The ABCs of Cognac Distillation: A look inside the swan’s neck
Cognac is no ordinary brandy. Anyone can make brandy, but Cognac comes only from the Charente region of France, southwest of Paris located on the northern border of Bordeaux. Fermented wine, mostly from ugni blanc grapes grown in six crus (areas), is double distilled in the unique Charentais method. Producers use copper alembic stills as regulated by the Cognac AOC (Controlled Appellation of Origin). Distillation is based on principles of chemistry and physics: When wine is brought to a boil, alcohol and aroma molecules turn to vapor. When cooled, the vapors return to a liquid of alcohol and water. Each Cognac house customizes the distillation process with its unique blend of wine and methods for cutting the best distillate from the process flow. The finished distillate, called eau de vie (water of life), is barrel aged from two years to 60 years or more in oak barrels and slowly evolves into Cognac.
The goal of distillation is to transform newly fermented wine into eau de vie, the mix of aromatic alcohol and water, which ages in barrel into Cognac. This Hennessy display shows the base wine and then the brouillis, the product of the first distillation, named from the phrase le temps se brouille, “it’s clouding over,” because it’s not yet clear. During the second distillation, brouillis is preheated and then boiled again, vaporized and condensed into eau-de-vie at 72 percent alcohol.
At the Calvignac Prulho Distillation production workshop in Jarnac-Champagne near the town of Cognac, traditional Charentais pot stills are handcrafted from German copper. Here is a view of a chaudiere or boiler with the hand tools for hammering. In the background are the chapiteaux or hats which sit on top of the boiler and help direct the aromatic, alcoholic vapors into the col de cygne or piping in the shape of a swan’s neck before they are cooled and condensed into liquid.
A Chalvignac worker pauses before drilling screws through the boiler which will be used to rivet the parts together. In the background a worker prepares to put a natural paint sealant over the chapiteau portion of the alembic still. It takes two years for a worker to learn all the skills to make and assemble these stills. Copper is the classic material to resist corrosion from the acid environment of the wine, impart a neutral flavor and provide good heat transfer.
Hennessy, the largest Cognac producer, runs 19 distilleries and buys eau-de-vie from over 560 other distillers. Here is one section of their R&D distillery in the town of Cognac. The all-important alcohol meters are in a stand at the left. The eau-de-vie is transferred to barrels for aging. As Hennessy Head of the Distilleries Olivier Paultes says, “We look for le bonne goût, the good taste. We smell and taste between 50 and 70 samples every day.”
Cognac houses mark their style during distillation. A key decision is whether to distill fermented wine with the spent yeast material called lees. Eau-de-vie distilled with lees has a fuller mouthfeel from the fatty acids in this organic matter. Look closely at Cognac Frapin wine flowing into their chaudiere for boiling, and you see the darker lees at the bottom of the column. Since Martell Cognac prefers an elegant, more delicate style, the company always distills wine without the lees.
The Charentais double distillation is highlighted in this process control chart at Distillerie de Saint Denis which produces eau-de-vie for Cognac houses. The bruleur (gas burner) is heating the base wine in the chaudiere during the first distillation. The still is producing brouillis, the base for the next distillation. The second distillation is represented by the unlit green bulb labeled brouillis on the chaudiere (boiler pot) image. The first condensed liquids from the still, the têtes (heads), are too alcoholic. The coeur (heart) carries the best aromas and alcohol levels. The queues (tails) have lower alcohol and are usually recycled.
Most distilleries have implemented automated process control, but the human element remains visible throughout the Cognac region. The 24/7 distillation of wine into brouillis and then eau-de-vie occurs from the end of October when the wine from the harvest is fermented until March 31st. Here Francois Charlassier of the Martell distillery team oversees the process. Every day Distillery Director Laurent Nony and the distillery team participate in sensory tests for quality.
Once the wine is heated, the distiller closely monitors the level of alcohol as the product vaporizes and then condenses. The coupe or cut of the heart, in the first distillation is brouillis, and is captured from the distillate flow when it reaches about 30 percent alcohol. When the alcohol falls below 30 percent, the cut is made to process the queues (tails). During the second distillation, the cut for eau-de-vie is made when the liquid measures about 72 percent alcohol.
A frequent manual check of the alcohol content of the distillate flow is made at Martell and the other Cognac houses. Smaller houses such as Cognac Maison Dudognon have no automated controls in their distillery.
Another variable for Cognac houses is the length of the distillation cycle which takes from eight to twelve hours. The heating process can vary by the ambient temperature and type of burner. Gas is most common heat source, but Cognac Maison Dudognon and a few others use less predictable wood and coal. Pierre Burand demonstrates the method his grandfather taught him to check the vapor’s temperature. The family puts wax on the string. If it melts as it descends on the col de cygnet (swan’s neck), the coeur or heart of the distillation—brouillis or eau de vie—will soon reach the alcohol level for the coupe (cut).
Cognac producers are proud of the equipment and production methods in their distilleries. Workers meticulously polish the copper parts and accessories and wax the alembic stills. At Hennessy, the sign, prendre un chiffon pour toucher les cuivres, means “Please use a cloth to touch the copper.” Sweaty handprints can result in 20 minutes of buffing.
Tourism has increased in the Cognac region in recent years. Though “Distiller-For-A-Day” programs are not available, producers explain the distillation process and offer hands-on blending opportunities. New tasting rooms have sprung up at distilleries. At the Camus Master Blender Workshop in the town of Cognac, you can blend and take home your own 500 ml bottle. In the background are examples of the aging process from eau-de-vie to mature Cognac.
An example of an exclusive finished product is Remy Martin Louis X111 made since the 19th century. The Rare Cask 42,6 edition on display at the Remy-Martin Distillery sells for about 18,000 euros (about $20,300) a bottle. Part of the cost is the handcrafted, crystal Baccarat package.
Today Cognac is more than an after dinner sipper. At an ultimate Cognac party at Distillerie de Saint Denis, refreshing cocktails are served. The drink is made from Cognac, the aperitif Pineau de Charentes (a blend of Cognac with unfermented grape juice), Grand Marnier, simple syrup and fresh lemon juice.