The cut is the moment when the distiller decides to separate the different parts of a distillate. Like a tree that is trimmed so that it gives the finest fruits, the art of distillation is based largely on selection: keeping the best while removing the least desirable fractions. This operation of rectification will intervene several times during the distillation cycle. Take the example of the distillation of cognac, which is carried out in two stages. The first distillation produces a low wine (brouillis), a liquid with an ABV between 27 and 35 percent—undrinkable as such, though it contains all the aromatic components of the final product. The second distillation consists of refilling the pot with the first distillate and heating it again to obtain the unaged spirit.
In distilling, “cutting heads” is to collect the first liters of alcohol flowing from the still after the first rising of vapors into the swan neck. On the first distillation (the low wine), the cut consists of the removal of the heads. On the second distillation, cutting heads proves far more difficult to achieve, for if the first liters give off an unpleasant odor, we also know that this part of the second distillation contains compounds—esters of fatty acids—responsible for the aromatic complexity of the distillate. When is the best time to cut? When is the perfect time to remove unwanted elements while preserving the important organoleptic characteristics? This is where a distiller’s experience and talent come into play. Depending on the year and the quality of the wines, but also the chosen distillation method, the distiller will take 8–20 liters of heads or more during the second distillation. The cutting of heads is usually done at the still using the nose and palate of the distiller. After a few liters, the distiller checks, liter after liter, the arrival of pleasant odors. Once the cutting of heads has been completed, the heart will flow. But the distillation process does not stop there. It is now necessary to separate the heart from the tails by cutting the tails. In cognac, the tails are accounted in two fractions, the “secondes” and the tails, since at the end of the distillation perfumes change again. Animal scents appear, which are called secondes. To properly cut the end of the heart, the distiller will first resort to the ABV indicated by the hydrometer as a first indication. From 66/65 percent ABV on, the distiller will lower the fire under the boiler to slow down distillation. The spirit flows more slowly, and the final selection by the master distiller’s nose is facilitated. There is no remedy for failed selection of that moment, hence the extreme attention paid by distillers to the cuts of the second distillation. With a pot still, the cut is done at the beginning and end of the distillation; the column still completes this process automatically.
Generally, the secondes are put back into the brouillis. The heads and tails return to the wine. However, each cognac distiller has a secret way to work with these elements.
Baudoin, A. Les eaux-de-vie et la fabrication du cognac. Paris: J. B. Baillière et fils, 1893.
By: Alexandre Gabriel