongest phenotypic contributor. • Single nucleotide polymorphism causing an early STOP codon in MMP1 is decisive. • Variant mostly found in flor yeasts used for the production of characterful wines. • CRISPR/Cas9 mediated base pair exchange in MMP1 resulted in better SMM. [ABSTRACT FROM AUTHOR]

[Display omitted] • Varietal aroma of Vidal blanc in late harvest was different from that in maturation. • Characteristic VOCs and the diversity of microeukaryotes were correlated. • Quantification of stochastic process on shaping microeukaryotic communities. • Important CAZy pathways of epiphytic microbes were identified. • Correlation matrix for high expressed GTs/GHs and active yeasts was established. To study the effects of microeukaryotic communities on development of varietal aroma of Vidal blanc grape during late harvest, metagenomics, gas chromatography–mass spectrometry, climate factors and scanning electron microscopy were jointly used to discover how freeze–thaw stress influences grape skin and shapes the microeukaryotic consortia. Most free terpenes, monoterpenes and C13-norisoprenoids developed during late harvest. Freeze-thaw cycles caused damage of the wax layer and microfissures on the cuticle of grape berries. This increased nutrients availability and supported the dominance of oxidative and fermentative ascomycetous populations. Microbial assemblages possessed certain ecosystem functions, which correlated to the development of characteristic volatile organic compounds, such as free terpenes and phenylalanine derivatives. Significantly upregulated genes of CAZy were identified as FENNEDOB12352, OJNJMGIN252777, EGHMEMAM161340, EGHMEMAM158447, KKFIDJDF144524, BEDCFLNK31943, LHALBBHN88115, BEDCFLNK41042. Zymoseptoria tritici , Kluyveromyces lactis , Yarrowia lipolytica , and Pichia kudriavzevii were selected as key factors in yeast assemblage. [ABSTRACT FROM AUTHOR]

In recent years, many hop varieties with unique aromas, so-called "flavor hops", have been bred and grown. Here, we investigated the effect of late-harvested hops using three flavor hop varieties; Furano Beauty, Furano Magical, and Cascade. The sample hops were harvested at different days after flowering (DAF): DAF 45 (normal harvest), DAF 65, DAF 75, and DAF 85. We measured the volatile thiols in sample cones. The results indicated that 4-methyl-4-sulfanylpentane-2-one contents showed almost no change or a slightly decrease with a delay in harvest, whereas 3-sulfanyl-4-methylpentan-1-ol (3S4MP) content in late-harvested samples increased several fold in comparison with normal-harvested samples. Additionally, 3S4MP contents in the beers brewed with DAF 65 samples were several times higher than those using DAF 45 ones. From these results, we propose a new method to control 3S4MP content in hop cones by changing its harvest date.

• Vineyard calcium sprays shifted wine volatile profile. • Varietal and fermentative metabolites were affected by calcium. • γ-nonalactone was the most susceptible metabolite. • Acetates, alcohols and monoterpenols increased upon calcium treatment. • Calcium reduced volatile phenols, β-damascenone and benzaldehyde. Calcium supplements have increasingly been used at pre-harvest stages for improving fruit firmness, aiming at mitigating environmental stress. However, as recent studies demonstrated that calcium modifies the polyphenolic profile of grape berries, we hypothesize in this study that it also affects wine volatile profile. In a two-year study, grapevines cv. "Vinhão" were sprayed with 2% CaCl 2 throughout the fruiting season, and musts were prepared at a laboratory scale. Musts from calcium-treated fruits contained higher calcium levels and less anthocyanins. Increased calcium content did not affect the course of fermentation induced with a S. cerevisiae starter inoculum, but impacted the course of spontaneous fermentations carried out by endogenous berry microflora. Several compounds associated to varietal and fermentative aromas were largely influenced by the calcium treatment. For instance, volatile phenols decreased, together with β-damascenone, benzaldehyde and γ-nonalactone, while several acetates and alcohols increased. Principal component analysis showed that the volatile profile of control wines produced by spontaneous fermentation substantially differed between replicates, but calcium treatment lowered replicate variability. Volatile profiles were also influenced by the vintage and fermentation type. The shift in wine volatile profile upon calcium treatment may be relevant from an oenological perspective. [ABSTRACT FROM AUTHOR]

Hops are natural ingredients used to impart bitterness and flavor to beer. Recently, new varieties of hops have attracted global research attention. The Sorachi Ace variety, in particular, interests many craft brewers. This hop imparts characteristic varietal aromas, including woody, pine-like, citrus, dill-like, and lemongrass-like, to finished beers. Here, we investigated specific flavor compounds derived from Sorachi Ace using selectable one-dimensional or two-dimensional gas chromatography-olfactometry/mass spectrometry and head space-solid phase microextraction-gas chromatography-mass spectrometry. The results showed that a unique volatile compound, geranic acid, was present at a significant level only in the test beer brewed with the Sorachi Ace hop. Furthermore, sensory evaluation techniques revealed that geranic acid has very unique characteristics. This compound is not odor-active but functions as an enhancer for hop-derived terpenoids at subthreshold levels.