Winemaking
Concentration methods
Saignée, reverse osmosis, vacuum evaporation and cryoextraction — four ways of removing water, with different consequences.
The short answer
Concentration removes water from must or wine so that everything else becomes proportionally more concentrated. The methods differ in what else they remove, and none of them adds anything that was not already there.
Overview
Concentration is most often used in wet vintages, where rain close to harvest has diluted the fruit.
It is regulated and capped, and it is not universally regarded as legitimate even where it is legal.
Step by step
1 Saignée
Bleeding off a proportion of juice early in a red fermentation, raising the skin-to-juice ratio for what remains. Produces rosé as a by-product. The oldest and simplest method, and the only one that yields a second wine.
2 Reverse osmosis
Forcing wine or must through a membrane that retains larger molecules and allows water through. Also used in reverse to reduce alcohol, and for smoke taint remediation.
3 Vacuum evaporation
Removing water by evaporation at reduced pressure, so it can be done at low temperature without cooking the must.
4 Cryoextraction
Freezing the fruit and pressing while frozen, so the more concentrated fraction is expressed first. Used in Sauternes in wet years, and distinct from ice wine, where the grapes freeze on the vine.
Concentration concentrates everything, including anything undesirable. Where fruit was affected by rot or by underripeness, concentrating it is not a repair.
Sources
Sources consulted
- International Code of Oenological Practices — OIV
- Regulation (EU) No 1308/2013 — Common Organisation of Agricultural Markets — European Union
- WSET educational materials and the Systematic Approach to Tasting — Wine & Spirit Education Trust
More in winemaking
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Fermentation
Yeast converting sugar into alcohol and carbon dioxide — the step that makes wine wine.
Winemaking
How red wine is made
Fermenting grape juice in contact with the skins, which is where colour and tannin come from.
Winemaking
How white wine is made
Pressing the juice off the skins before fermentation, then fermenting the clear juice.