THE INFLUENCE OF YEAST RACES ON THE AROMA-FORMING SUBSTANCES OF TABLE WINES

Abstract

Wine is a product of biochemical transformations, compounds present in grape juice, by controlled alcoholic fermentation, that is, effervescence. Grape and yeast enzymes play a key role in the processing of grapes and the preparation of wine, influencing all biotechnological processes of winemaking. Adding liquid or dry active yeast to the wort allows better control of the fermentation process. Under the influence of these yeasts, sugar is converted mainly into alcohol or carbon dioxide, but the yeast itself during fermentation produces many molecules (higher alcohols, esters) that affect the aroma and taste of wine. These transformations take about two weeks and lead to a significant increase in temperature, which must be regulated, not allowing it to rise above 18-20°C: otherwise, some of the aromatic substances may evaporate and the fermentation process itself will stop. The amount of yeast that determines the correct and complete fermentation depends both on the quality of the wort itself, and on the more or less prolonged access of air, the ambient temperature. The air, or rather the oxygen of the air, has a beneficial effect on fermentation as long as there are still many nutrients (sugars) in the wort; as the latter are consumed, extremely small yeast cells are formed, which persist for a long time in the form of turbidity. The rapid course of fermentation can be greatly facilitated by the periodic stirring of yeast, which, settling to the bottom, lose direct contact with nutrients — the lower layers almost do not function. You can mix the wort mechanically or by adding healthy whole grapes to it; in this case, the wort is constantly and automatically mixed: the berries, rising up in the fermenting liquid, carry the yeast with them. In order to speed up the fermentation, the wort is sometimes ventilated, that is, air is introduced into it, by mixing. This article shows the influence of the yeast race on the fermentation dynamics of white grape must, the composition of organic acids and aroma-forming components. The races that ensure the production of highquality wine materials are identified.