The alembic is where the alchemy of distillation takes place. An alembic is a piece of equipment for distilling liquids, separating components based on their different boiling temperatures. This technique is fundamental in the production of alcoholic beverages, allowing pure and flavored distillates to be obtained.
Fundamental parts of a still:
- Boiler: In which heat is applied and the initial mixture is heated. In this process, the liquid is heated to boiling temperature.
- Column: Where the vapors accumulate and where the components of the mixture are separated on the basis of their different boiling temperatures. allowing for a purer alcohol.
- Condenser: The vapors are cooled by running cold water, reverting them back to liquid form. During condensation, the vapors interact chemically with the copper, removing unwanted sulphides and catalyzing fruity aromas.
A destilação é um processo físico de separação de compostos com base nas suas diferenças de volatilidade. A volatilidade refere-se ao ponto de ebulição de um composto. A água ferve a 100ºC e o etanol(álcool) tem um ponto de ebulição de 78.4ºC, o que faz com que uma mistura de água e o álcool tenha um ponto de ebulição entre 78.4º e 100ºC. É Importante verificar que o álcool é mais volátil do que a água. Por isso, ao aquecer uma mistura individual dos dois líquidos, a concentração do álcool é mais elevada do que a a mistura líquida original. Se os vapores forem resfriados novamente até a sua forma líquida, o álcool terá uma concentração mais alta do que o líquido original do destilado.
The distillation process usually requires two passes to produce a suitable drink. The first distillate that comes out is usually rich in solvent aromas, esters and aldehydes. This distillate is usually not the tastiest, hence a second distillation, where the distiller will choose which spirit to keep and which to discard or recycle.
It is important to note that the quality of the raw materials is crucial to the final result of the distillate, having a direct impact on its taste and aroma.
In recent years, the biggest advance in stills has been the heating method. The distillers of old had no choice but to put direct heat into the alembic, but today there are other ways of heating it. Despite these advances, some distillers believe that direct heat is essential for the character of their distillate, and have maintained this tradition.
There have also been advances in the equipment that allows monitoring and testing. Today, distillers are also able to assess how the still is working and adjust its distillate. However, despite the advances, stills are limited because they are used in process, first loading, followed by operation and then emptying, after which they are cleaned to repeat the process.
In 1826 Robert Stein invented a still made up of two columns, with the aim of speeding up and improving the distillation process. Later, in 1831, Aeneas Coffey considerably improved the design, which allowed distillers to produce a purer drink on a larger scale. Even then, the quality of the spirits produced was close to what we enjoy today.
Column stills behave like a series of interconnected stills, the columns form a long vertical tube, and each column has bubble plates separating the floors, on each floor there is a pool of wash attached and the holes in the plates allow the value to rise and bubble.
Column stills allow for what is known as fractional distillation, as several different compounds (or fractions) are retained according to their boiling point on different floors of the still, allowing each component of the distillate to be removed from that section of the still. The more floors a column has, the more rectified and pure the final distillate will be.
Referências:
Strickland, M. (2023) Back to Basics: How a pot still works. Whisky Magazine https://whiskymag.com
Difford, S. (2019) Distillation – Pot v column distillation. Difford`s Guide https://whiskymag.com
Stichlmair, J. G., Klein, H., & Rehfeldt, S. (2021). Distillation: principles and practice. John Wiley & Sons.
