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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.

Background and Aims: Musts with a high concentration of gluconic acid can be obtained because of the colonization of grapes by spoilage fungi and bacteria or the treatment of musts with glucose oxidase. Our research aims to obtain yeast strains capable of degrading this gluconic acid. Methods and Results: Assays were conducted by inoculating selected strains of Schizosaccharomyces pombe in both must and wine. The most effective strategy to achieve the highest gluconic acid consumption was the inoculation of S. pombe strains into the must. Fermentations of Verdejo grape must, supplemented with sodium gluconate, were conducted using strains of S. pombe in both unique and sequential inoculations with a strain of Saccharomyces cerevisiae at 24 and 48 h. A metabolic and kinetic variability were observed in the consumption of glucose, fructose, malic acid, and gluconic acid among the strains under investigation that exhibited a high fermentation power and capacity to degrade up to 100% of malic acid. Conclusions: The S. pombe strains, Sp3 and Sp7, consumed the highest amount of gluconic acid, 90.5 ± 3.7% and 63.9 ± 3.6%, respectively. Sequential inoculations at 24 h significantly reduced gluconic acid consumptions. In contrast, sequential inoculations at 48 h demonstrated no differences with the unique Strains Sp1, Sp3, and Sp4.

Higher temperatures due to climate change are causing greater sugar production in grapes and more alcoholic wines. The use of glucose oxidase (GOX) and catalase (CAT) in grape must is a biotechnological green strategy to produce reduced-alcohol wines. GOX and CAT were effectively co-immobilized by sol-gel entrapment in silica-calcium-alginate hydrogel capsules. The optimal co-immobilization conditions were achieved at a concentration of the colloidal silica, sodium silicate and sodium alginate of 7.38%, 0.49% and 1.51%, respectively, at pH 6.57. The formation of a porous silica-calcium-alginate structure was confirmed by environmental scanning electron microscopy and the elemental analysis of the hydrogel by X-ray spectroscopy. The immobilized GOX showed a Michaelis–Menten kinetic, while the immobilized CAT fits better to an allosteric model. Immobilization also conferred superior GOX activity at low pH and temperature. The capsules showed a good operational stability, as they could be reused for at least 8 cycles. A substantial reduction of 26.3 g/L of glucose was achieved with encapsulated enzymes, which corresponds to a decrease in potential alcoholic strength of must of about 1.5% vol. These results show that co-immobilized GOX and CAT in silica-calcium-alginate hydrogels is a promising strategy to produce reduced-alcohol wines.

α‐Synuclein is a synaptic modulatory protein implicated in the pathogenesis of Parkinson disease. The precise functions of this small cytosolic protein are still under investigation. α‐Synuclein has been proposed to regulate soluble N ‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) proteins involved in vesicle fusion. Interestingly, α‐synuclein fails to interact with SNARE proteins in conventional protein‐binding assays, thus suggesting an indirect mode of action. As the structural and functional properties of both α‐synuclein and the SNARE proteins can be modified by arachidonic acid, a common lipid regulator, we analysed this possible tripartite link in detail. Here, we show that the ability of arachidonic acid to stimulate SNARE complex formation and exocytosis can be controlled by α‐synuclein, both in vitro and in vivo . α‐Synuclein sequesters arachidonic acid and thereby blocks the activation of SNAREs. Our data provide mechanistic insights into the action of α‐synuclein in the modulation of neurotransmission. The fatty acid‐binding protein alpha‐synuclein has been proposed to regulate SNARE proteins. This report shows that alpha‐synuclein sequesters fatty acids to down‐regulate SNARE assembly thereby inhibiting exocytosis.

Glucose oxidase (GOX) and catalase (CAT) were co-immobilized in silica–calcium–alginate hydrogels to degrade must glucose. The effect of the enzyme dose (1.2–2.4 U/mL), the initial must pH (3.6–4.0), and the incubation temperature (10–20 °C) on the glucose consumption, gluconic acid concentration, pH, and color intensity of Verdejo must was studied by using a Box–Behnken experimental design and comparing free and co-immobilized enzymes. A reduction of up to 37.3 g/L of glucose was observed in co-immobilized enzyme-treated must, corresponding to a decrease in its potential alcohol strength of 2.0% vol. (v/v), while achieving a slight decrease in its pH (between 0.28 and 0.60). This slight acidification was due to a significant reduction in the estimated gluconic acid found in the must (up to 73.7%), likely due to its accumulation inside the capsules. Regarding the operational stability of immobilized enzymes, a gradual reduction in glucose consumption was observed over eight consecutive cycles. Finally, co-immobilized enzymes showed enhanced efficiency over a reaction period of 48 h, with an 87.1% higher ratio of glucose consumed per enzyme dose in the second 24 h period compared with free enzymes. These findings provide valuable insights into the performance of GOX–CAT co-immobilized to produce reduced-alcohol wines, mitigating excessive must acidification.

Ageing on lees can be a good technique to enhance the quality of red sparkling base wines. Ultrasound treatment of the lees, prior to addition to the wine, can improve the releasing of their components into the wine. This study carries out a four month ageing on lees of a red sparkling base wine by the addition of lees sonicated at different amplitude levels: 30%, 60% and 90% for 10 min. The ageing on ultrasound-treated lees improved the quality of the red base wine, with a greater impact the higher the amplitude of the applied ultrasound. Sonicated lees at an amplitude of 90% enlarged the concentration of neutral polysaccharides in the wine and reduced its astringency, which was evaluated chemically. Furthermore, this treatment enhanced the concentration of some volatile compounds in the wine, mainly acetates, esters and terpenes with floral and fruity aromatic notes. This trend was also found for some fused alcohols, contributing to the aromatic complexity of wines, as well as for 2-phenylethanol, an alcohol with a rose-like aroma, and also for C6-alcohols with a green-herbaceous aroma. The results indicate that ultrasonication is a promising tool to increase the benefits of ageing on lees on the quality of red sparkling base wines.

Currently, non-Saccharomyces yeasts are the subject of interest, among other things, for their contribution to the aromatic complexity of wines. In this study, the characterisation of non-Saccharomyces yeasts was addressed by their isolation during spontaneous fermentations of organic Verdejo grapes, obtaining a total of 484 isolates, of which 11% were identified by molecular techniques as non-Saccharomyces yeasts. Fermentative isolates belonging to the species Hanseniaspora meyeri, Hanseniaspora osmophila, Pichia guilliermondii, Pichia kudriavzevii, Torulaspora delbrueckii, and Wickerhamomyces anomalus were analysed. Significant differences were found in the yeast populations established at the different fermentation stages. Interestingly, W. anomalus stood up as a widely distributed species in vineyards, vintages, and fermentation stages. Several of the strains studied stood out for their biotechnological potential in the production of Verdejo wine, showing the presence of relevant enzymatic activity for the release of varietal aromas and the technological improvement of the winemaking process. Three enzymatic activities were found in an important number of isolates, β-glucosidase, protease, and β-lyase, implicated in the positive aromatic impact on this style of white wine. In that sense, all the isolates of W. anomalus presented those activities. T. delbrueckii isolates were highlighted for their significant β-lyase activity. In addition, T. delbrueckii was outlined because of its potential to achieve an elevated fermenting power, as well as the lack of lag phase. The results obtained highlight the importance of maintaining the microbial diversity that contributes to the production of wines with unique and distinctive characteristics of the production region.

Two strains of Saccharomyces cerevisiae (Sc01 and Sc02) and one strain of Wickerhamomyces anomalus (Wa) were isolated from organic Verdejo spontaneous fermentations and used for the development of experimental winemaking. Sc01 and Sc02 represented 52.7% of the population of the Saccharomyces strains isolated throughout the fermentation process. W. anomalus appeared as the predominant species among the non-Saccharomyces yeasts. Wa turned out to be the strain of this species with the shortest lag phase and positive enzymatic activities, and it was selected for white wine production. Fermentations with unique inoculation of S. cerevisiae strains were compared with sequential inoculation with W. anomalus. The results showed that the sequential inoculations did not affect the fermentation kinetics or physicochemical characteristics of the wines compared with the unique inoculations. However, this study identified a significant impact on the aromatic profiles of the produced wines due to the sequential inoculations. This modification resulted in a similar new aromatic profile in both sequential inoculations, demonstrating common characteristics related to the contribution of W. anomalus. In general, the sequential fermentations were mainly characterized by lower levels of acetate esters and an increase in ethyl acetate levels, whereas lower levels of ethyl octanoate and ethyl dec-9-enoate were detected. Propan-1-ol and butan-1-ol showed an increase in the sequential fermentations, while 4-methylpentan-1-ol and 2-phenylethanol were found in lower concentrations. These results highlight the great influence that the presence of specific strains of native non-Saccharomyces yeasts exerts on the characteristics of elaborate wines.

This study focuses on improving the second fermentation and the in-bottle ageing over lees process for 9 and 21 months of a red sparkling wine. The aim of the study was to enhance wine quality and try to make it more pleasant for consumers. For this purpose, four different yeast derivatives (yeast walls, yeast walls with tannins, inactivated yeasts and mannoproteins) and β-glucanases were added to a red base sparkling wine and were aged over lees during two different periods: 9 and 21 months. Oenological parameters, total polysaccharides, total proteins, free amino nitrogen, phenolic composition, foaming properties, and volatile compounds were analysed in conjunction with a sensory evaluation. Results show the different incidences of the studied adjuvants on the final parameters, highlighting the importance of the interactions of the studied adjuvants over time. In fact, time itself turned out to be one of the main factors affecting the final characteristics of the wine, so influencing consumers’ opinions and modifying the wine’s acceptability and quality.

Microbial populations in spontaneous winemaking contribute to the distinctiveness and quality of the wines. In this study, molecular methods were applied to 484 isolated yeasts to survey the diversity of the Saccharomyces cerevisiae population in spontaneous fermentations of organic Verdejo grapes. Identification was carried out at strain level for samples from different vineyards correct.and stages of the winemaking process over the course of two vintages, establishing 54 different strains. The number of isolates belonging to each strain was not homogeneous, as two predominant strains represented more than half of the isolates independent of vineyard or vintage. Regarding the richness and abundance, differences among the stages of fermentation were confirmed, finding the highest diversity values in racked must and in the end of fermentation stages. Dissimilarity in S. cerevisiae communities was found among vineyards and vintages, distinguishing representative groups of isolates for each of the populations analysed. These results highlight the effect of vineyard and vintage on yeast communities as well as the presence of singular strains in populations of yeasts. Oenologically relevant enzymatic activities, β-lyase, protease and β-glucanase, were detected in 83.9%, 96.8% and 38.7% of the isolates, respectively, which may be of interest for potential future studies.