# Alcohol content

The alcohol content or degree of alcohol is the proportion of pure alcohol (i.e. ethanol ) in the total amount of a mixture. In the case of alcohol-water mixtures or alcohol products, it is given as the volume concentration of pure alcohol at 20 degrees Celsius ( Section 2 (4) of the Alcohol Tax Ordinance ), usually in percent by volume (abbreviated unit symbol: % vol. Or vol .-% ), earlier units were degrees Stoppani , Grad Tralles , Grad Gay-Lussac and Grad Sikes. Since alcohol has a much lower density than water, the volume percentage is higher than the weight percentage . The determination of the alcohol content is called alcoholometry .

## Legal labeling requirement

The alcohol content in beverages must be specified in the European Union according to Annex XII of the EU Food Information Regulation (LMIV), in Germany previously according to § 7b of the Food Labeling Regulation (LMKV), as a volume percentage with a maximum of one decimal place, followed by "% vol" be; the percentage may be prefixed with "alcohol" or "alc.". Instead of "Alk.", The LKMV provided for "alc." The actual alcohol content may have the following deviations (Annex XII LMIV):

• Beer (under CN code 2203 00) with an alcohol content of up to 5.5% vol, as well as fermented beverages made from grapes under CN code 2206 00 that are not products within the meaning of the Wine Act : 0.5% vol
• Beers with an alcoholic strength of more than 5.5% vol, foaming drinks made from grapes falling within CN code 2206 00, cider , perry, fruit wine and similar drinks made from fruits other than grapes, whether or not sparkling or foaming; Mead / mead : 1.0% vol
• Drinks with pickled fruits or parts of plants: 1.5% vol
• other drinks with an alcohol content of more than 1.2 percent by volume: 0.3% vol

The mere requirement to indicate “volume percent”, however, does not yet determine whether the volume concentration or the volume fraction (or even the volume ratio ) is to be indicated, cf. # Examples of alternative salary information .

## Examples of alcohol levels

Alcohol content of some alcoholic beverages
drink Alcohol content
in percent by volume
Alcohol-free beer 0-0.5
Light beer 2.0-3.2
4.5-5.4
Full beer 4.3-5.7
Bock beer 5-12
Burgundy , Bordeaux 10 -14.5
Champagne , sparkling wine 10 - 12 , 8
Wormwood 14.5-21.9
Sherry , port , Samos 15 - 22
Brandy 36 - 45
liqueur 11-55
rum 37.5-80

## Determination of alcohol content

All salary values that contain the volume term are temperature-dependent. A clear indication of concentrations, volume proportions and volume ratios therefore also includes naming the associated temperature. In the case of alcoholic beverages, this concerns the volumes of the ethanol contained, the water contained and the drink as a mixture. The ordinances stipulate that the alcohol content must be determined at 20  ° C. This indicates ("indicates" indicates here that the texts are unclearly formulated and offer certain room for interpretation) that the statement that one liter of the drink contains 40%, i.e. 400  milliliters (= 40 cl) of alcohol, should be understood as follows: At 20 ° C, one liter of the drink contains an amount of substance or mass of alcohol that would also take up a volume of 400 milliliters at 20 ° C. The relevance of the temperature information is demonstrated / discussed under #Examples for alternative content information . - In practice, it is probably even more important that the direct determination of the alcohol content of a sample by completely “filtering out” ( distilling ) and then measuring the alcohol would be far too time-consuming. Instead, one makes use of the fact that the density of an aqueous ethanol solution is lower, the higher its ethanol content, determines the density of the mixture simply based on how deep a test specimen sinks into the mixture ( Archimedes principle ) and concludes from the measurement result on the alcohol content. However, the relationship between mixture density and alcohol content also depends on the temperature of the mixture. Some measuring devices are provided with a scale that shows the alcohol content of the mixture directly, but only correctly at a certain temperature. The regulations therefore state that instruments that are calibrated for a correct display at a mixture temperature of 20 ° C must be used to determine the alcohol content .

## Alternative salary information

### Alternative salary sizes

The article DIN 1310 and content information offer in addition to "partial volume to total volume" (volume concentration) at least 12 further possibilities to indicate the alcohol content of a liquid. In medical research and practice for the consumption of alcoholic beverages , mass concentration - around g / l - or mass fraction - around g / kg - are still used.

Section 2 (4) of the Alcohol Tax Ordinance allows, in addition to specifying the volume concentration at 20 ° C, the specification “as mass content in percent by mass”. Because of “percent” cannotmean“ mass concentration ”, the outdated expression “ mass percent ” indicates that the already mentioned mass fraction and not “ mass ratio ” is meant. (The text comes from § 3 of the Spirits Tax Ordinance .)

Conversion of a volume concentration of σ at 20 ° C in the mass concentration β at 20 ° C (see there ) are simple, by multiplication with the density ρ  ≈ 0.7893 g · cm -3 of alcohol at 20 ° C: β  =  σ  ·  ρ . In view of the legally permitted inaccuracy of the volume percent information for alcoholic beverages, it makes sense to calculate with 0.8 instead of 0.789 ..., i.e. 800 g / l . For a beer with 5 percent alcohol by volume, i. H. an alcohol volume concentration of 0.05 gives about 40 g / l; with vodka with 40% vol, the result is around 320 g / l.

By adding the mass concentrations weighted with the volumes of alcoholic beverages consumed by a person on a day / evening, the amount of alcohol consumed and thus the (maximum) blood alcohol concentration ("per mille") according to the Widmark formula can be calculated quite easily. For example, two pints of beer at 40 g / l and a quarter of red wine at 100 g / l (12.5% ​​vol) contain a total of 40 +100/4 = 65 g of alcohol. A man  weighing 80 kg can deal with it. The average amount of alcohol consumed daily is also used to assess the health consequences of regular alcohol consumption ( "risk classes" , cancer risk , ...). If 20 to 25 g of alcohol daily is critical (men), one should not drink more than two small pils or a quarter of a liter of wine in the evening . ${\ displaystyle {\ frac {65} {80 \ cdot 0 {,} 68}} \ approx 1 {,} 2}$

The mass fraction w is theoretically calculated from the mass concentration β by dividing β by the density ρ m of the total liquid at 20 ° C:

w = β / ρ m = σ · ρ / ρ m .

However, ρ m does not only depend on the temperature , but (in the case of the mixture with water ), because of the volume contraction, also on the alcohol content itself (which, conversely , can be determined from ρ m ) and can be obtained from a table of empirically determined values. Originally, however, there is only one table that is based on mass fractions (Osborne et al., #Literature ), with which only the volume concentration belonging to w can be calculated using σ  =  w  · ρ m / ρ and “searched” in the other direction got to. The Austrian Pharmacopoeia offers a direct comparison of the proportions by mass and the corresponding volume concentrations at 20 ° C ( #Weblinks ). - The advantage of this difficulty is that the mass fraction does not depend on the volumes and the temperature and is also not affected by the volume contraction (this only comes into play in the relationship to concentrations). The #examples for alternative content information also indicate the correspondence of some mass fractions and volume concentrations, including a summary .

### Alternative unit of measure in the US and UK

In the USA, the old English unit of measurement, proof , is also used ; a degree proof corresponds to half a volume percent. However, under Article 27 of the Code of Federal Regulations , manufacturers of spirits are instructed to declare the alcohol content as a percentage by volume.

Information with “Proof” is also available in Great Britain, but its meaning is more complex - see there .

### Examples of alternative salary information

The following table compares some mass fractions , volume concentrations at different temperatures and volume fractions of ethanol in ethanol-water mixtures at 20 ° C., given in percent.

Mass
fraction
Volume concentration at Volume
percentage at 20 ° C
Sample product
10 ° C 15 ° C 20 ° C 25 ° C 30 ° C 40 ° C
2 2.50 2.51 2.52 2.53 2.54 2.56 2.52 Light beer
4th 4.98 5.00 5.02 5.04 5.06 5.10 5.00 Full beer
10 12.33 12.39 12.44 12.49 12.54 12.63 12.32 red wine
12 14.76 14.82 14.88 14.94 15.00 15.10 14.71 Lower limit for spirits
16 19.59 19.67 19.74 19.81 19.88 20.00 19.41 port wine
33 39.50 39.58 39.66 39.73 39.81 39.95 38.38 vodka
47 54.67 54.74 54.80 54.87 54.93 55.05 52.86 Chartreuse Verte (liqueur)
73 79.50 79.54 79.58 79.61 79.65 79.71 77.37 Stroh Original (Rum)

#### Legend

1. The sample levels are chosen so that the table values ​​from Osborne et al. ( #Literature ), p. 424 f., Can be used without interpolation (therefore, “crooked” volume fractions appear for the example products instead of the usual per mille information ). There, for every whole percentage and certain temperatures  ° C values (index "o" for "Osborne") for the quotient of the corresponding density (index "m" for "mixture") of an ethanol-water mixture, in which ethanol is the mass fraction  % and the maximum density (that is at approx. 4 ° C) of water.${\ displaystyle p}$${\ displaystyle t}$${\ displaystyle \ rho _ {{\ rm {o}} t} (p / 100)}$${\ displaystyle \ rho _ {{\ rm {m}} t} (p / 100)}$ ${\ displaystyle p}$ ${\ displaystyle \ rho _ {\ rm {W}}}$
2. The volume concentration of ethanol to the mass fraction at temperature  ° C is calculated as , where the density of ethanol is at  ° C. For we are and give the (to tens per thousand rounded) result in the column to  ° C in percent. (The legally determined reference temperature of 20 ° C is highlighted in italics. Compared to volume concentration # connections with other content variables , the notation of the variables is slightly modified here.)${\ displaystyle \ sigma _ {t} (w)}$${\ displaystyle w}$${\ displaystyle t}$ ${\ displaystyle w \ cdot {\ frac {\ rho _ {{\ rm {m}} t} (w)} {\ rho _ {t}}}}$${\ displaystyle \ rho _ {t}}$${\ displaystyle t}$${\ displaystyle {\ frac {\ rho _ {{\ rm {m}} t} (w)} {\ rho _ {t}}}}$${\ displaystyle {\ frac {\ rho _ {{\ rm {o}} t} (w) \ cdot \ rho _ {\ rm {W}}} {\ rho _ {{\ rm {o}} t} (100 \, \%) \ cdot \ rho _ {\ rm {W}}}} = {\ frac {\ rho _ {{\ rm {o}} t} (w)} {\ rho _ {{\ rm {o}} t} (100 \, \%)}}}$${\ displaystyle t}$
3. From the mass fraction , the volume concentration (as before) and, analogously, the associated volume concentration of the water at 20 ° C, the volume fraction of ethanol at 20 ° C results as - if - where the density of water is at 20 ° C. For we are and enter the result as a percentage.${\ displaystyle w}$${\ displaystyle \ sigma _ {20} (w)}$${\ displaystyle {\ frac {w / \ rho _ {20}} {w / \ rho _ {20} + (1-w) / \ rho _ {\ rm {w}}}} = \ left (1+ \ left ({\ frac {1} {w}} - 1 \ right) \ cdot {\ frac {\ rho _ {20}} {\ rho _ {\ rm {w}}}} \ right) ^ {- 1}}$${\ displaystyle w> 0}$${\ displaystyle \ rho _ {\ rm {w}}}$${\ displaystyle {\ frac {\ rho _ {20}} {\ rho _ {\ rm {w}}}}}$${\ displaystyle {\ frac {\ rho _ {{\ rm {o}} 20} (100 \, \%)} {\ rho _ {{\ rm {o}} 20} (0 \, \%)} }}$

#### Conclusion

1. For each mass fraction , the volume concentration between 10 and 40 ° C increases almost linearly with temperature. For light beers, however, 5 degrees only make up about a tenth of a thousandth point, for full beers 1/5 ‰, for red wine a magnitude of half a per mill. In the case of spirits, the temperature dependency initially continues to increase; 5 degrees above port wine, in the spirits range, is an order of magnitude of one per thousand point. As the alcohol content increases, the temperature dependency decreases again and is only as pronounced in spirits known as 80% as in red wines. The differences are far below the error tolerances for labeling .
2. The contraction in volume when mixing alcohol and water suggests that the volume fraction of ethanol in a mixture of a volume of alcohol with a volume of water is smaller than the associated volume concentration at the same temperature, the volume of the mixture being from the initial volumes and ; the quotient of the two quantities is a measure of the volume contraction. In the example of 20 ° C, however, the difference in light beer is not even noticeable in tenths of a thousandth point, but it increases - initially - with the alcohol content. In red wine it makes up a full per thousand point, but is still below the error tolerance for labeling. In the case of port wine, the difference exceeds the statutory error tolerance of 0.3%. With brandy a difference of one percentage point is exceeded, with higher alcohol contents there is a difference of more than 2 percentage points, but it is now "slowed down". On the way to 100%, it finally has to go back again, which is not yet visible in the examples.${\ displaystyle {\ frac {V} {V + V _ {\ rm {w}}}}}$${\ displaystyle V}$${\ displaystyle V _ {\ rm {w}}}$ ${\ displaystyle {\ frac {V} {V _ {\ rm {m}}}}}$${\ displaystyle V _ {\ rm {m}}}$${\ displaystyle V}$${\ displaystyle V _ {\ rm {w}}}$${\ displaystyle {\ frac {V _ {\ rm {m}}} {V + V _ {\ rm {w}}}}}$
3. Since the quotient of volume fraction and volume concentration remains relatively close to 1, the significantly lower density of alcohol compared to water is reflected in percentages of mass fractions (" mass percent ") that are actually smaller than the associated volume concentrations and volume fractions (" volume percent ") regardless of temperature.