Study of the effect of alcoholic fermentation on the formation of crystal stability of base wines
Changes in the chemical composition of the must and pomace in the process of alcoholic fermentation lead to an imbalance, reflected in the values ??of integral indicators. The aim is to study the transformations of components of the must and pomace in the process of alcoholic fermentation from the point of view of the crystal stability of wines. The dynamics of indicators was investigated in conditions of fermentation of the pomace and must made of 'Cabernet-Sauvignon' grape variety. The contents of sugars, ethyl alcohol, titratable and organic acids (citric, malic and tartaric), potassium ions, integral indicators (pH, electrical conductivity, buffer capacity) were determined. The tendency to crystal formation was determined by the temperature of saturation with potassium bitartrate. The content of molecular and dissociated forms of malic and tartaric acids was calculated depending on the pH values. The two-phase character of the must and pomace fermentation process was established. On the 1st phase of sugar fermentation an increase in the content of titratable acids results due to the dissociation of organic acids along the 1st stage on the back of the enrichment of the medium with hydrogen ions. Mass concentration of tartaric and malic acids and potassium cation during the must fermentation decreases more significantly than during the pomace fermentation, accompanied by a decrease in the temperature of saturation of the medium with potassium bitartrate. The 2nd phase of fermentation is characterized by less change in physicochemical parameters than the 1st: the rate of fermentation and accumulation of ethanol has decreased as well as the content of titratable, including organic, acids and the potassium cation. Ranges ??of some components change regardless the phase of fermentation: the pH value rises; values of electrical conductivity and potassium cation - decrease. Saturation temperature of fermenting media (pomace and must) with potassium bitartrate tends to decrease, allowing to make a conclusion about the stabilizing character of fermentation process.