Grape Musts Research Articles

Chemical and Sensory Evaluation of Magnetic Polymers as a Remedial Treatment for Elevated Concentrations of 3-Isobutyl-2-methoxypyrazine in Cabernet Sauvignon Grape Must and Wine.

3-Isobutyl-2-methoxypyrazine (IBMP) is a potent odorant present in grapes and wines that is reminiscent of green capsicum. Suprathreshold concentrations can lead to obvious vegetative characters and suppress desirable fruity aroma nuances in wines, but options to manage IBMP concentrations are limited. This work investigated pre- and postfermentation addition of a putative imprinted magnetic polymer (PIMP) as a remedial treatment for elevated concentrations of IBMP in Cabernet Sauvignon grape must in comparison to nonimprinted magnetic polymer (NIMP) and to a commercially available polylactic acid (PLA) based film added postfermentation. Chemical and sensory analyses of wines showed that PIMP treatments were more effective than PLA film for decreasing "fresh green" aroma nuances without negatively impacting overall aroma profiles and that postfermentation addition of a magnetic polymer removed up to 74% of the initial IBMP concentration compared to 18% for PLA. Prefermentation addition of magnetic polymers removed 20-30% less IBMP compared to that of postfermentation addition but also had less of an effect on other wine volatiles and color parameters.

Effect on White Grape Must of Multiflora Bee Pollen Addition during the Alcoholic Fermentation Process.

The aim of the present study was to compare and analyze the impact of using bee pollen doses (0.1, 0.25, 1, 5, 10 and 20 g/L) as activator in the alcoholic fermentation process of Palomino fino and Riesling wines. In this regard, its influence on the musts composition, the fermentative kinetics, the evolution of the populations of Saccharomyces cerevisiae, the evolution of yeast-assimilable nitrogen and physico-chemical characteristics of final wines has been analyzed. Bee pollen addition produces significant increases in yeast-assimilable nitrogen and maximum yeasts population and exponential velocity reached during alcoholic fermentation. Bee pollen showed an important effect on yeast survival during the death phase. Final wines showed significantly increase in volatile acidity above doses higher than 10 g/L and Comisión Internacional de L’Eclairage parameters (CIELab), color intensity and Abs 420 nm, from 1 g/L. Therefore, pollen could be used as fermentative activator for the alcoholic fermentation of white wines applying doses below of 1 g/L.

Phenolic Compounds in Fruit Beverages

In this current special issue, different aspects related to phenolic compounds in fruit beveragesare presented.[...]

Comparison of two immersion probes coupled with visible/near infrared spectroscopy to assess the must infection at the grape receiving area

The aim of this work was to investigate the applicability of visible/near infrared (vis/NIR) spectroscopy comparing two immersion probes to evaluate the phytosanitary status of must at the grape receiving area to support wineries for an objective quantification of grape infection level.The experimentation was conducted on white and red varieties (Vitis vinifera L.), employing grapes naturally infected with the major wine grape diseases. A total of 159 musts were product and analysed by using a vis/NIR spectrophotometer coupled with two kind of immersion probes: a reflectance probe and a transmittance one. Classification analysis (Partial Least Squares – Discriminant Analysis, PLS-DA) was performed on musts spectra to test the performance of the spectrophotometer, combined with the two probes, to classify healthy and infected samples.Considering three different spectral range analysed (430–1000 nm; 1000–1650 nm; 430–1650 nm), the results obtained from PLS-DA models, in cross-validation, gave values of correctly classified samples (accuracy, %) between 52.5% and 90.4%, and ranged from 68.4% to 84.3% for reflectance and transmittance probes respectively.The optical system was tested in controlled laboratory conditions, simulating the desirable final use of device. A future real scale application could be envisaged inside the analysis tank at the grape receiving area, after setting the operative conditions to perform the measurements directly coupled with the traditional and common quality analysis (soluble solid content and acidity) performed on grape musts sampled at the grape consignment.

Impact of Chemical and Biological Fungicides Applied to Grapevine on Grape Biofilm, Must, and Wine Microbial Diversity.

This study was aimed to measure the impact of the application of a bio-fungicide against Botrytis cinerea on the microbiota involved in the alcoholic fermentation (AF) of Tempranillo Rioja wines. For this purpose, a bio-fungicide composed of the biological control bacterium Bacillus subtilis QST713 was applied to the vineyard. The microbial diversity was analyzed from grape biofilm to wine. Impact on microbial diversity was measured employing indexes assessed with the software PAST 3.10 P.D. Results were compared to non-treated samples and to samples treated with a chemical fungicide mainly composed by fenhexamid. Overall, the impact of the biological-fungicide (bio-fungicide) on the microbial diversity assessed for grape biofilm and for musts was not remarkable. Neither of the tested fungicides enhanced the growth of any species or acted against the development of any microbial groups. The bio-fungicide had no significant impact on the wine microbiota whereas the chemical fungicide caused a reduction of microbial community richness and diversity. Although environmental threats might generate a detriment of the microbial species richness, in this study the tested bio-fungicide did not modify the structure of the microbial community. Indeed, some of the Bacillus applied at the grape surface, were detected at the end of the AF showing its resilience to the harsh environment of the winemaking; in contrast, its impact on wine quality during aging is yet unknown.

Wine yeast phenomics: A standardized fermentation method for assessing quantitative traits of Saccharomyces cerevisiae strains in enological conditions.

This work describes the set up of a small scale fermentation methodology for measuring quantitative traits of hundreds of samples in an enological context. By using standardized screw cap vessels, the alcoholic fermentation kinetics of Saccharomyces cerevisiae strains were measured by following their weight loss over the time. This dispositive was coupled with robotized enzymatic assays for measuring metabolites of enological interest in natural grape juices. Despite the small volume used, kinetic parameters and fermentation end products measured are similar with those observed in larger scale vats. The vessel used also offers the possibility to assay 32 volatiles compounds using a headspace solid-phase micro-extraction coupled to gas chromatography and mass spectrometry. The vessel shaking applied strongly impacted most of the phenotypes investigated due to oxygen transfer occuring in the first hours of the alcoholic fermentation. The impact of grape must and micro-oxygenation was investigated illustrating some relevant genetic x environmental interactions. By phenotyping a wide panel of commercial wine starters in five grape juices, broad phenotypic correlations between kinetics and metabolic end products were evidentiated. Moreover, a multivariate analysis illustrates that some grape musts are more able than others to discriminate commercial strains since some are less robust to environmental changes.

Characterization of an Antioxidant-Enriched Beverage from Grape Musts and Extracts of Winery and Grapevine By-Products

The recovery of antioxidants from complex winery and grapevine by-products into Vitis vinifera must offers new opportunities for wine grapes by the development of a new, enriched fruit juice. However, this demands the search for new valorization methods to get hold of additional antioxidant compounds. The objective of this study was to find a novel functionality for grape pomace, grapevine leaves, and canes by its reuse as a functional matrix for the extraction of antioxidants into grape must. After thermomaceration, 22 polyphenols were identified by high performance liquid chromatography and mass spectrometry. Grape pomace was a good source of anthocyanins (malvidin-3-glucoside), while flavonols (quercetin-3-hexoside) and phenolic acids (caftaric acid) were the main phenolic compounds in leaf extracts. Catechin dimer was the only polyphenol compound present in all of the matrices. Enriched grape juice comprised by 40:20:40 (v/v/v) of pomace, leaf, and cane extracts, yielded an oxygen radical absorbance capacity of pirogallol red and fluorescein ratio of 0.70, indicating that the reactivity of antioxidants present in enriched grape juice was at least as efficient as other polyphenol-rich beverages. Thus, pomace, leaves and canes supply additional polyphenols to grape must that results into a beverage with promissory antioxidant activity and potential health benefits.

Improved detection and enumeration of yeasts in wine by Cells-qPCR

Quantitative PCR by directly sampling (Cells-qPCR) has been adapted to detect and quantify total yeasts, and B. bruxellensis, S. cerevisiae and Z. bailii species, in grape musts and wines. To increase assay sensitivity, the effects of a previous cell wall lysis, by both enzymatic and mechanical methods, were evaluated. Cell wall disruption by mechanical methods showed the best results to enhance assay sensitivity. Numerous standard curves were constructed by mechanically lysed cells in culture medium, and in white and red grape musts and wines. Good regression values (>0.99) and efficiencies (>0.99) were obtained, and it was possible to detect one single cell per reaction in all the matrices. Moreover, the population evolution of yeasts during the winemaking process showed that the method provides an effective tool to detect and enumerate yeasts during industrial wine fermentation, and to rapidly control wine spoilage risks.

CRISPR/Cas9 System as a Valuable Genome Editing Tool for Wine Yeasts with Application to Decrease Urea Production.

An extensive repertoire of molecular tools is available for genetic analysis in laboratory strains of S. cerevisiae. Although this has widely contributed to the interpretation of gene functionality within haploid laboratory isolates, the genetics of metabolism in commercially-relevant polyploid yeast strains is still poorly understood. Genetic engineering in industrial yeasts is undergoing major changes due to Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas) engineering approaches. Here we apply the CRISPR/Cas9 system to two commercial “starter” strains of S. cerevisiae (EC1118, AWRI796), eliminating the CAN1 arginine permease pathway to generate strains with reduced urea production (18.5 and 35.5% for EC1118 and AWRI796, respectively). In a wine-model environment based on two grape musts obtained from Chardonnay and Cabernet Sauvignon cultivars, both S. cerevisiae starter strains and CAN1 mutants completed the must fermentation in 8–12 days. However, recombinant strains carrying the can1 mutation failed to produce urea, suggesting that the genetic modification successfully impaired the arginine metabolism. In conclusion, the reduction of urea production in a wine-model environment confirms that the CRISPR/Cas9 system has been successfully established in S. cerevisiae wine yeasts.

The Impact of Saccharomyces cerevisiae on a Wine Yeast Consortium in Natural and Inoculated Fermentations.

Natural, also referred to as spontaneous wine fermentations, are carried out by the native microbiota of the grape juice, without inoculation of selected, industrially produced yeast or bacterial strains. Such fermentations are commonly initiated by non-Saccharomyces yeast species that numerically dominate the must. Community composition and numerical dominance of species vary significantly between individual musts, but Saccharomyces cerevisiae will in most cases dominate the late stages of the fermentation and complete the process. Nevertheless, non-Saccharomyces species contribute significantly, positively or negatively, to the character and quality of the final product. The contribution is species and strain dependent and will depend on each species or strain’s absolute and relative contribution to total metabolically active biomass, and will therefore, be a function of its relative fitness within the microbial ecosystem. However, the population dynamics of multispecies fermentations are not well understood. Consequently, the oenological potential of the microbiome in any given grape must, can currently not be evaluated or predicted. To better characterize the rules that govern the complex wine microbial ecosystem, a model yeast consortium comprising eight species commonly encountered in South African grape musts and an ARISA based method to monitor their dynamics were developed and validated. The dynamics of these species were evaluated in synthetic must in the presence or absence of S. cerevisiae using direct viable counts and ARISA. The data show that S. cerevisiae specifically suppresses certain species while appearing to favor the persistence of other species. Growth dynamics in Chenin blanc grape must fermentation was monitored only through viable counts. The interactions observed in the synthetic must, were upheld in the natural must fermentations, suggesting the broad applicability of the observed ecosystem dynamics. Importantly, the presence of indigenous yeast populations did not appear to affect the broad interaction patterns between the consortium species. The data show that the wine ecosystem is characterized by both mutually supportive and inhibitory species. The current study presents a first step in the development of a model to predict the oenological potential of any given wine mycobiome.

Biological Demalication and Deacetification of Musts and Wines: Can Wine Yeasts Make the Wine Taste Better?

Grape musts sometimes reveal excess acidity. An excessive amount of organic acids negatively affect wine yeasts and yeast fermentation, and the obtained wines are characterized by an inappropriate balance between sweetness, acidity or sourness, and flavor/aroma components. An appropriate acidity, pleasant to the palate is more difficult to achieve in wines that have high acidity due to an excess of malic acid, because the Saccharomyces species in general, cannot effectively degrade malic acid during alcoholic fermentation. One approach to solving this problem is biological deacidification by lactic acid bacteria or non-Saccharomyces yeasts, like Schizosaccharomyces pombe that show the ability to degrade L-malic acid. Excessive volatile acidity in wine is also a problem in the wine industry. The use of free or immobilized Saccharomyces cells has been studied to solve both these problems since these yeasts are wine yeasts that show a good balance between taste/flavor and aromatic compounds during alcoholic fermentation. The aim of this review is to give some insights into the use of Saccharomyces cerevisiae strains to perform biological demalication (malic acid degradation) and deacetification (reduction of volatile acidity) of wine in an attempt to better understand their biochemistry and enological features.

Membrane Processing of Grape Must for Control of the Alcohol Content in Fermented Beverages

The great demand of beverages, both alcohol-free and with low alcohol content, is a great challenge for the production of beverages with controlled alcohol content through the use of sustainable enological practices. The present work addresses this challenge with the processing of grape must by reverse osmosis (RO) for must reconstitution with different sugar contents prior to the alcoholic fermentation. The original must came from grapes grown in Quinta do Quinto, in Santarem, collected after destemming and mechanic crushing, and preserved in a refrigerated chamber at -1.6 °C until processing by RO. The RO processing was carried out in Escola Superior Agraria de Santarem, with a pilot plant equipped with RO spiral wound modules, M38RO, from Alfa Laval, Denmark. The total membrane permeation area is 15 m2. The work pressure was 55 bar. The original must had 23.7 oBrix, a density of 1108 g.L-1, 15.2% (v/v) of probable alcohol, and a conductivity of 2.01 mS.cm-1. The must reconstitution was carried out, by mixing the concentrated grape must with the vegetal water produced by RO (permeate) to obtain beverages with a nominal alcohol content of 5%, 7%, 10% and 13% (v/v). The fermentation average temperature was between 18.2 and 19.7 °C, and the fnal density rounded about 993 g.cm-3. The beverages were analysed by different parameters, including total polyphenols, total anthocyanins, colour intensity and hue, the coordinates CIELab, alcohol content, total acidity, volatile acidity, pH, free SO2 and total SO2. The attributes of the beverage, corresponding to the visual appearance, aroma and taste senses, as well as the overall judgment were evaluated by the tasters. The proposed method can produce beverages with controlled low alcohol content. The decrease of the alcohol content led to lower content of polyphenols compounds which influenced the sensory evaluatio.

The impact of postharvest dehydration methods on qualitative attributes and chemical composition of ‘Xynisteri’ grape (Vitis vinifera) must

The objective of this study was to compare the effect of traditional sun-drying method (TM) with four alternative dehydration methods [(a) multiple horizontal wires (MHW), (b) multiple vertical pallets (MVP), (c) low greenhouse (LGH) and (d) hot-air dryer treatment (HAD)] on phenolic composition, oenological parameters, aroma potential and browning compounds of musts obtained from dehydrated grapes (Vitis vinifera cv. ‘Xynisteri’). Dehydrated grapes of the examined cultivar are being used to produce ‘Commandaria’ dessert wine, a protected designation of origin product in Cyprus. LGH and HAD treatments led to a significant reduction of the dehydration period. Soluble solid contents were used to monitor the progress of dehydration process; no changes among the examined dehydration methods in reducing sugar composition were found. Notably, HAD led to a dramatic rise (3.2-fold) of titratable acidity that was obviously not related only to the concentration effect. Furthermore, all dehydration methods concentrated total bound volatiles and induced the formation of brown pigments. Based on the Folin-Ciocalteu index, only HAD and LGH induced a significant increase in total phenolic content in dehydrated grape musts. Subsequently, forty phenolic compounds were identified and quantified by LC-DAD-qTOF-MS. Results showed a significant effect of dehydration methods that vary according to the different groups of phenolic compounds considered. Similarly to Folin-Ciocalteu index, HAD and LGH methods increased significantly the phenolic content in grape musts, whereas MHW and MVP methods increased it slightly higher than the concentration factor. Flavonols, flavan-3-ols and flavanonols were the most affected polyphenolic groups. A significant increment of hydroxybenzoic and hydroxycinnamic acids, the predominant groups of phenolic compounds found in ‘Xynisteri’ grapes, was monitored. Taking into consideration that HAD cannot be exploited under the existing legal framework, LGH showed the greatest potential for the production of high quality dehydrated ‘Xynisteri’ grape must.

Cells-qPCR as a direct quantitative PCR method to avoid microbial DNA extractions in grape musts and wines

A novel quantitative PCR assay called Cells-qPCR has been developed for the rapid detection and quantification of yeasts, lactic acid bacteria (LAB) and acetic acid bacteria (AAB) directly from grape must and wine that does not require DNA extraction. The assay was tested on Brettanomyces bruxellensis, Saccharomyces cerevisiae, Lactobacillus plantarum, Oenococcus oeni, Acetobacter aceti and Gluconobacter oxydans in culture media, and in white and red grape musts and wines. Standard curves were constructed from DNA and cells for the six target species in all the matrices. Good efficiencies were obtained for both when comparing DNA and cells standard curves. No reaction inhibition was observed between matrices for each species. Cells quantification was linear over a range of cell concentrations (7, 5 or 4 orders of magnitude) and detected as few as one cell per reaction in all the matrices. The developed Cells-qPCR assay is a robust, reliable, fast and specific method to detect and quantify different yeasts, LAB and AAB species in grape must and wine that avoids DNA extraction and overcomes the presence of inhibitors like polyphenols and ethanol.

Rootstock-scion interaction: 2.effect on the composition of cabernet sauvignon grape must.

ABSTRACT - The interaction between rootstock, scion and the environment may induce different responses to the grapevine physiology and, consequently, to the grape composition. The vineyards of Serra Gaucha, Brazil, are established in different soil types, each with different morphological and physicochemical attributes. Moreover, the grapevines are grafted onto a diversity of rootstocks. Therefore, this study aimed to determine the effect of 15 rootstocks in the composition of the Cabernet Sauvignon (CS) grape must. The following rootstocks were used: Rupestris du Lot, 101-14 Mgt., 3309 C, 420A Mgt., 5BB K, 161-49 C, SO4, Solferino, 1103 P, 99 R, 110 R, Gravesac, Fercal, Dogridge and Isabel, featuring some genetic diversity altogether. The experimental design was in randomized blocks with 15 treatments, three replicates, 10 vines per plot. The grapes were harvested at maturity for four years, and then crushed for winemaking. Next, the grape musts were centrifuged to separate the solid phase from the liquid phase, which was used for analyses related to sugar, acidity and minerals. The data were submitted to correlation analysis and Principal Component Analysis. The main results from the average of four years show that, in general, the grape musts of the CS/101-14 Mgt., CS/161-49 C, CS/3309 C, CS/Rupestris du Lot and CS/Gravesac combinations had high values of density, total soluble solids, pH and °Brix/titratable acidity ratio, and low titratable acidity, which was high with CS/99 R, CS/110 R, CS/Dogridge and CS/1103 P. Potassium had higher concentrations in the grape musts of CS/SO4 and CS/5BB K. Titratable acidity did not correlate with density and total soluble solids, but positively correlated with yield. Density, total soluble solids, and the concentration of potassium were positively correlated with pH. Index terms: Vitis vinifera, grapevine, grafting, composition, minerals.

ROOTSTOCK-SCION INTERACTION: 2. EFFECT ON THE COMPOSITION OF CABERNET SAUVIGNON GRAPE MUST

ABSTRACT The interaction between rootstock, scion and the environment may induce different responses to the grapevine physiology and, consequently, to the grape composition. The vineyards of Serra Gaúcha, Brazil, are established in different soil types, each with different morphological and physicochemical attributes. Moreover, the grapevines are grafted onto a diversity of rootstocks. Therefore, this study aimed to determine the effect of 15 rootstocks in the composition of the Cabernet Sauvignon (CS) grape must. The following rootstocks were used: Rupestris du Lot, 101-14 Mgt., 3309 C, 420A Mgt., 5BB K, 161-49 C, SO4, Solferino, 1103 P, 99 R, 110 R, Gravesac, Fercal, Dogridge and Isabel, featuring some genetic diversity altogether. The experimental design was in randomized blocks with 15 treatments, three replicates, 10 vines per plot. The grapes were harvested at maturity for four years, and then crushed for winemaking. Next, the grape musts were centrifuged to separate the solid phase from the liquid phase, which was used for analyses related to sugar, acidity and minerals. The data were submitted to correlation analysis and Principal Component Analysis. The main results from the average of four years show that, in general, the grape musts of the CS/101-14 Mgt., CS/161-49 C, CS/3309 C, CS/Rupestris du Lot and CS/Gravesac combinations had high values of density, total soluble solids, pH and °Brix/titratable acidity ratio, and low titratable acidity, which was high with CS/99 R, CS/110 R, CS/Dogridge and CS/1103 P. Potassium had higher concentrations in the grape musts of CS/SO4 and CS/5BB K. Titratable acidity did not correlate with density and total soluble solids, but positively correlated with yield. Density, total soluble solids, and the concentration of potassium were positively correlated with pH.

The role of nitrogen uptake on the competition ability of three vineyard Saccharomyces cerevisiae strains

Three vineyard strains of Saccharomyces cerevisiae, P301.4, P304.4 and P254.12, were assayed in comparison with a commercial industrial strain, QA23. The aim was to understand if nitrogen availability could influence strain competition ability during must fermentation. Pairwise-strain fermentations and co-fermentations with the simultaneous presence of the four strains were performed in synthetic musts at two nitrogen levels: control nitrogen condition (CNC) that assured the suitable assimilable nitrogen amount required by the yeast strains to complete the fermentation and low nitrogen condition (LNC) where nitrogen is present at very low level.Results suggested a strong involvement of nitrogen availability, as the frequency in must of the vineyard strains, respect to QA23, in LNC was always higher than that found in CNC. Moreover, in CNC only strain P304.4 reached the same strain frequency as QA23. P304.4 competition ability increased during the fermentation, indicating better performance when nitrogen availability was dropping down. P301.4 was the only strain sensitive to QA23 killer toxin. In CNC, when it was co-inoculated with the industrial strain QA23, P301.4 was never detected. In LNC, P301.4 after 12h accounted for 10% of the total population. This percentage increased after 48h (20%).Single-strain fermentations were also run in both conditions and the nitrogen metabolism further analyzed. Fermentation kinetics, ammonium and amino-acid consumptions and the expression of genes under nitrogen catabolite repression evidenced that vineyard yeasts, and particularly strain P304.4, had higher nitrogen assimilation rate than the commercial control. In conclusion, the high nitrogen assimilation rate seems to be an additional strategy that allowed vineyard yeasts successful competition during the growth in grape musts.

Effect of Grape Syrup as a Replacement for Sugar on the Chemical and Sensory Properties of Sponge Cake

The present study aimed to investigate the possibility of replacing sugar with different concentrations of natural sweetener (grape syrup) in making low-calorie cakes. For this purpose, different types of cakes with 0%, 50%, 75% and 100% grape syrup were cooked. Then, the chemical and sensory properties of cakes such as moisture content and water activity, PH, protein, sugar and fat content as well as acid-insoluble ash, sensory evolution, and color were studied. Results indicated that an increase in the grape syrup content of samples leads to many changes in their chemical and sensory properties. The sample made of 100% grape syrup showed the maximum content of moisture, water activity and high pH value as well as the minimum level of sugar on the seventh day, and the protein content of the sample remained the same as that of the control sample. The results from the comparison of means for the color parameter in seventh day, indicated that the maximum and minimum level of L* (lightness) belonged to the control treatment and the 100% grape syrup treatment, respectively, in which the cake was darker on the seventh day, while the maximum and minimum level of a*(redness) belonged to the 50% grape syrup and control respectively, the maximum (25% grape syrup) and minimum levels of b* (yellowness) belonged to the treatment and control treatment, respectively. The cake with 100% grape syrup obtained the highest score of sensory evaluation in terms of the quality and color of shell as well as soft texture to the cake, taste and aroma.

Exploring the potential of Saccharomyces eubayanus as a parent for new interspecies hybrid strains in winemaking.

Yeast cryotolerance brings some advantages for wine fermentations, including the improved aromatic complexity of white wines. Naturally cold-tolerant strains are generally less adept at wine fermentation but fermentative fitness can potentially be improved through hybridization. Here we studied the potential of using hybrids involving Saccharomyces eubayanus and a S. cerevisiae wine strain for low-temperature winemaking. Through screening the performance in response to variable concentrations of sugar, nitrogen and temperature, we isolated one hybrid strain that exhibited the superior performance. This hybrid strain was propagated and dried in pilot scale and tested for the fermentation of Macabeu and Sauvignon blanc grape musts. We obtained highly viable active dry yeast, which was able to efficiently ferment the grape musts with superior production of aroma active volatiles, in particular, 2-phenylethanol. The genome sequences of the hybrid strains revealed variable chromosome inheritance among hybrids, particularly within the S. cerevisiae subgenome. With the present paper, we expand the knowledge on the potentialities of using S. eubayanus hybrids in industrial fermentation at beverages other than lager beer.

Influence of glycosides on behavior of Oenococcus oeni in wine conditions: growth, substrates and aroma compounds.

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 1mgL-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.