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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]

Cold maceration (CM) is widely applied in winemaking to improve wine aroma and overall quality. However, more efficient CM techniques for industrial-scale winemaking are still needed. This study examined the impact of CM with indigenous cryotolerant Metschnikowia pulcherrima Mp0520 (Mp-CM) on the Muscat wine aromatic characteristics. The results demonstrated a significant divergence in the types and concentrations of aroma compounds between Mp-CM wine and the control. The Mp-CM wine exhibited a significantly higher terpenes content, resulting in a Muscat wine characterized by terpenes, compared to the control predominated by esters. Additionally, the Mp-CM wine demonstrated elevated levels of α-terpineol and terpinolene, potentially enhancing the varietal aroma stability of Muscat wine. Furthermore, Mp-CM gave Muscat wine a heightened fruity aroma and a more complex aroma. These findings suggested that the Mp-CM utilized in this study offered promising avenues for enhancing the variety aroma characteristics of Muscat wine on large scale winemaking. • Mp0520 effects the fungal microbial community in cold maceration broth. • Mp0520 shows great increase in cell wall hydrolase activities in the maceration broth. • Mp0520 increases the content of terpenes in wine. • Mp0520 highlights wine varietal characteristics and improves wine aroma quality. • Mp0520 shows wide application potential in winemaking. [ABSTRACT FROM AUTHOR]

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]

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]

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]

Abstract: In this work, the harvest variability of the varietal composition of Fernão-Pires grape variety was evaluated using a dichloromethane liquid–liquid continuous extraction followed by GC-qMS of the free (F) and potential varietal components (PVC) from the musts across four harvests (1998, 1999, 2000, and 2002). This study showed that Fernão-Pires musts exhibited varietal volatile composition variability along the years. Based on the data obtained, using GC-qMS in tandem with PCA, relationships were established between the varietal volatile composition of the musts and the white wine aroma quality classification conferred by the official wine taster chamber. The results of the volatile analyses were consistent with the wine quality classification, indicating that the wine aroma quality is clearly associated with the musts free varietal volatile composition. On the other hand, the PVC fraction allowed the distinction of the musts according to the composition of potential aroma precursors. The proposed approach can provide information to winemakers concerning the winemaking methodologies that can be implemented to improve the varietal wine aroma quality. [ABSTRACT FROM AUTHOR]

Semi-synthetic must containing standard nutrients, a phenolic and aromatic fraction extracted from Albariño grapes and synthetic precursors of 3-mercaptohexanol (MOH) and 4-mercapto-4-pentan-2-one (MMP) were fermented with three different selected commercial S. cerevisiae yeasts. Wines were subjected to anoxic aging at 50 °C for 1, 2, 5 and 8 weeks, and their volatile composition was comprehensively determined by the analysis of 86 different aroma compounds using five different GC methods. Yeasts exert a strong influence on wine aroma throughout the whole aging period. Their effects extend beyond the well-known actions on yeast secondary metabolites, including the formation of little amounts of Strecker aldehydes or the formation of acids precursors of fruity esters, and on the enzymatic actions on the different grape aroma precursors. Additionally, yeasts influence wine aroma; first, by producing SO 2 which reacts with β-damascenone and increases Strecker aldehyde production in fermentation; second, by inducing the differential accumulation of Strecker aldehydes during anoxic aging; and third, by determining the stability of MOH, likely because of its reaction with vinylphenols or other yeast-related electrophiles. [Display omitted] • Yeast strain significantly affected wine aroma throughout aging. • Yeast-related little amounts of Strecker aldehydes found after fermentation. • Relevant increases with aging in three Strecker aldehydes in anoxic conditions. • Yeast-related differences in the stability of MOH during anoxic aging. • Relevant roles for yeast-related amino acids, dicarbonyls, SO 2 and vinylphenols. [ABSTRACT FROM AUTHOR]

Abstract: Twenty-three monovarietal wines from 13 white and red grapes have been analysed by solid phase extraction–gas chromatography and solid phase micro-extraction–gas chromatography. The content of some varietal terpenic and fermentative volatile compounds was determined. The 13 studied varieties were characterised as well as the influence of winemaking practices like cold soaking and addition of glycosidase enzymes. Terpenic compounds showed a high variability between the 13 varieties which allows for its characterisation. The winemaking practices devoted to increase the aromatic properties of wines produced different results depending on the variety of grape. For example, cold soaking produced very different results if applied on Palomino fino variety or on Traminer variety, whereas for Viura variety few changes were found. Regarding the volatile compounds generated during the alcoholic fermentation, its relative amount is clearly related to the kind of fermentation process carried out, and particularly according to whether maceration of the solid parts has or has not been done during the process. In the case of vinification without maceration, there is a relative increase of fatty acids and their ethyl esters, whereas in vinification with maceration, the ethyl esters of lactic, acetic and succinic acids are the compounds that are relatively more abundant. Additionally, none of these compounds was affected by the techniques applied to increase varietal aroma, i.e. cold soaking, and addition of glycosidase enzymes showed very low influence in the levels of this kind of compounds. [Copyright &y& Elsevier]

Varietal compounds have been analyzed in wines prepared in the laboratory from four grape varieties grown in Spain. The possibilities for enhancing their aroma afforded by addition of glycosidase enzymes and steeping with the skin were studied. Both treatments increased substances responsible for varietal aroma in all wines, the effect being particularly significant for benzyl alcohol. [Copyright &y& Elsevier]

• 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]