Various techniques used in winemaking by "controlled supply of oxygen" or "preventing the influence of oxygen". Oxygen uptake takes place when the surface of the grape must or wine comes into contact with air. This applies in particular to all activities where mechanical movement takes place, such as pressing, fining, filtration, deacidification, pumping over and bottling. However, there is also a small supply of oxygen during barrel ageing through the cavities in the wood, as well as during bottle ageing through the cork or other closures. The latter is also deliberately controlled by means of special, oxygen-permeable closures. Absorption is favoured by large liquid surfaces, such as those found in tanks or barrels or with turbulent flow behaviour. The absorption of oxygen is also increased by low temperatures.
The deliberate and controlled contact of grape must and wine with oxygen is achieved using aerate. The process depends on the desired wine type. Dark, tannin-rich red wines are better protected against oxidation by the phenolic compounds than light-coloured, low-tannin red wines and white wines. When making red wines, it is quite common to add oxygen in measured doses. With white wines, on the other hand, the addition of oxygen is prevented or minimised wherever possible in order to increase the shelf life. Certain types of wine, such as port, sherry and Madeira, are produced with oxidative ageing. A new technique is a controlled, minimised oxygen supply into the bottle via special closures (see micro-oxygenation).
For the production of alcoholic beverages, see Champagne (sparkling wines), Distillation (distillates), Spirits (types), Winemaking (wines and wine types) and Wine law (wine law issues).
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