IMPACT DES ENZYMES DE MACERATION SUR LA COMPOSITION EN POLYSACCHARIDES ET EN POLYPHENOLS DES VINS ROUGES – ETUDE DE L'EVOLUTION DE CES COMPOSES EN SOLUTION MODELE VIN.

Conversion of grape berries in wine is a complex process. Technological auxiliaries such as enzymes have been developed to improve wine quality. This quality depends on the phenolic composition: anthocyanins are responsible for wine colour and tannins for astringency. Macerating enzymes, that degrade grape berry cell walls, are used to improve yield of free run juice and increase extraction of pigments and tannins. However, these treatments remain empirical and conflicting results have been obtained on their effect on the release of pectic polysaccharides from the cell walls and on the phenolic composition of wines. The aim of this work was to study the effect of macerating enzymes on the polysaccharide and polyphenol composition of red wines. An increase of tannins and RG-II and a decrease of polysaccharides rich in arabinose and galactose have been observed in enzyme-treated wines. These wines have a higher colour intensity than the controls, which can be explained by an increase of pigments formed by reactions of anthocyanins with tannins. Effects were more or less pronounced depending on the vintage. For the first time, wine oligosaccharides have been isolated and characterized. They arise from the degradation of pectin smooth regions in the control wines and from pectin hairy regions in enzyme-treated wines. As enzymes modify wine polysaccharide and polyphenol composition, the evolution of these compounds have been studied in wine model solution so as to understand their reactivity and their impact on colour and on wine stability.La transformation du raisin en vin est un procédé complexe. Des auxiliaires technologiques comme les enzymes ont été développés pour faciliter ce procédé et améliorer la qualité des vins. Cette qualité est influencée par les composés phénoliques : les anthocyanes sont responsables de la couleur rouge et les tanins de la sensation d'astringence. Les enzymes de macération qui dégradent les parois cellulaires du raisin sont utilisées pour améliorer les rendements en jus et l'extraction des pigments et des tanins. Cependant, ces traitements sont utilisés de manière empirique et leur impact sur la libération des polysaccharides pectiques constitutifs des parois et la composition en composés phénoliques des vins reste controversée. Dans cette étude, un enrichissement des vins enzymés en tanins et en RG-II et une diminution des polysaccharides riches en arabinose et en galactose libérés par la dégradation des parois ont été démontrés. Les vins enzymés présentent une intensité colorante plus élevée que les vins témoins expliquée par une augmentation des pigments issus des réactions entre anthocyanes et tanins. Les effets sont plus ou moins marqués suivant le millésime. Pour la première fois, les oligosaccharides des vins ont été isolés et caractérisés. Les structures des oligosaccharides présentes dans les vins témoins résultent de la dégradation des zones lisses des pectines, les vins enzymés renferment des composés provenant des zones hérissées des pectines. Pour comprendre l'impact des modifications induites par les enzymes sur la qualité et plus particulièrement la couleur et la stabilité des vins, l'évolution des polysaccharides et des polyphénols a été suivie en milieu modèle

Impact des enzymes de macération sur la composition en polysaccharides et en polyphénols des vins rouges (Etude en solutions modèle vin de l'évolution de ces composés)

La transformation du raisin en vin est un procédé complexe. Des auxiliaires technologiques comme les enzymes ont été développés pour améliorer la qualité des vins. Cette qualité est influencée par les composés phénoliques : les anthocyanes sont responsables de la couleur rouge et les tanins de la sensation d'astringence. Les enzymes de macération qui dégradent les parois cellulaires du raisin sont utilisées pour améliorer les rendements en jus et l'extraction des pigments et des tanins. Cependant, ces traitements sont utilisés de manière empirique et leur impact sur la libération des polysaccharides pectiques constitutifs des parois et la composition en composés phénoliques des vins reste controversée. Dans cette étude, un enrichissement des vins enzymés en tanins et en RG-II et une diminution des polysaccharides riches en arabinose et en galactose libérés par la dégradation des parois ont été démontrés. Les vins enzymés présentent une intensité colorante plus élevée que les vins témoins expliquée par une augmentation des pigments issus des réactions entre anthocyanes et tanins. Les effets sont plus ou moins marqués suivant le millésime. Pour la première fois, les oligosaccharides des vins ont été isolés et caractérisés. Les structures des oligosaccharides présents dans les vins témoins résultent de la dégradation des zones lisses des pectines, les vins enzymés renferment des composés provenant des zones hérissées des pectines. Pour comprendre l'impact des modifications induites par les enzymes sur la qualité et plus particulièrement la couleur et la stabilité des vins, l'évolution des polysaccharides et des polyphénols a été suivie en milieu modèleConversion of grape berries in wine is a complex process. Technological auxiliaries such as enzymes have been developed to improve wine quality. This quality depends on the phenolic composition: anthocyanins are responsible for wine colour and tannins for astringency. Macerating enzymes, that degrade grape berry cell walls, are used to improve yield of free run juice and increase extraction of pigments and tannins. However, these treatments remain empirical and conflicting results have been obtained on their effect on the release of pectic polysaccharides from the cell walls and on the phenolic composition of wines. The aim of this work was to study the effect of macerating enzymes on the polysaccharide and polyphenol composition of red wines. An increase of tannins and RG-II and a decrease of polysaccharides rich in arabinose and galactose have been observed in enzyme-treated wines. These wines have a higher colour intensity than the controls, which can be explained by an increase of pigments formed by reactions of anthocyanins with tannins. Effects were more or less pronounced depending on the vintage. For the first time, wine oligosaccharides have been isolated and characterized. They arise from the degradation of pectin smooth regions in the control wines and from pectin hairy regions in enzyme-treated wines. As enzymes modify wine polysaccharide and polyphenol composition, the evolution of these compounds have been studied in wine model solution so as to understand their reactivity and their impact on colour and on wine stabilityMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Evolution of flavanol glycosides during red grape fermentation

Monomeric and dimeric flavanol glycosides were quantified by UHPLC-MRM in Syrah (SYR) and Grenache (GRE) grapes and in their corresponding wines for the first time. Quantities were extremely variable depending on grape tissue (seeds or skins) and during fermentation. Overall, 22 monomeric and dimeric mono- and diglycosides were determined with concentrations ranging from 0.7 nanograms to 0.700 micrograms per gram of grape tissue, and 0 to 60 micrograms per liter for wines. The evolution of the glycosides' composition during winemaking suggests that almost all these compounds originate in the grapes themselves and display different extraction kinetics during winemaking. One isomer of the monomeric (epi) flavanol monoglycosides seemed to be biosynthesized by yeasts during wine fermentation. The sharp decrease in concentration of some isomers at the late stages of fermentation or after pressing suggests that some grape glycosidase activities convert these compounds into non-glycosylated flavanols

Effect of Macerating Enzymes on the Oligosaccharide Profiles of Merlot Red Wines

International audienceCommercial pectinase preparations are applied in winemaking to improve wine processing and final quality. These preparations contain pectolytic enzyme activities such as polygalacturonases, pectin esterases, pectin lyases, and rhamnoglacturonases. These enzymes modify the polysaccharide and oligosaccharide composition of wines. The influence of various commercial enzyme preparations on wine oligosaccharide composition was studied, on Merlot wines from the Bordeaux area. Wine oligosaccharides were isolated by high-resolution size-exclusion chromatography on a Superdex-30 HR column. The glycosyl residue and glycosyl linkage compositions of the oligosaccharide fractions obtained were determined. The MS spectra of the Merlot oligosaccharide fractions from control and enzyme-treated wines were recorded on an AccuTOF mass spectrometer equipped with an electrospray ionization (ESI) source and a time-of-flight (TOF) mass analyzer. Oligosaccharides in the control wines were partly methylated homogalacturonans, corresponding to smooth regions of pectins, whereas those of the enzyme-treated wines were mostly rhamnogalacturonan-like structures linked with neutral lateral chains, arising from the hairy regions. The enzyme preparations used thus cleaved the rhamnogalacturonan backbone of the hairy zones and demethylated and hydrolyzed the smooth regions. Besides, different structures were detected, depending on the enzyme preparation used, indicating that they contained rhamnogalacturonase activities with different specificities. The oligosaccharide profiles can serve as a marker of enzymatic treatments

Assessing a new crusher aimed at delivering wines with improved polyphenols and flavours

Assessing a new crusher aimed at delivering wines with improved polyphenols and flavour

The dynamic crusher: a new technological concept for extraction in harvested grapes in enology

The dynamic crusher: a new technological concept for extraction in harvested grapes in enology. 15. Australian Wine International Technical Conference (AWITC

Assessing a new crusher aimed at delivering wines with improved polyphenols and flavours

Assessing a new crusher aimed at delivering wines with improved polyphenols and flavour

Unraveling the color of Rosé wines

conférence plénièreUnraveling the color of Rosé wines. 7. International Workshop on Anthocyanins - IWA 201

Unravelling the color of a worldwide Rosé wine collection by UHPLC-MRM-MS polyphenol profiling

Unravelling the color of a worldwide Rosé wine collection by UHPLC-MRM-MS polyphenol profiling. 64. ASMS conference on Mass Spectrometry and Allied Topic

Méthodes rapides d'estimation de l'astringence des vins rouges

Méthodes rapides d'estimation de l'astringence des vins rouges. 7. Journées scientifiques de la vigne et du vi