Inert substances (inert = idle, uninvolved) are understood to mean inert substances, which do not participate in certain chemical processes because they contain no oxygen. This is almost all gases (noble gases), except the very reactive oxygen, In viticulture these are for example nitrogen and carbon dioxide which are often used as protective gases against an undesirable oxidation be used in wine containers. This will, for example, the Kahmigwerden (Wine error) prevented. So-called inert gas mixtures are produced by combustion of combustion gases and then contain no oxygen, but nitrogen and carbon dioxide. These mixtures are less expensive than, for example, pure nitrogen, but it is preferred.
There are bottling plants at the bottling before closing the bottle whitespace (Headspace) fill with inert gas to exclude oxidation. This is especially true when using screw caps important because here the amount of oxygen in the space is much larger. In the so-called inner sealing closures, such as cork (regardless of whether it is natural or plastic), sealing under vacuum has been used for a long time, because this prevents excessive pressure in the head space due to the cork being pushed in (excessive pressure could lead to pushing out). The closure under vacuum is now also possible with screw caps. Australia also uses snow-dropping, which adds dry ice (solid carbon dioxide). When the dry ice is in contact with the wine, it evaporates immediately and pushes the air out of the bottleneck. Thereafter, the closure takes place immediately. See also on this topic oxidation. oxygen management and closures,