alcohol distillation

Distillation’s History and Evolution Distillation is the chemical process of isolating components from a mixture by changing their phases (liquid to gas) and then altering their relative concentrations. Distillation processes can be applied to virtually all liquids, from water and petroleum to organic compounds like essential oils. Distillation has its origins in Mesopotamia where archaeological excavations revealed crude methods of distillation through terracotta objects found there. The alembic was likely invented around AD 200 – 300 by Egyptian alchemists Maria the Jewess or Zosimo of Panopolis to produce finer essences for perfumes and convert base metals to gold. The Greek term for an alembic was initially translated into Arabic as al-anbiq and then into English as alembic.

First bench stills were thick blown glass retorts coated with clay to moderate the heat of vaporization and prevent cracking or bleeding of glass. They were placed into a boiler of sand, ashes or water bath to maintain optimal conditions for distillation; eventually passing their contents through a condenser separated those with lower boiling points from those with higher ones – collected into fresh collection vessels after which repeated for the remaining fractions.

After the American Civil War, commercial distillation began to emerge at an industrial scale. Rail transportation of grain made distilling more cost-efficient; Aeneas Coffey even created his still in 1830 as an early version of a column still, which allowed distillers to reach higher proof levels more easily than with pot stills.

Alcohol distillation is a delicate and intricate process, demanding the skills and expertise of an accomplished distiller to successfully complete it. At its heart lies producing a faultless distillate; any flaw could jeopardise both quality and acceptability of your final product.

Distillers employ fractional distillation to separate alcohol from its water components in fermentation mixtures, heating until all of it evaporates and collecting the vapor collected – known as fractional distillation – before cooling it and condensing alcohol from water molecules, thus isolating it from other components of spirit production. If there are unwanted components or ‘congeners’ which don’t evaporate with ethanol evaporating they must be separated out using various techniques (for more details please see Harold McGee’s wonderful book On Food and Cooking).

Ethanol has a lower boiling point than water, yet has higher vapor pressure due to its greater mass and surface tension, causing it to evaporate more quickly than water – leading to its composition being made up primarily of lower order alcohols such as propanol, butanol, and amyl alcohols (collectively known as fusel oils).

These volatile aroma compounds produce an unpleasant and bitter flavor. Their fumes numb the nose of distillers, and unless filtered out they alter the flavor of spirit. Therefore, it is vitally important that tasting vessels be selected with care; an engineered tasting vessel can reduce severe ethanol olfactory numbing while improving aroma definition for those evaluating, judging, rating or distilling spirits.