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This work was aimed at optimizing a rapid and reproducible conductivity test for the evaluation of wine tartaric stability, in order to improve the practices for the prevention of tartaric precipitations during bottle aging. The test consists in measuring the drop of conductivity in wines kept under stirring for a fixed time, at low temperature, after the addition of micronized potassium bitartrate crystals (KHT). An experimental design was planned to study three factors affecting the test: temperature, duration and dose of added potassium bitartrate. A standard protocol was defined to produce a micronized potassium bitartrate starting from available commercial products, since the dimensions of the crystals can affect the final conductivity values. After the choice of the best conditions the method was validated. Two different stability thresholds were defined for white wines and for red/ rosé wines by comparing the results of the mini-contact test with those of the cold test. [ABSTRACT FROM AUTHOR]

All additives used to stabilize wines against the precipitations of potassium bitartrate have some limits: metatartaric acid (MTA) is effective but very unstable, carboxymethylcellulose is stable and effective in white wines but affects color stability in red wines, mannoproteins have a variable effectiveness depending on wine composition. This work was aimed at testing the effect of new stabilizing products on tartaric precipitations, focusing on the use of Na and K polyaspartate salts (PASPs). The effectiveness of 4 different PASPs and 1 MTA added to red and white wines was compared using the mini-contact test and cold test. The dose effect and the stability of the products over time were also studied. The PASPs showed a similar stabilizing effect and a longer stability over time compared to MTA. PASPs can be considered interesting as additives for wine tartaric stabilization. Further work is in progress to better characterize their enological properties. [ABSTRACT FROM AUTHOR]

Highlights: [•] CMC structural features influence white wine tartaric stabilization. [•] Tartaric stabilization depends on CMC’s degree of substitution and wine matrix. [•] CMC do not change tartaric acid, potassium, calcium and sensory attributes. [•] CMC could be a good alternative to conventional white wine tartaric stabilization. [ABSTRACT FROM AUTHOR]

Abstract: Ion exchange technology has been applied to adjust the pH of red wine and improve its tartaric and oxidative stability. Ion exchange appears to be a useful technique to achieve these objectives. Regarding the effect of ion exchange on organoleptic characteristics and the quality of the obtained wines, a slight decrease in both anthocyanin and tannin contents was observed along with a small drop in the aromatic content. However, the treated wines had lower hue and higher colour intensity and gave better punctuations in the sensory evaluation. These results confirm that ion exchange is an interesting technique for application in red winemaking. [Copyright &y& Elsevier]

• CMC is a good stabilizer of red wines with tartrate instability. • The higher CMC degree substitution the higher CMC stability efficiency. • CMC doesn't change red wine tartaric acid, phenolic compounds and sensory profile. • CMC doesńt decrease the colouring matter stability of red wines. In this work, the effect of carboxymethylcellulose structural features on the efficiency to prevent potassium hydrogen tartrate precipitation in red wines and on the phenolic composition, chromatic characteristics and colouring matter stability was studied. The degree of substitution of carboxymethylcellulose was important for its efficiency in highly unstable wines. Application of carboxymethylcellulose doesn't result in a significant change in the phenolic, monomeric anthocyanin composition, colour intensity, and chromatic characteristics of red wines. Sensory analysis also showed that carboxymethylcellulose doesn't have a significant impact on wine sensory attributes. Carboxymethylcellulose doesn't decrease the colouring matter stability. The use of turbidity for evaluating the colouring matter stability of wines has severe drawbacks as the turbidity value measured might not be related to the amount of suspended material. Therefore, the application of carboxymethylcellulose in red wines is efficient in increasing tartaric stability without impacting on the phenolic composition, sensory characteristics, and colouring matter stability. [ABSTRACT FROM AUTHOR]