Food Encyclopedia

distillation

v. The process of separating a liquid's components by heating it to the point of vaporation and collecting the cooled condensate (vapor that reverts to liquid through condensation) in order to obtain a purified and/or concentrated form. The apparatus that performs distillation is called a still, of which there are two types--pot still and continuous still. The pot still (which in France is called an alembic—sometimes spelled alambic) consists of a copper or copper-lined pot with a large rounded bottom and long tapering neck connected by a copper pipe to a condenser (a cooled spiral tube). As the fermented liquid (wine for brandy, mash for whiskey) in the pot comes to a boil, it vaporizes. The vapor rises up into the still's condenser, where it cools and returns to a liquid state. This condensation (condensate), which has a higher alcohol concentration than the original mixture, is collected in a receiving compartment. However, because alcohol boils at 173.3°F, water boils at 212°F, and a mixture of the two boils somewhere in between, the condensed liquid still contains some water. This means that redistilling (often several times) may be necessary to achieve the appropriate alcohol level—cognac and scotch whisky are distilled twice, for example, while irish whiskey undergoes 3 distillations. In this case, several pot stills may be lined up, distilling the condensate produced by the first pot still through the second pot still, and so on. The pot still, with its painstaking thoroughness, produces distillates that retain the character and personality of their source ingredients. The continuous still was considered revolutionary when it was introduced in 1826. It's also known by several other names: column still, patent still and Coffey still (after a Scottish tax official, Aeneas Coffey, who made major improvements to it in the early 1830s). The continuous distillation process operates by repeatedly recycling a mixture of steam and alcohol until all the spirit is extracted. The continuous still consists of tall copper columns that continually receive cold mash that trickles down and over a series of steam-producing plates. As the alcohol vaporizes, it becomes part of the steam that, as it rises, goes through the liquid flowing down the plates. As the vapor interacts with this liquid, some of the alcohol in the liquid vaporizes and some of the steam converts back to liquid. The vapor is drawn into vents that then take it to a condenser and receiver. If the tower or column has enough plates, a very high level of alcohol concentration can be attained in this one continuous process. Sometimes, two or more towers or columns are used so that higher levels of alcohol or different levels of alcohol concentration can be produced. A single continuous still performs much like the redistilling process with multiple pot stills. The pot still, however, works in relatively small batches, and the continuous still has an uninterrupted flow of incoming material and outgoing product. The continuous still brought mass production to distillers and dramatically expanded Scotland's whisky industry in the 1800s. distillation; distilled spirits; distillate n. The end product of the distillation process. Distilled spirits include brandy, gin, rum, tequila, vodka and whisk(e)y. These liquors are based on cereal grains, fruit and sometimes vegetables, which are fermented (see fermentation) before beginning the distillation process. After distillation, many are flavored in some way, either with added ingredients or by barrel aging or both. In the United States, each type of distilled spirits must meet strict federal standards relating to the ingredients used (which must be FDA approved) as well as how it's made, labeled (to accurately reflect the contents), advertised and sold. See also alcohol.