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Term for a chemical reaction in which one atom or molecule absorbs (reduces) electrons and another substance releases these electrons (oxidizes). In the narrower sense one refers in connection with oxygen as a reducing agent, the substance that another such. B. oxide (oxygen compound) extracts the oxygen and is itself oxidized. Many substances can be both oxidized and reduced. Whether a substance is reducing agent or oxidizing agent depends solely on the reaction partner. One for the winemaking important stuff is the sulfur where it is used as a reducing agent. It can be used as reductant with oxygen too sulfur dioxide react, but also convert as an oxidizing agent metals in their sulfides.

Reducing agents are those substances that easily release electrons. These include hydrogen, carbon and base metals like iron. magnesium and sodium, The reducing agents are themselves oxidized. Oxidants are those substances that can easily absorb electrons, among others oxygen. chlorine and fluorine. The oxidizing agents are thereby reduced themselves. With the reduction is always always one oxidation connected and vice versa. Both processes together are partial reactions of one redox reaction,

In the winemaking a reduction takes place among other things in the last stage of the fermentation instead, at which acetaldehyde (Alcohol precursor) in ethanol Converted (alcohol) and carbon dioxide is produced (in the initial stage, an oxidation state promotes the required rapid growth of the yeasts ). Most white wines are quite deliberately on reductive expansion, This is necessary because, unlike red wines, they are less protective against oxidation phenols have. After this Press As a rule, the must is therefore sulphurized immediately and fermented under exclusion of air in a steel tank. This prevents unwanted oxidation processes. The effect is splashy. fruity and pure wines. For wine types like sherry and port wine However, it is done consciously oxidative expansion,

A reduction must be made in a controlled manner, as a wine that is kept too close to air can lead to the formation of hydrogen sulfide and thiols (Mercaptans), which leads to reductive notes that as reduction flavors be designated. To a lesser extent, this may be acceptable. With strong concentration that is one wine faults the dreaded sulfurous off (Schwefelböckser). A wine in the bottle (or in an airtight container) is in the reductive state because of the low amount of oxygen in the bottle bottleneck is slowly consumed by reactive processes. See also below oxygen management as well as a complete list of all procedures under winemaking,

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