Modiffications of the tartaric compounds solubility during malolactic fermentation of some red and white wines

Abstract

This scientific paper presents data regarding the tartaric compounds solubility (acid potassium tartrate-KHT and neutral calcium tartrate-CaT) during the malolactic fermentation of some red and white wines concomitantly with evolution of total, volatile and real acidity (pH), as well as of some composition characteristics: tartaric, malic, lactic and citric acids, potassium and calcium. The trials were conducted on seven different wines from the harvest of year 2007: two white wines obtained from Rkaţiteli and Zghihară varieties and five red varieties (Burgund mare, Băbească neagră, Cabernet Sauvignon, Merlot and Fetească neagră). We have investigated some wines according to their pH values (3.085, 3.135, 3.264, 3.352, 3.422, 3.470, 3.505) and total acidity (9.96, 8.84, 7.88, 7.56, 7.25, 6.94, 6.63 g/L C4H6O6 ). The investigations were carried out in laboratory conditions, during 40 days. For starting the malolactic fermentation, at the end of wine alcoholic fermentation (after 7-15 days), selected malolactic bacteria (SMB) from the Biolact aclimateé (Oenococcus oeni class) assortment were added in wines as leaven. Tartaric compounds solubility was evaluated based on concentration products (PC and PCT), solubility products (KST and KS ), KHT and CaT excess at – 4 °C and of theoretical saturation temperatures (TTS) of KHT and CaT. During the malolactic fermentation we found modifications of tartaric compounds solubility, due to pH values increase. Generaly, increase of concentration values of acid tartrat and neutral tartrat ions takes place, that induce higher values of concentration products, with a direct implication in increase of theoretical saturation temperatures. Excess of KHT and that of CaT, calculated for temperature of -4 ºC (refrigeration temperature of wines) had a different evolution: that of potassium acid tartrat diminshed (as normally), and that of calcium neutral tartrat increased, contrary to a normal evolution of this in similar processes. Obtained data can be useful for specialists in oenology practice for a more rigurously control of wines during the malolactic fermentation and afterwards.