Moët Hennessy USA: Distillation

Each of the parcels is distilled separately if sufficiently large quantities of wine are obtained. If this is not the case, like parcels are combined, in which case the cask is shown as coming from divers sources in a given cru.

The still used in Cognac is known as the Charentais alembic. It is composed of a boiler, the still head, the swan’s neck and the condenser. Sometimes a wine warmer is added to this structure to speed throughput.

The “brouillis”
The boiler (with a capacity of 30 hl) is charged with 25 hl of wine. This wine is heated with a naked gas flame to produce the brouillis, which comes off the still between 40 - 42° ABV. The wine is heated for an hour fifteen minutes, and when it begins to boil the vapors gather in the still head before proceeding through the swan’s neck to the 75 meter long cooling coil.

The first portion to come off the still are known as the “heads” and they are not used. The heads account for 0.5% of the total output of the still. The brouillis or center of the first distillation account for about 9.5% of the wine. The alcoholic content of the brouillis depends on that of the wine. The portion following the brouillis off the still is known as the tails, and they are discarded as well. That which is left in the wine boiler is known as the still wash, and this is recycled after being used to clean the inside of the still.

“La Bonne Chauffe”
During the second distillation (la bonne chauffe), the boiler is charged with the brouillis, which are brought to a boil and distilled a second time. The heads are kept with the heads. The heart comes off the still between 72 - 60° ABV, and they are followed by the seconds. This is a portion of the distillate that could be used, but is recycled by most high quality distillers. The heart of the second distillation is referred to as eaux de vie, since it has not yet been aged into Cognac. This portion comes off the still at a measured rate of one liter per minute. For this reason, a timing of the flow controls the distiller’s actions.

The heads and the tails together are mixed with the wine and re-distilled with the next batch, while the seconds are re-distilled with the brouillis in a proportion of three quarters brouillis to one quarter seconds. This gives a more characterful spirit, while adding the seconds back to the wine gives a more neutral spirit.

Both cycles together require 24 hours to complete, and this distillery can process 300 hl of wine each day, working 24/7 from November through March (the legal limits placed on distillation). Hennessy operates three distilleries, while there are 19 bouilleurs de profession and a large number of bouilleurs de cru or small, independent distillers distilling exclusively their own wine.

In all, nine liters of wine at 9% ABV are needed to produce one liter of EDV at 71% ABV.

Sometimes a wine warmer is used to increase the throughput of the distillery. After the initial distillation, cold wine cannot be put directly into the boiler, since it causes a thermic shock. The wine warmer is thus used for about an hour to bring the next batch of wine up to the temperature of the boiler. This can be a delicate operation, however, since there is a risk of the wine boiling here and essentially beginning a fermentation prior to the end of the preceding distillation. This can lead to the production of undesirable aromas in the EDV.