Term (also headspace) for the unoccupied space above the wine level in a container. This occurs especially in wooden barrels due to shrinkage. However, the empty space is not actually empty, but filled with water and alcohol vapour, released carbon dioxide and air (oxygen). To prevent oxidation, refilling with wine of the same type takes place regularly. In the case of steel tanks and also bottles, if necessary, the empty space is filled with inert gas or sealed under vacuum to remove the air (oxygen). The empty space in the neck of the bottle is also an important quality criterion; here, shrinkage indicates a defective closure and thus spoilage; see filling level. The free space above the liquid level, which is common in fermentation containers, is called the rising space. For a list of relevant keywords on this topic, see barrel and barrel types.
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