🥃 Rectification

Rectification is the continuous purification of alcohol in a column: vapour condenses on the plates again and again and evaporates again, while the lighter fractions rise. This gives ethanol of roughly 96% ABV. Rectified spirit has almost no smell or taste of its raw material, which is why it is called neutral.

Principle. In the column apparatus, which the Oxford Companion describes as a 19th-century invention, distillation runs continuously rather than in batches. Each plate of the column collects increasingly strong condensate. This is not simply repeated distillation in a pot still, but a counter-flow of vapour and liquid that evens out the composition. The more plates the column has, the purer the result.

Limit. Ethanol and water form an azeotrope, so ordinary distillation cannot go much above about 95.6% by mass, roughly 97% ABV. The OIV international code defines rectified spirit of agricultural origin as containing at least 96 parts of ethanol per 100 parts of spirit at 20 °C.

Use. Regulation (EU) 2019/787 allows vodka and gin based on ethyl alcohol of agricultural origin. Neutral spirit also goes into liqueurs, bitters and the fortification of wine, as in port. Pot-still distillates, by contrast, keep the aroma of the raw material, as described on the distillation page.

Why this matters to you. Neutrality does not mean safety: it is the same ethanol that causes intoxication. Look for the category and strength on the label. The WHO reminds us that there is no safe level of alcohol consumption.