Reduction (wine)
Reduction is a chemical reaction during fermentation during winemaking , in which acetaldehyde (ethanal) is hydrogenated into ethanol by alcohol dehydrogenase .
A wine that is hermetically sealed is in a reductive state, since every reaction uses up available oxygen and thus restricts change. This state of reduction may be desirable towards the end of fermentation so that carbon dioxide and alcohol are produced from the acetaldehyde . This reduction state is also desirable during the entire development of the wine, since the reductive development protects the wine from oxidation . Especially with white wine, this has a direct influence on the aroma and thus on the style and quality of a wine. The color of the wine is also determined by this, as the iron-containing pigments and dyes contained in the wine can be oxidized.
However, if the reductive state is too strong, it can have negative effects on a wine. These can occur in particular with airtight red wine , as the reduction can lead to polymerization of tannins and polymer pigments. Such a wine can then have an unclean, diffuse taste. Its smell is characterized by reduced sulfur compounds such as hydrogen sulfide , sulfides and thio alcohols (mercaptans). Ventilating the wine can help here and bring it back into balance. This can be achieved, for example, by careful tapping , in which a little oxygen gets into the wine through controlled air contact , which, as an oxidizing agent, can prevent the reduction of many volatile sulfur compounds.
Even when serving, the reduction can be compensated for by dedicated ventilation when caraffing or swirling in wine glasses , which can have a positive effect on their smell and taste with some wines.
literature
- Helmut Hans Dittrich, Manfred Großmann: microbiology of wine. 3rd revised edition. Ulmer, Stuttgart 2005, ISBN 3-8001-4470-0 ( Handbook of Food Technology ).
- Gerhard Troost : Technology of Wine . 6th revised edition. Ulmer, Stuttgart 1988, ISBN 3-8001-5816-7 ( Handbook of Food Technology ).