Non-combustible, colorless and odorless, acidic gas (also carbon dioxide) with the molecular formula CO 2. Colloquially, carbon dioxide is very often falsely as carbonic acid designated. The gas is produced in all combustion processes and also in the respiration of animal and human beings. It also occurs in volcanic rocks and in great depths of the earth. Although in the atmosphere it accounts for only a small fraction of 0.039 percent by volume, this tiny amount is indispensable for all life, because it has been found by the plants in the photosynthesis needed and while the oxygen is formed. Since industrialization, the share has risen by about 25% due to the so - called greenhouse effect, which is directly related to the climate Change stands. The proportion is larger (probably due to the larger land mass) in the northern hemisphere.
Carbon dioxide dissolves in liquids as well as in wine depending on pressure and temperature. When the solution is formed by reaction with water in the smallest amount of only 0.2% and carbon dioxide. However, by far the largest part, at more than 99%, is the carbon dioxide dissolved in the wine (which does not produce any carbonic acid), which is combined with the actual carbonic acid as "free carbonic acid". In the growth of vine is made from carbon dioxide and water sugar in the grapes educated. In the fermentation will then the sugar in carbon dioxide and alcohol transformed. At 1.98 g / l, carbon dioxide is about 1.5 times heavier than air. Therefore, there is danger of suffocation in the fermentation cell if the gas is not removed by means of exhausters. The formation of carbon dioxide is through lees promoted, as well as by expansion in the stainless steel tank favored. Still wines may contain a maximum of 3 g / l (corresponds to 1 bar at 20 ° C). A sparkling wine must have at least 3.5 bar overpressure (corresponds to 6.5 g / l at 20 ° C). The recommended or prescribed quantities are (measured at 20 ° C):
type of wine
Rec / vorg
Carbon dioxide in g / l
|White wine||recommended||1.2 to 1.5|
|rosé wine||recommended||1.0 to 1.5|
|fresh red wine||recommended||0.5 to 0.7|
|strong red wine||recommended||<0.6|
|Perlwein||required||3 (1 bar) to 5.1 (2.5 bar)|
|sparkling wine (see also under sparkling wine )||required||6.5 (3.5 bar) to 9.8 (6 bar)|
Carbon dioxide is not one of the acids but reinforces one sour Sensation and has great influence on the sensory Properties. in the White wine and rosé wine it is refreshing and lively. If the concentration is too low, especially in white wine, one can hollow (empty) taste impression arise. in the red wine however, it is usually perceived as disturbing because it is the astringent Effect of tannins increased, thereby sharp Taste impression arises and aromas are masked (covered). For red wines intended for quick enjoyment such as Beaujolais Nouveau arises due to the nature of winemaking a higher proportion and is also desired there. At the sparkling wine is a minimum amount prescribed by law, with very fine bubbles or high Perlfähigkeit important quality criteria are.
Refreshing is useful for white wine below 0.7 g / l and for red wine below 0.4 g / l. In order to achieve a desired level of carbon dioxide in wine, it must be regularly measured and regulated if necessary. An increase or reduction takes place by means of a gassing fitting. For pressure measurement are different methods. Of the OIV becomes titration recommended, which however requires a corresponding laboratory equipment. The simplest method in still wine is the Veitshöchheimer shaking cylinder, which consists of riser, thermometer and conversion table. In the closed graduated cylinder of 100 ml of wine, the carbon dioxide "shaken" and thereby displaced depending on the content of a corresponding amount of wine from the cylinder. Sparkling wine requires special measuring equipment. The pressure in the bottle is determined by means of aphrometer detected.
In addition, there is further application or use of carbon dioxide in winemaking. When so-called impregnation becomes with it Perlwein generated. When using a maceration in the red wine preparation so that the empty space of the container is filled to the extraction intensify the dyes and tannins (see also under Macération carbonique ). By air (oxygen) displacement in containers and bottles is a oxidation protection reached. Furthermore, carbon dioxide is removed by means of a candle frit for the removal of off-flavors such as light sulfurous off (Schwefelböckser) used. And last but not least, carbon dioxide is also used for the neutralization of alkaline cleaning solutions (as used in the purification of bottles and containers) regarding basement hygiene. See a list of all wine ingredients below total extract,