Fate of yeast and grape pectic polysaccharides of a young red wine in the cross-flow microfiltration process

Cross-flow microfiltration of a young red wine through a mineral membrane of zirconium oxide (average pore size 0.2 μm) laid over a support of agglomerated microporous carbon reduced by 44 % the concentration of the starting wine in soluble polysaccharides. These carbohydrate polymers were mainly constituted of mannose, arabinose, galactose and galacturonic acid associated with minor amounts of rhamnose, glucose, xylose and fucose. The polysaccharides from starting wine and final permeate were separated by gel filtration on Ultrogel AcA 34 (exclusion limit for globular proteins 750,000) in at least four fractions (I-IV) of respective Kav 0.22, 0.50, 0.75 and 0.90. Each polysaccharidic population contained various proportions of yeast mannans, while grape polysaccharides were unequally distributed, fraction I containing neutral type II arabinogalactans and fractions II to IV being complex mixtures of type II arabinogalactans, arabinans and degraded forms of acidic rhamnogalactumnans (pectins). Losses due to microfiltration were positively correlated to hydrodynamic volume (molecular weight) of molecules: (I) "" 79 %, (II) "" 58 %, (III) "" 38 % and (IV) no loss. Yeast and grape polysaccharides coexisting in a given fraction (having the same Kav) were not equally affected by the microfiltration process, yeast mannans passing preferentially the membrane, while grape polymers were more retained. This differential retention was only observed in fractions of high molecular weights (I and II) and was discussed in relation with possible modifications at the molecular level (size and shape of polysaccharides) occurring in the concentration polarisation layer. Application of a back-flush pulse destined to unplug the membrane resulted in a reenrichment of the permeate in the polysaccharides present in the starting wine at a 82 % level

KHT cold stabilization: A scanning electron microscopy study of the formation of surface deposits on stainless steel in model wines

The incidence of yeast cells and wine polysaccharides and polyphenols in the formation of adherent KHT crystals on stainless steel surfaces during cold stabilization was investigated by scanning electron microscopy. Additives were responsible for differences in the deposit configuration, the crystal shape and size as well as in the KHT crystallization kinetics. Yeast cells act as heterogeneous primary nucleation germs for KHT crystal formation. Colloids from wines interacted with KHT crystal faces and affected growth. It was confirmed that polyphenols strongly inhibit the crystallization and result in small crystals with a unidimensional growth. In contrast, with polyphenols, cubic crystals were obtained when wine polysaccharides were associated with yeast cells

Hyperoxidation: influence of various oxygen supply levels on oxidation kinetics of phenolic compounds and wine quality

Chenin blanc, Mauzac and Chardonnay musts were hyperoxidized using three different oxygen levels fixed according to the maximum oxygen consumption capacity determined for each must. Phenolic composition of the control and oxidized musts and that of the corresponding wines were analyzed by HPLC. The wines were also submitted to sensory evaluation. Hyperoxidation hardly modified phenolic composition of Chenin blanc and Mauzac musts which were in fact almost totally oxidized after pressing. As well, it induced no change in wine quality in these two varieties. In Chardonnay musts, concentrations of caffeoyl and p-coumaroyl tartaric acid, 2-S-glutathionyl caffeoyl tartaric acid and catechin decreased with increasing oxygen supplies. Wines contained larger amounts of phenolic compounds than musts because part of the quinones formed during oxidation were reduced when sulfiting, especially for intemediate oxygen levels. Thus, sulfiting should be omitted or delayed to allow quinone condensation and maximum efficency of the hyperoxidation technique. Hyperoxidized Chardonnay wines were rated higher in quality and lower in color than the control

Procyanidin composition of Chardonnay, Mauzac and Grenache blanc grapes

Dimer procyanidins, galloylated or not, and trimers were analysed in three white grape varieties: Chardonnay, Mauzac and Grenache blanc. Procyanidins were extracted from the different components of the grape cluster (seeds, stems, skins and pulps) and then quantified by HPLC. Procyanidin B1 is the major component in stems and skins while procyanidin B2 is the major component in seeds

Dimer and trimer procyanidins in Carignan and Mourvèdre grapes and red wines

Dimer procyanidins, galloylated or not, and trimers were analysed in the red grapes Carignan and Mourvedre. Procyanidins were extracted from the various parts of the grape bunch and then quantified by HPLC. In Carignan and Mourvedre grapes, procyanidin B2 was the major component in seeds, whereas procyanidin B1 was the major component in stems and skins. Trimeric procyanidins were also present in grapes in larger amounts. Various red wines were produced from Carignan and Mourvedre grapes, using different winemaking procedures: entire crushed harvest, destemmed harvest, carbonic maceration and heating of the harvest. Entire crushed harvest gave red wines with the highest levels of procyanidins. An important release of procyanidins, especially procyanidin B1 from skins and stems, when present, occurred.Procyanidines dimères et trimères des raisins et vins rouges de Carignan et MourvèdreDes procyanidines dimères galloylées et non-galloylées, et trimères sont dosées dans deux cépages rouges: Carignan et Mourvèdre. Les procyanidines sont extraites des différentes parties de la grappe puis quantifiées par CLHP en phase inverse. Dans le raisin de Carignan et de Mourvedre, la procyanidine B2 est la plus abondante dans les pepins, tandis que la procyanidine B1 est la plus abondante dans les rafles et pellicules. Les procyanidines trimères sont aussi présentes en quantités importantes. Différents vins rouges ont été élabores à partir des cépages Carignan et Mourvèdre, en utilisant plusieurs téchniques de vinification: vendange foulée; vendange éraflée, macération carbonique et le chauffage de la vendange. Les quantités les plus abondantes de procyanidines sont obtenues dans des vins issus d'une vendange entière et foulée

Environmental Impacts of Tartaric Stabilisation Processes for Wines using Electrodialysis and Cold Treatment

The environmental impacts of the two tartaric stabilisation methods used for wines, electrodialysis andcold treatment, were studied by determining water consumption (for the process and cleaning), wasteproduced (organic load and the composition of wastewater and residues) and energy consumption, atthe pilot stage and in wineries. Thanks to an online treatment of electrodialysis brines by reverse osmosis(industrial facility that treats 30 hL wine/h), the recycling of permeates led to a 65% reduction in waterconsumption, the volume of which represented only 3.9% of the wine treated. When washing and cleaningwater from the ED-RO system was taken into account, overall water consumption was 5.5 L/hL wine. Thepresence of ethanol, due to an osmotic phenomenon with no loss of wine volume, and tartaric acid in thebrines contributes to the organic load of the brine, with a COD of close to 8.4 g O2/L. Overall electricalenergy consumption for stabilisation by electrodialysis (0.21 kWh/hL) turned out to be eight times lowerthan that of cold stabilisation. An evaluation of cold stabilisation effluents revealed that 66.6% of the CODdischarged came from the diatomaceous earth (DE), 21.8% from the washing of the filter and 11.4% fromthe washing of the cold treatment tank. The production of used DE was 2.64 g (wet weight)/L of wine, andthe ethanol present in the DE waste represented a loss in wine volume of 0.14 L/hL

Phenolic and furanic compounds of Portuguese chestnut and French, American and Portuguese oak wood chips

Botanical species used on aging process must be wisely and judiciously chosen, and for this selection, a basic knowledge of the chemical composition of woods is warranted. Aiming to contribute to extend the knowledge of the chemical composition of several wood species useful for enological purposes, we have focused our studies on Portuguese chestnut and French, American and Portuguese oak chips. The profile of low molecular weight phenolic composition of these chips was achieved, using an optimized extraction method based on pressurized liquid extraction, followed by the quantification of phenolic acids, phenolic aldehydes and furanic derivatives by high-performance liquid chromatography (HPLC-DAD). The identification of those compounds was also confirmed by LC-DAD/ESI-MS. This study allowed the determination of the low molecular phenolic composition of Portuguese chestnut and French, American and Portuguese oak wood. According to our results, the influence of the botanical species seems to be more relevant than the geographic origin of the wood species

Colour products of reaction between malvidin 3-glucoside, flavanols and acetaldehyde

The anthocyanins are present in the grapes as monomers, but aged red wines have only linked anthocyanins in the different polymers. One of the possible reaction of red wine colourant is the forming of linkage between the anthocyanins and flavanols by (CH2CH) bridge of acetaldehyde. The formation of coloured products between malvidin 3-glucoside, acetaldehyde and (-)epicatechin, its dimer B2 and oligomers was analysed by liquid chromatography (HPLC). These polymeric compounds were hydrolyzed in the presence of toluen-α-thiol (thiolysis) for the determination the linkage place of anthocyanins with flavanols. The model studies showed, that the procyanidins were linked by "top molecule" across of aldehyde bridge with malvidine, because the coloured toluen-α-thiol derivatives were obtained. The spectrum of these compounds had the maximum at 240 nm corresponding to toluen-α-thiol molecule and other maximum in visible region had shift to longer wavelength. This is characteristic for the polymers of anthocyanins with flavanols. In the red wine after thiolysis, the compounds were identified by the HPLC method with the same retention time as in the model solution, but only in the presence of acetyladehyde being previously added.Metodą chromatografii cieczowej wysokosprawnej badano proces tworzenia się kompleksów antocyjanów, flawanoli z aldehydem octowym w roztworach modelowych i czerwonym winie. Kompleksy te są jednymi z możliwych barwnych substancji czerwonych dojrzałych win. Produkty kondensacji pomiędzy malwidyno 3-glukozydem, aldehydem octowym, (-)epikatechiną oraz jej dimerem B2 i oligomerami poddano hydrolizie w obecności tolueno-α-tiolu, aby określić miejsca powstawania wiązań w tych kompleksach z procy- janidynami. Doświadczenia wykazały, że procyjanidyny łączą się swą górną cząsteczką poprzez mostek aldehydowy z malwidyną. Uzyskano drogą tiolizy barwne pochodne tiolowe (Rysunek 2). Widmo tych związków posiada maksimum przy 240 nm odpowiadające cząsteczce tolueno-alfa-tiolu oraz ma przesunięte maksimum w zakresie światła widzialnego w kierunku fal dłuższych (Rysunek 3). Jest to charakterystyczne dla kompleksów antocyjanów z flawanolami. W czerwonym winie po tiolizie stwierdzono obecność podobnych związków jak w roztworze modelowym, ale tylko po uprzednim dodaniu aldehydu octowego (Rysunek 5)

Etude de l'évolution des propriétés de transport des membranes d'électrodialyse lors de leur encrassement par des polyphénols de moûts de raisins

Lors de toute électrodialyse de solutions de substances naturelles les performances des membranes semi-perméables aux ions varient par suite de l'encrassement.L'évolution au cours du temps des propriétés de transport des membranes d'un électrodialyseur a été étudiée avec quatre méthodes dans le cas où les modifications sont provoquées en déminéralisant des moûts très colorés de raisin.Les trois premières méthodes ne nécessitent pas de démonter le module d'électrodialyse et concernent le couple de membranes semi-perméables aux anions et aux cations. a