Influence of wine polysaccharides and polyphenols on the crystallization of potassium hydrogen tartrate

Abstract

<p style="text-align: justify;">Potassium hydrogen tartrate (KHT) is a natural compound of wine which crystallizes spontaneously. Whereas crystal occurrence can be considered as a sign of goodness in old and famous vintage wines, it is usually thought of as a serious failure for most consumers, even though it does not alter wine quality. An efficient and cheap process of wine stabilization versus KHT crystallization has to be found yet. An alternate process to physical stabilization of wines may lie in the addition of an inhibitor of KHT crystallization. Bearing this in mind, we have investigated the effect of several polysaccharides and total polyphenols fractions on KHT crystallization through the measurement of crystal appearance time (induction time) with and without any macromolecule.</p><p style="text-align: justify;">Red wines. white wines and KHT supersaturated hydroalcoholic solution exhibit different behaviours versus KHT crystallization, red wines crystallizing less easily than white wines and far less easily th an hydroalcoholic solution. Those differences can be explained by our results. The innate inhibition of red wines is the sum of the inhibiting effects of rhamnogalacturonans (RG-I and RG-II), yeasts mannoproteins present in wine and of total polyphenols. Arabinogalactans show no effect on KHT crystallization whereas rhamnogalacturonans display a peculiar concentration dependent behaviour : crystal appearance is accelerated at low concentration and slowed at high concentration. More strongly observed for RG-1I2 fractions, this feature is confirmed by a theory of crystallization in the presence of an additive. The theory predicts that RG-I has almost no effect on the nucleation phenomenon whereas RG-1I2 enhances this phenomenon. Both RG-l and RG-1I2 inhibit crystal growth by adsorption on crystal growth sites, as contirmed by single crystal growth experiments.</p><p style="text-align: justify;">Red wine tendency to be more difficult to stabilize versus KHT crystallization by cooling than white wine is due to the concentration in RG-II and in total polyphenols : low RG-II content in white wine accelerates crystal appearance whereas high RG-Il content in red wine slows crystal appearance. Thus it intensifies the inhibition due to the high total polyphenol content in red wine.</p><p style="text-align: justify;">Mannoproteins extracted from yeast cell walls inhibit KHT crystallization far more than yeast mannoproteins present in wine. However, their efficiency is reduced as temperature is lowered.</p>

The role of polysaccharides on the grape must ultrafiltration performance

“…For instance, their ability to interact with tannins to inhibit their aggregation, maintaining the stability of colour (Riou et al, 2002) and in red wines the increase of smoothness and body (Guadalupe et al, 2010). As already stated, another important property is their ability to act as protective colloids, their contribution to protein stability (inhibition of protein haze in white wines) (Waters et al, 1993) and tartaric stability (inhibition of hydrogen tartrate crystallization, increasing tartaric stability) (Gerbaud et al, 1997;Moine-Ledoux and Dubourdieu, 2002). Also, an important role of RGII, that is under investigation, and include nutritional benefits, is the complexation of divalent cations, to form specific coordination complexes with heavy metals Pellerin et al, 1997).…”

Determination of Must and Wine Polysaccharides by Gas Chromatography-Mass Spectrometry (GC-MS) and Size-Exclusion Chromatography (SEC)

“…Wine polysaccharides play a critical role in stabilizing other molecules in solution, preventing or limiting aggregation and flocculation and thereby haze formation (Waters et al 1994;Moine-Ledoux and Dubourdieu 1999;Dupin et al 2000;Lomolino and Curioni 2007;Schmidt et al 2009) and tartrate salts crystallization (Gerbaud et al 1997;Moine-Ledoux and Dubourdieu 2002). Wine polysaccharides have also been described for their detrimental role in filterability (Belleville et al 1991(Belleville et al , 1992Vernhet et al 1999), their influence on the fermentation flora (Guilloux-Benatier et al 1995;Guilloux-Benatier and Chassagne 2003), and their interaction with aromatic compounds (Dufour and Bayonove 1999;Chalier et al 2007) and other molecules responsible for wine flavor, color, and foam (Riou et al 2002;Vidal et al 2004;Poncet-Legrand et al 2007;Martínez-Lapuente et al 2013).…”

“…It has been shown that AGP have greater influence on the filtration procedures than MP (Ribéreau-Gayon et al 2006) which are more efficient at reducing protein haze in white wines (Waters et al 1994;Moine-Ledoux and Dubourdieu 1999;Dupin et al 2000). RG-II is a stronger accelerator of hydrogen tartrate crystallization than RG-I, accelerating crystallization at low concentrations and inhibiting it at high concentrations (Gerbaud et al 1996). AGP, on the other hand, have no effect on this phenomenon (Ribéreau-Gayon et al 2006).…”

“…AGP, on the other hand, have no effect on this phenomenon (Ribéreau-Gayon et al 2006). Among the MP classes present in wine, some have been found to act as protective factors with regard to tartrate salts precipitation (Gerbaud et al 1997;Moine-Ledoux and Dubourdieu 1999), and it has also been described that MP can adsorb toxic ochratoxin A from wines (Bejaoui et al 2004;Baptista et al 2004;Ringot et al 2005;Caridi et al 2006) and that the dimer RG-II /boron can form complexes with di-and trivalent cations which could reduce the level of toxic cations in wines (Pérez et al 2003). There are also important differences with regard to the effect of wine polysaccharides on the organoleptic properties of red wines.…”

Equilibrium and Kinetic Parameters for the Sedimentation of Tartaric Salts in Young Wines

“…It is because of the thermodynamics involved, that it requires a long time for the solution to change from supersaturation to a reasonably stable state [7]. Thus, the effi ciency of cold stabilization (the wine cooling performed in interval -4 to -10 ºC) is caused by decrease of the tartaric salts solubility, which determines the creation of an interface between the two phases, a process that requires a lot of interface energy [8]. This step can be accelerated by the addition of cream of tartar (crystal of potassium tartrate), which has the role of crystallization initiator.…”