 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Still" – news ·newspapers ·books ·scholar ·JSTOR(August 2021) (Learn how and when to remove this message) |
Astill is an apparatus used todistillliquid mixtures by heating to selectivelyboil and then cooling tocondense thevapor.[1] A still uses the same concepts as a basicdistillation apparatus, but on a much larger scale. Stills have been used to produceperfume andmedicine,water for injection (WFI) for pharmaceutical use, generally to separate and purify different chemicals, and to producedistilled beverages containingethanol.
Sinceethanolboils at a much lowertemperature thanwater,simple distillation can separate ethanol from water by applying heat to the mixture. Historically, acopper vessel was used for this purpose, since copper removes undesirablesulfur-based compounds from the alcohol. However, many modern stills are made of stainless steel pipes with copper linings to prevent erosion of the entire vessel and lower copper levels in the waste product (which in large distilleries is processed to become animal feed).[2] Copper is the preferred material for stills because it yields an overall better-tasting spirit. The taste is improved by the chemical reaction between the copper in the still and the sulfur compounds created by the yeast during fermentation. These unwanted and flavor-changing sulfur compounds are chemically removed from the final product resulting in a smoother, better-tasting drink. All copper stills will require repairs about every eight years due to the precipitation of copper-sulfur compounds. The beverage industry was the first to implement a modern distillation apparatus and led the way in developing equipment standards which are now widely accepted in the chemical industry.
There is also an increasing usage of the distillation ofgin under glass andPTFE, and even at reduced pressures, to facilitate a fresher product. This is irrelevant to alcohol quality because the process starts with triple distilled grain alcohol, and the distillation is used solely to harvest botanical flavors such aslimonene and otherterpene like compounds. The ethyl alcohol is relatively unchanged.
The simplest standarddistillation apparatus is commonly known as apot still, consisting of a single heated chamber and a vessel to collect purified alcohol. A pot still incorporates only onecondensation, whereas other types of distillation equipment have multiple stages which result in higher purification of the more volatile component (alcohol). Pot still distillation gives an incompleteseparation, but this can be desirable for the flavor of somedistilled beverages.
If a purer distillate is desired, areflux still is the most common solution. Reflux stills incorporate afractionating column, commonly created by filling copper vessels with glass beads to maximize availablesurface area.[3] As alcohol boils, condenses, and reboils through the column, the effective number of distillations greatly increases.Vodka andgin and other neutral grain spirits are distilled by this method, then diluted to concentrations appropriate for human consumption.
Alcoholic products from home distilleries are common throughout the world but are sometimes in violation of local statutes. The product of illegal stills in theUnited States is commonly referred to asmoonshine and inIreland,poitín. However, poitín, although made illegal in 1661, has been legal for export in Ireland since 1997. Note that the termmoonshine itself is often misused as many believe it to be a specific kind of high-proof alcohol that was distilled from corn, but the term can refer to any illicitly distilled alcohol.[4]
The dictionary definition ofstill at Wiktionary
| Principles |  | |
|---|---|---|
| Industrial processes | ||
| Laboratory methods | ||
| Techniques | ||