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Geoffrey R Scollary - One of the best experts on this subject based on the ideXlab platform.

  • removal of sulfide bound copper from White Wine by membrane filtration
    Australian Journal of Grape and Wine Research, 2019
    Co-Authors: Nikolaos Kontoudakis, Paul A. Smith, Agnieszka Mierczynskavasilev, Anque Guo, Geoffrey R Scollary, Eric Wilkes, Andrew C Clark
    Abstract:

    Background and Aims Sulfide‐bound copper (Cu) in Wine may act as a potential source of hydrogen sulfide. The aim of this study was to understand how the White Wine matrix can influence the filterability of sulfide‐bound Cu. Methods and Results Sulfide‐bound Cu was formed in situ with addition of copper(II) sulfate and sodium sulfide to White Wine and model Wines. The amount of subsequent Cu passing through membrane filters was measured by flame atomic absorption spectroscopy or inductively coupled plasma with optical emission spectroscopy. Nanoparticle tracking analysis was utilised to measure the size of particles generated after copper(II) and sulfide addition. The majority of the particles were around or below 0.2 μm, and polyethersulfone and nylon membranes remove up to 40–90% of sulfide‐bound Cu from White Wine. The regenerated cellulose, Teflon and glass fibre membranes removed minimal sulfide‐bound Cu. Conclusions Membrane filtration removed sulfide‐bound Cu by adsorption rather than by particle size discrimination. Polysaccharides and proteins were the components of White Wine that most inhibited adsorption. Significance of the Study The addition of copper(II) to Wine with hydrogen sulfide results in products that cannot be removed by filtration on the basis of their particle size but instead may be partly removed by adsorption onto membrane filters to an extent impacted by the Wine composition and the filtration medium.

  • Chemistry of copper in White Wine: a review
    Australian Journal of Grape and Wine Research, 2015
    Co-Authors: Andrew C Clark, Eric Wilkes, Geoffrey R Scollary
    Abstract:

    Copper is one element in Wine that has considerable notoriety. While current Winemaking practice tends to minimise the amount of copper that results from vineyard and Winery sources, the addition of copper(II), either as its sulfate or citrate, to remove sulfidic off-odours may result in an elevated concentration in the finished (bottled) Wine. Residual copper in White Wine has been linked to oxidative and reductive spoilage processes, although the mechanisms are at times speculative. The presence of copper has been implicated in haze formation (copper casse) and linked to protein instability. More recent concerns include the coexistence of residual copper and hydrogen sulfide in Wine stored under low oxygen conditions. The chemistry of copper is important in both White and red Wine. While there are some overlapping issues, especially with respect to sulfidic off-odours, both White and red Wine display their own unique chemistry. Thus, this review describes the state of knowledge of copper in White Wine, differentiating between evidence-based claims and speculation. It also identifies areas of research that will provide a much clearer understanding of the role of copper in Wine spoilage.

  • Copper(II) addition to White Wines containing hydrogen sulfide: residual copper concentration and activity
    Australian Journal of Grape and Wine Research, 2014
    Co-Authors: Andrew C Clark, Paris Grant-preece, N. Cleghorn, Geoffrey R Scollary
    Abstract:

    Background and Aims The long-term effectiveness of copper(II) to remove sulfidic off-odours remains the subject of debate. This study was undertaken to assess the extent of copper removal after its addition to White Wine that contained a variable concentration of hydrogen sulfide and to investigate the activity of the residual copper in a reaction relevant to White Wine ageing. Methods and Results After the addition of sulfide to White Wine, copper(II) was added to give an increasing mole ratio of hydrogen sulfide to copper(II). After settling for 1–5 days, negligible copper was removed after racking or filtering (0.45 or 0.20 μm), as determined by flame atomic absorption spectroscopy. Model Wines were used in an attempt to ascertain the Wine components that may interfere with the removal of the copper sulfide precipitate. Residual copper in the White Wine after racking was active in mediating the production of a phenolic pigment. Conclusions Copper sulfide is not easily removed from White Wine once formed. Model studies confirmed that tartaric acid is a critical factor influencing the extent of copper sulfide precipitation. Significance of the Study This study demonstrates that after addition of copper(II) to Wines containing sulfide, the presence of residual copper is unavoidable and remains active in mediating reactions.

  • chemistry of ascorbic acid and sulfur dioxide as an antioxidant system relevant to White Wine
    Analytica Chimica Acta, 2012
    Co-Authors: Celia Barril, Geoffrey R Scollary, Andrew C Clark
    Abstract:

    The impact of the combined ascorbic acid and sulfur dioxide antioxidants on White Wine oxidation processes was investigated using a range of analytical techniques, including flow injection analysis for free and total sulfur dioxide and two chromatographic methods for ascorbic acid, its oxidative degradation products and phenolic compounds. The combination of different analytical techniques provided a fast and simultaneous means for the monitoring of oxidation processes in a model Wine system. In addition, the initial mole ratio of sulfur dioxide to ascorbic acid was varied and the model Wine complexity was increased by the inclusion of metal ions (copper(II) and iron(II)). Sulfur dioxide was found not to be a significant binder of ascorbic acid oxidative degradation products and could not prevent the formation of certain phenolic pigment precursors. The results provide a detailed insight into the ascorbic acid/sulfur dioxide antioxidant system in Wine conditions.

  • iron iii tartrate as a potential precursor of light induced oxidative degradation of White Wine studies in a model Wine system
    Journal of Agricultural and Food Chemistry, 2011
    Co-Authors: Andrew C Clark, Daniel A Dias, Trevor A Smith, Kenneth P Ghiggino, Geoffrey R Scollary
    Abstract:

    The potential for iron(III) tartrate to act as a photoactivator in light-induced oxidative degradation of White Wine is described. Using a tartaric-acid-based model Wine system containing 5 mg/L iron, exposure to light from a xenon arc lamp led to the oxidative degradation of tartaric acid and the production of glyoxylic acid. The critical wavelength of light for the degradation process was found to be below 520 nm. No glyoxylic acid was formed in the absence of iron and/or light. Flint glass offered little protection from the light-induced photodegradation of tartaric acid. Antique Green glass offered more protection but did not stop the photodegradation process.

Elias Bou-maroun - One of the best experts on this subject based on the ideXlab platform.

  • Molecularly imprinted sol-gel polymers for the analysis of iprodione fungicide in Wine: Synthesis in green solvent
    Food Chemistry, 2019
    Co-Authors: Manal Bitar, Philippe Cayot, Céline Lafarge, Nicolas Sok, Elias Bou-maroun
    Abstract:

    Iprodione is a fungicide widely used in viticulture in most agricultural countries. It was banned recently in the European community because of its carcinogenic and endocrine disrupting characters. In this work, a cheap analytical method able to monitor iprodione in a White Wine was developed. Molecularly imprinted sol-gel polymers (MIS) specific to iprodione and using green solvents were synthesized. An experimental design having the following factors (solvent volume and crosslinker quantity) was used to prepare an optimal MIS. In terms of selectivity, the optimal MIS showed the best partition coefficient towards iprodione in a White Wine containing four other competing fungicides (procymidone, pyrimethanil, azoxystrobin and iprovalicarb). A solid phase extraction method using the optimal MIS was optimized and applied to analyse iprodione in a White Wine. Low detection and quantification limits were reached 11.7 and 39.1 µg/L respectively.

Michael Aviram - One of the best experts on this subject based on the ideXlab platform.

  • White Wine with Red Wine-like Properties: Increased Extraction of Grape Skin Polyphenols Improves the Antioxidant Capacity of the Derived White Wine
    Journal of Agricultural and Food Chemistry, 2001
    Co-Authors: Bianca Fuhrman, Nina Volkova, And Amram Suraski, Michael Aviram
    Abstract:

    Lower antioxidant activity in White Wines in comparison to red Wines lies in the low grape-skin-derived polyphenol content. This paper reports the analysis of the antioxidant capacities of White Wine samples obtained along two different processing procedures directed to enrich the Wine with polyphenols. White Wine samples derived from whole squeezed grapes stored for increasing periods of time (up to 18 h) contained increasing concentrations of polyphenols (from 0.35 to 0.55 mmol/L) and, in parallel, exhibited increased capacity to scavenge free radicals and to inhibit copper ion-induced low-density lipoprotein (LDL) oxidation. However, addition of increasing concentrations of alcohol (up to 18%) to the whole squeezed grapes remarkably augmented the extraction of grape skin polyphenols into the Wine up to 1.25 mmol/L, resulting in an increased capacity of the Wine to scavenge free radicals and to inhibit LDL oxidation, to an extent similar to that of red Wine. The extent of LDL oxidation inhibition was directly related to the Wine polyphenolic content (r = 0.986). It is concluded that processing White Wine by imposing a short period of grape skin contact in the presence of alcohol leads to extraction of grape skin polyphenols and produces polyphenol-rich White Wine with antioxidant characteristics similar to those of red Wine.

  • consumption of red Wine with meals reduces the susceptibility of human plasma and low density lipoprotein to lipid peroxidation
    The American Journal of Clinical Nutrition, 1995
    Co-Authors: Bianca Fuhrman, Alexandra Lavy, Michael Aviram
    Abstract:

    : The effect of consumption of red or White Wine (11% alcohol) with meals on the propensity of plasma and low-density lipoprotein (LDL) to undergo lipid peroxidation was studied in 17 healthy men who were divided into two groups: 8 received 400 mL red Wine/d for 2 wk, and 9 received a similar amount of White Wine. Red Wine consumption for 2 wk resulted in a 20% reduction in the propensity of plasma to undergo lipid peroxidation (in the presence of a free-radical-generating system) as determined by the thiobarbituric acid reactive substances (TBARS) assay. In parallel, red Wine consumption reduced the propensity of the volunteers' LDL to undergo lipid peroxidation (in response to copper ions) as determined by a 46%, 72%, and 54% decrease in the content of TBARS, lipid peroxides, and conjugated dienes in LDL, respectively, as well as by a substantial prolongation of the lag phase required for the initiation of LDL oxidation. On the contrary, dietary consumption of White Wine for 2 wk resulted in a 34% increase in plasma's propensity to undergo lipid peroxidation and also in a 41% increased propensity of the LDL to undergo lipid peroxidation. The antioxidant effect of dietary red Wine on plasma lipid peroxidation was not secondary to changes in the plasma vitamin E or beta-carotene content but could be related to the elevation of polyphenol concentration in plasma and LDL. Thus, some phenolic substances that exist in red Wine, but not in White Wine, are absorbed, bind to plasma LDL, and may be responsible for the antioxidant properties of red Wine.

  • effect of dietary supplementation of red or White Wine on human blood chemistry hematology and coagulation favorable effect of red Wine on plasma high density lipoprotein
    Annals of Nutrition and Metabolism, 1994
    Co-Authors: Alexandra Lavy, Bianca Fuhrman, Arie Markel, Gertrude Dankner, Ami Benamotz, Dita Presser, Michael Aviram
    Abstract:

    Twenty healthy males were divided into two groups: 10 subjects were supplemented for 2 weeks with 400 ml of red Wine (11% alcohol) per day and the other 10 subjects were given 400 ml of White Wine (11

Elizabeth J. Waters - One of the best experts on this subject based on the ideXlab platform.

  • Influence of polysaccharides on the taste and mouthfeel of White Wine
    Australian Journal of Grape and Wine Research, 2016
    Co-Authors: Richard Gawel, Paul A. Smith, Elizabeth J. Waters
    Abstract:

    Background and Aims Mouthfeel attributes of White Wine contribute to its style and therefore to the context in which it is most appropriately consumed. The effect of polysaccharides on the mouthfeel of White Wine and their interaction with pH, ethanol and phenolic substances was determined. Methods and Results White Wine polysaccharides and polysaccharide fractions, defined by molecular mass and composition, were added to either White or model White Wine of variable pH and concentration of alcohol and phenolic substances to assess their effect on White Wine taste and mouthfeel. A higher concentration of polysaccharides reduced perceived palate hotness. The effect of polysaccharides on mouthfeel and taste was independent of the concentration of phenolic substances. A medium molecular mass polysaccharide fraction of 13–93 kDa, containing arabinogalactan protein and mannoprotein reduced palate hotness and increased viscosity at higher pH. Conclusions Polysaccharides had a relatively small effect on mouthfeel and taste compared with the effect of Wine pH and ethanol. Medium molecular mass polysaccharides were mostly responsible for the difference in perceived hotness and viscosity. Significance of the Study Palate hotness is a negative characteristic in White table Wines. Winemaking practices that increase the concentration of arabinogalactan protein and low molecular mass mannoprotein could assist in masking palate hotness in White Wine. Management of pH and alcohol can also be used to significantly influence the taste and mouthfeel in White Wine.

  • White Wine taste and mouthfeel as affected by juice extraction and processing
    Journal of Agricultural and Food Chemistry, 2014
    Co-Authors: Richard Gawel, Steven C. Van Sluyter, Elizabeth J. Waters, Martin P Day, Helen Holt, Paul A. Smith
    Abstract:

    The juice used to make White Wine can be extracted using various physical processes that affect the amount and timing of contact of juice with skins. The influence of juice extraction processes on the mouthfeel and taste of White Wine and their relationship to Wine composition were determined. The amount and type of interaction of juice with skins affected both Wine total phenolic concentration and phenolic composition. Wine pH strongly influenced perceived viscosity, astringency/drying, and acidity. Despite a 5-fold variation in total phenolics among Wines, differences in bitter taste were small. Perceived viscosity was associated with higher phenolics but was not associated with either glycerol or polysaccharide concentration. Bitterness may be reduced by using juice extraction and handling processes that minimize phenolic concentration, but lowering phenolic concentration may also result in Wines of lower perceived viscosity.

  • Effect of pH and Alcohol on Perception of Phenolic Character in White Wine
    American Journal of Enology and Viticulture, 2013
    Co-Authors: Richard Gawel, Steven C. Van Sluyter, Paul A. Smith, Elizabeth J. Waters
    Abstract:

    The in-mouth perception of textures of White Wine arising from the interactions among White Wine phenolics, pH, and alcohol level was evaluated. Phenolics were extracted from White Wines and added back to White Wines that were adjusted to different pH and ethanol concentrations within Wine realistic ranges. Adding phenolics to a White Wine at pH 3.3 significantly increased its astringency, but the same addition did not contribute to the higher astringency elicited by the same Wine when adjusted to pH 3.0. Higher phenolics generally increased bitterness and viscosity, but the effect depended on the source of the phenolics. Wines with added phenolics were generally perceived to be hotter, and significantly so when the Wine was low in alcohol. The combined effect of phenolic content and alcohol concentration on astringency and bitterness was additive, suggesting that alcohol directly contributes to these attributes in White Wines. Overall, the tastes and textures produced by White Wine phenolics were more pronounced in Wines with lower alcohol levels.

  • the effect of glycerol on the perceived viscosity of dry White table Wine
    Journal of Wine Research, 2008
    Co-Authors: Richard Gawel, Elizabeth J. Waters
    Abstract:

    The effect of glycerol on the perceived viscosity of dry White Wines was investigated using direct paired comparison sensory methods. Before tasters assessed Wines for viscosity, the natural sweetness of glycerol needed to first be masked. This was achieved using two novel methods—prior oral exposure to the anti-sweetness agent Gymnema sylvestre, and by sweetness equalisation using a non-viscous high potency artificial sweetener. After masking its sweetness, the addition of 6 g/L of glycerol did not increase the perceived oral viscosity of dry White Wine suggesting that glycerol does not play a role in the perception of dry White Wine viscosity. Therefore, palate viscosity in dry White Wine cannot be enhanced by employing traditional Winemaking approaches that elevate glycerol levels.

  • sulfate a candidate for the missing essential factor that is required for the formation of protein haze in White Wine
    Journal of Agricultural and Food Chemistry, 2007
    Co-Authors: K F Pocock, Geoffrey M Alexander, Yoji Hayasaka, Patrik R Jones, Elizabeth J. Waters
    Abstract:

    Protein haze formation in White Wine is dependent on the presence of both Wine protein and other unknown Wine components, termed factor(s) X. The ability to reconstitute protein haze upon heating artificial model Wine solutions (500 mg/L thaumatin, 12% ethanol, 4 g/L tartaric acid) to which candidate components were added was employed to identify factor(s) X. No protein haze was formed in the absence of additives. The individual or combined addition of caffeic acid, caftaric acid, epicatechin, epigallocatechin-O-gallate, gallic acid, or ferulic acid at typical White Wine concentrations did not generate protein haze. However, PVPP fining of commercial Wines resulted in a reduction in protein haze, suggesting that phenolic compounds may play a modulating role in haze formation. To elucidate the nature of the unknown factor(s) Wine was fractionated and fractions were back-added to model Wine and tested for their essentiality. Wine fractions were generated by ultrafiltration, reverse-phase chromatography, and mixed-mode anion-exchange and reverse-phase chromatography. The only purified fraction containing the essential component(s) was free of phenolic compounds, and analysis by mass spectrometry identified sulfate anion as the dominant component. Reconstitution with KHSO4 using either commercially available thaumatin or Wine proteins confirmed the role of sulfate in Wine protein haze formation. The two main Wine proteins, thaumatin-like protein and chitinase, differed in their haze response in model Wines containing sulfate. Other common Wine anions, acetate, chloride, citrate, phosphate, and tartrate, and Wine cations, Fe(2+/3+) and Cu(+/2+), when added at typical White Wine concentrations were not found to be essential for protein haze formation.

Manal Bitar - One of the best experts on this subject based on the ideXlab platform.

  • Molecularly imprinted sol-gel polymers for the analysis of iprodione fungicide in Wine: Synthesis in green solvent
    Food Chemistry, 2019
    Co-Authors: Manal Bitar, Philippe Cayot, Céline Lafarge, Nicolas Sok, Elias Bou-maroun
    Abstract:

    Iprodione is a fungicide widely used in viticulture in most agricultural countries. It was banned recently in the European community because of its carcinogenic and endocrine disrupting characters. In this work, a cheap analytical method able to monitor iprodione in a White Wine was developed. Molecularly imprinted sol-gel polymers (MIS) specific to iprodione and using green solvents were synthesized. An experimental design having the following factors (solvent volume and crosslinker quantity) was used to prepare an optimal MIS. In terms of selectivity, the optimal MIS showed the best partition coefficient towards iprodione in a White Wine containing four other competing fungicides (procymidone, pyrimethanil, azoxystrobin and iprovalicarb). A solid phase extraction method using the optimal MIS was optimized and applied to analyse iprodione in a White Wine. Low detection and quantification limits were reached 11.7 and 39.1 µg/L respectively.