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Alcohol by volume (abbreviated as ABV, abv, or alc/vol) is a standard measure of how much alcohol (ethanol) is contained in an alcoholic beverage (expressed as a percentage of total volume). It is defined as the number of millilitres of pure ethanol present in 100 millilitres of solution at 20 °C. The number of millilitres of pure ethanol is the mass of the ethanol divided by its density at 20 °C, which is 0.78924 g/ml. The ABV standard is used worldwide.
Mixing two solutions of alcohol of different strengths usually causes a change in volume. Adding pure water to a solution less than 24% by mass causes a slight increase in volume, but mixing solutions above 24% causes a decrease in volume. More information on the phenomenon of volume changes due to mixing dissimilar solutions is discussed in the article on partial molar volume.
|It has been suggested that this article be merged into Alcoholic_beverage#By_alcohol_by_volume_.28ABV.29. (Discuss) Proposed since April 2014.|
Details about typical amounts of alcohol contained in various beverages can be found in the articles about them.
|Fruit juice (naturally occurring)||less than 0.1%|
|Chicha||1%–11% (usually 1%–6%)|
|Beer||2%–12% (usually 4%–6%)|
|Barley wine (strong ale)||8%–15%|
|Wine||9%–16% (most often 12.5%–14.5%)|
|Sake (rice wine)||15% (or 18%–20% if not diluted prior to bottling)|
|Fortified wine||15.5%–20% (in the European Union, 18%–22%)|
|Soju||17%–45% (usually 19%)|
|Shochu||25%–45% (usually 25%)|
|Ruou (Vietnamese liquor)||27%-38%|
|Mezcal, Tequila||32%–60% (usually 40%)|
|Vodka||35%–50% (usually 40%, minimum of 37.5% in the European Union)|
|Brandy||35%–60% (usually 40%)|
|Whisky||40%–61% (usually 40% or 43%)|
|Centerbe (herb liqueur)||70%|
|Pálinka||42%–86% (legally in Hungary 48%–51%)|
|Ţuica||45%–60% (usually 52%)|
|Neutral grain spirit||85%–95%|
Another way of specifying the amount of alcohol is alcohol proof, which in the United States is twice the alcohol-by-volume number, while in the United Kingdom it is 1.75 times the number (expressed as a percentage). For example, 40% abv is 80 proof in the US and 70 proof in the UK. However, since 1980, alcoholic proof in the UK has been replaced by abv as a measure of alcohol content.
In the United States, a few states regulate and tax alcoholic beverages according to alcohol by weight (abw), expressed as a percentage of total mass. Some brewers print the abw (rather than the abv) on beer containers, particularly on low-point versions of popular domestic beer brands.
At relatively low abv, the alcohol percentage by weight is about 4/5 of the abv (e.g., 3.2% abw is equivalent to 4.0% abv). However, because of the miscibility of alcohol and water, the conversion factor is not constant but rather depends upon the concentration of alcohol. 100% abw, of course, is equivalent to 100% abv.
During the production of wine and beer, yeast is added to a sugary solution. During fermentation, the yeast organisms consume the sugars and produce alcohol. The density of sugar in water is greater than the density of alcohol in water. A hydrometer is used to measure the change in specific gravity (SG) of the solution before and after fermentation. The volume of alcohol in the solution can then be calculated.
The calculation for beer is:
Where 1.05 is the number of grams of ethanol produced for every gram of CO2 produced, and .79 is the density of ethanol,
However, many brewers use the following formula: