Oxidation

Oxidation
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Term for the violent reaction or combination of Oxygen with other substances to which the element tends very strongly with all substances. In the Winemaking this is a very important event that will be allowed only in a controlled manner (see also oxidases ). Occur frequently in the form of uncontrolled Wine error on. It's kind of Emperor Napoleon III. (1808-1873) due to that which has been clarified in most cases harmful effects of too much oxygen in winemaking. He commissioned in 1863, the chemist Louis Louis Pasteur (1822-1895) to investigate why so much wine should perish. Pasteur found that too much air, the spread of Acetobacter (Acetic acid promotes bacteria and thus undesirably wine Vinegar is. But he also discovered that small amounts of oxygen can affect the development of wine-positive, it already meets the small amount in a closed bottle, which is referred to as fine oxidation, see below in bottles .

For biological processes such as fermentation run the complex processes with release of energy. In the manufacture of wine, they are mostly annoying or allowed only under controlled conditions. If uncontrolled or not the desired application allowing the oxidation flavor and bouquet substances attacked and often leads to negative changes, which are characterized by Wine error such as Alterston , Brown fraction , firn or unwanted Sherryton . comment The wine loses freshness and age faster. By oxygen can also contact vinegar bacteria and Kahm (yeast) proliferate, which ultimately makes the wine even inedible.

Usually prevents oxygen from the wine-entry or at least greatly. This is in various stages of the winemaking already by spraying the mash with Ascorbic acid and / or by addition of Sulfur dioxide achieved. The fermentation usually takes place in the absence of oxygen, see also anaerobically . This is achieved by closure of the fermenter with a Gäraufsatz , while allowing the resulting carbon dioxide can escape, but no oxygen-entry is possible. Another possibility is the White space of the fermentation container with inert gas (inert gas) to fill. For special wines is the influence of oxygen is very much desired, for example, variants of the Sherry , In Malaga or the Vin Jaune .

Some manufacturers promote the must before fermentation, as this particular flavor substances are released in certain white wines such as Chardonnay a certain amount of oxidation. The metered supply of oxygen or air to the must or wine in various stages of winemaking is called Ventilation (Venting). A relatively new procedure is Mikrooxigenation (Including hyper-or Makrooxigenation, the term is often used micro-oxidation is not correct). All the methods in which one allows for controlled oxidation of more or less, are called oxidative removal . The prevention or restriction as reductive removal known. An oxidation is, however, only with a simultaneous Reduction possible, see also under redox .