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The spirits are prepared by distilling white wines in pot-stills, following a two-step procedure, the "distillation charentaise"
Distillation is a very ancient process.The history of distillation itself is very intyeresting, you will find the broad lines later in Cognac Magazine Section. Let us concentrate now on the principle and on the 21st century process.
The principle
The principle of distillation of wines, or of any mixture containing both water and alcohol is easy to understand:
- First, when you heat a liquid, it evaporates; if the vapour meets a
cold surface, it condenses again, just as steam does on the windowpanes
when you bring water to the boil in winter.
- Second, alcohol evaporates more easily than water. So when you heat a
liquid composed of water and alcohol, (such as wine) the first vapours
are highly concentrated in alcohol. As heating or distillation goes on,
the vapours emitted are always more concentrated in alcohol than the
liquid remaining in the boiler. If you control closely the process,
you obtain finally a limpid liquid, which is more concentrated in
alcohol than the liquid was.
In practice, the wines are introduced in big alembics, giant’s marmites where the
heated wines will produce vapours. These vapours progress inside tubes; the tubes finally pass through a
tank full of cold water, and as they are cooled, the vapours condensate
into "eaux de vie", the new-make spirit, limpid and higher in alcohol than the wine was.
The principle is basic, but its application is awfully complicated,
with a lot of varieties in stills: shape of the different parts of the
alembics, size of the alembics, continuous distillation or batch
distillation, heating and cooling procedures….
There are numbers of
practices of distillation throughout the world. The techniques used to
distil grains (for producing gins or whiskies for instance) or cane
juice in the case of rums are not identical. And even when it comes to
distilling wines, each spirits-making area has developed and improved
its own distillation practices.
Sot the shape of the
alembics and the way of running them are specific to a sopirit and a region: the eaux
de vie in Cognac and Armagnac are not produced in the same stills, and
that has a huge influence on the profiles of the eaux de vie. Good news for diversity!
The "distillation charentaise"
The distillers of Cognac use special pot stills called “alambics charentais”.
After years of empirical evolution, the local
regulations have set the rules to distil Cognacs, and they describe
precisely the alembics.
The shape of these alembics has changed during the last centuries, but a 15th century man could perfectly recognise the modern devices.
A charentais pot still is nearly entirely made of copper. Its more spectacular parts, called the “chapiteau” and the “chauffe-vin” raise like huge copper balloons painted in red towards the ceilings of the distilleries, over the brick coffer that contains and isolates the boiler. An alembic is as beautiful as impressive…and functional.
One of the key points in Cognac, specific to cognac versus most other brandies, is that the wines are distilled in two times:
1. The wines introduced in the “cucurbite” are gradually heated, the vapours rise up slowly, swirl in the « chapiteau », and then progress through the swan’s neck and finally condense in the serpentine. The liquid running out is not yet an eau de vie, it is limpid, smelly, and quite low in alcohol (30% alcohol content) ; it is named “Brouillis”
2. This Brouillis will be distilled a second time: the second distillation is called “seconde chauffe “or “bonne chauffe” (literally good heating), because it is only at this step that the eaux de vie are produced. The distiller will separate the “hearts” (now around 70% alcohol content) - the part of the distillate that holds the delicate fragrances of wild flowers and fresh fruits- from the other parts of the liquid: the liquid that flows out of the tap before the heart (the so-called “Heads”) and the rest, collected after the heart, the “Seconds” and the “Tails”, (or feints) with fragrances that are not exactly sought for, such as varnish or goat’s cheese. I must admit, that we, the French, consume strange cheeses that frighten the rest of the planet, but when eaux de vie are concerned, we do not have the same conception of what is acceptable as a flavour…
Separating the hearts from the rest of the liquid is called “coupe” or cutting.
The eaux de vie at this step are absolutely crystalline; we say “Blanches”, which means white, but they look just like water-or vodka. Nevertheless, they are never drunk at that stage in Cognac.
The real process is more complex; if you get into the details, you’ll easily understand how the distiller can influence the structure of the eaux de vie by many ways: using very clear wines or at the opposite distilling wines full of lees (little remains of fermentation yeasts), recycling Heads or/and Seconds in Brouillis or wines, controlling the temperatures of the parts of the pot still, the speed of the liquid…
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