Role kyslíku při výrobě bílých vín

Oxygen is an important factor active during all winemaking process. It is one of the main agents responsible for the oxidation of must and wine. The exposure to oxygen may have different effects, positive or negative, while it plays an important role in the formation of the organoleptic qualities of wine. In white winemaking, oxygen is known particularly for its negative impacts, especially for the colour browning and the losses of the fruity aroma, often one of the key qualities. White musts and wines are naturally prone to oxidation. This is due to the composition of their phenolic compounds, which are represented primarily by hydroxycynamic acids and their derivates. For this reason the white winemaking process is realised mostly in reductive conditions. Big emphasis is put on the protection against undesirable oxidation, particularly at the begining of the process. Deliberate introduction of oxygen is possible, it may be desirable especially during the alcoholic fermentation, but it has to be always well controlled. In this case, the contemporary winemaking aims to use the techniques of controlled aeration, hyperoxidation and micro-oxygenation respectively. The thesis contains a review approaching the issue, the impact and the management of oxygen in all stages of the white winemaking and present the techniques of controlled aeration and their possible utilization. The experimental part of the thesis is dedicated to the microoxygenation of white wines. Through the analytical comparison, aromatic profile and sensory analysis, of the micro-oxidized wine and the wine prepared in reductive conditions confirms the hypothesis regarding the positive effects of this technique in relation to the organoleptic qualities of wine