Decanting

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Decanting red wine in a decanter

The term decanting ( from French: decanter for “to pour, pour”, “clear”, “settle”, or alchemists Latin decanthare , Latin canthus “beak of a jug”) describes the process of separating one or more, more or less separated phases , by pouring or removing from a vessel, the withdrawn phase being called decantate .

In most cases, it is a matter of pouring off or continuously allowing the supernatant clear liquid to run off from a remaining suspension after sedimentation (sediment; German: sediment) or centrifugation . In principle, for example, a hydrocyclone , isotope separation in a gas centrifuge or centrifugal extractors also work according to the principle of decanting.

A device for decanting is called a decanter . In engineering, they are called solid bowl screw centrifuges .

History and shape of the carafe

As early as the 18th century, glass carafes were used to serve wine. However, at that time the often elaborately decorated vessels were developed exclusively from an aesthetic point of view and not according to the best possible shape for the development of the wine aroma. It was important, however, that the carafe is made of pure glass so that the color of the wine comes into its own and can thus be examined.

Modern carafes are designed specifically for their function, with clear shapes predominating. A bulbous carafe with a narrow neck is the ideal vessel for aerating the wine. It should have about twice the volume of the wine bottle to be decanted in order to allow an even absorption of oxygen on the surface of the liquid and to concentrate the developing fragrances directly above the wide wine surface.

Decanting and carafing of wine

A common example of decanting is carefully decanting wine straight from the bottle without stirring up and pouring out the sediment. Two different goals are pursued:

Slow separation of the wine from the sediment (decanting)

A decanting machine for gentle decanting
A carafe with a wide base so that the red wine is aerated

In the case of wines that have formed sediment in the bottle, the function of decanting is to separate the wine from undesirable sediment (“ depot ”) and tartar . The depot is particularly pronounced with red wines due to the high proportion of color and tannins. Since contact with oxygen in the air during decanting can lead to "tipping over", especially with older wines - i.e. to oxidation and spoilage - in such potentially critical cases a narrow decanting carafe with a small air surface area is used or the wine is carefully transferred to another clean bottle. without pouring the depot. To do this, leave a small amount of wine with depot in the first bottle and turn it a little in the final phase in order to bind the depot to the inside of the glass below the neck. In order to clearly see the depot, hold the bottle in front of a bright light source while it is being decanted; traditionally a candle - a lamp or, if in doubt, a sheet of white paper are also suitable.

How long you should decant a wine before drinking it depends on the age of the wine. For older red wines that are ready to drink, ten minutes are usually enough, while a young, strong red wine sometimes needs two hours in the decanter to “ripen” the taste. If you want to speed up the decanting process, you can do this by gently swiveling the carafe.

Further positive side effects of decanting are, on the one hand, that the - possibly disturbing - residual amount of carbon dioxide can escape. On the other hand, unpleasant smells can evaporate through decanting.

With regard to the shape of the decanter, the decisive factor is the size of the surface with which the wine has contact with air and how strong the oxygen exchange is within the carafe. The opening of the decanter towards the top is also important, with a large opening intensifying the exchange of oxygen, while an opening that becomes narrower towards the top allows the oxygen to float over the wine like a cheese dome .

A decanting machine is used for the particularly gentle decanting of red wine , which ensures that it is poured evenly and smoothly. The bottle is placed directly from the storage shelf in the machine in as horizontal a position as possible and after uncorking the bottle neck is carefully tilted down using a hand crank so that the content flows into the carafe and the depot remains in the bottle. This decanting method is used in particular for very old, matured port wine with an extremely fine deposit.

Ventilation of the wine (carafes)

The aim is to bring the wine into contact with air so that its aroma can improve. In particular, young wines that are not yet ready to drink can gain flavor and offer more enjoyment through this process. The carafe used usually has a wide base and the wine therefore has a large surface that allows air contact. It is often worthwhile to carafe red wines from the barrique . This decanting of wines without a depot into a carafe with a wide base is called "carafing" because there is no separation of the depot and wine. The colloquial term “decanter” for the bulbous target vessel is technically incorrect for this reason.

Decanting in chemistry

Decanting is an inexpensive purification method with remarkable efficiency and is therefore often used in qualitative inorganic-chemical analysis . In order to completely separate the solid from a suspension, the decanting is followed by a filtration . The previous decanting accelerates the separation, since filters allow liquids to pass through the faster the fewer solids have to be retained, i. that is, they don't "clog" as quickly.

Efficient decanting is only possible after prior sedimentation; the solid with the greater density must first settle ("sediment") on the bottom.

In the synthesis, a heterogeneous catalyst can - after it has catalyzed a reaction - sediment and the largest part can be separated off by decanting. For complete separation, it is then usually filtered.

Individual evidence

  1. ↑ woxikon.de
  2. ↑ cactus2000.de
  3. ↑ de.bab.la
  4. ↑ Duden
  5. ↑ Andreas Karolis: Technology of the solid bowl screw centrifuge. (PDF; 4.4 MB) Basel 2007, last accessed on June 6, 2012.
  6. ^ André Dominé: Wine . Ed .: Christian Heße, Martina Schlagenhaufer. 1st edition. Tandem Verlag GmbH, Potsdam, ISBN 978-3-8331-4611-4 , p. 47 .
  7. ^ Walter Wittenberger: Chemical laboratory technology. 7th edition. Springer-Verlag, Vienna / New York 1973, ISBN 3-211-81116-8 , pp. 104-105.
  8. ↑ Heinz GO Becker, Werner Berger and others: Organikum. Organic-chemical basic internship. 19th edition. Johann Ambrosius Barth Verlag, Leipzig 1996, ISBN 3-335-00343-8 .

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