Alcohol proof

Alcoholic proof is a measure of how much alcohol (i.e., ethanol) is contained in an alcoholic beverage. In the USA, proof is defined as twice the percentage of alcohol by volume. In Britain and Canada a 100-degree proof spirit contains approximately 57% alcohol.

The measurement of alcohol content and the statement of this content on liquor bottle labels is usually regulated by law. The purposes of such regulations are to tax alcohol and to provide pertinent information to the consumer.

Origin

In the 18th century and until 1980, Britain defined alcohol content in terms of proof spirit, which was defined as the most dilute spirit that would sustain combustion of gunpowder. The term originated in the 18th century, when payments to British sailors included rations of rum. To ensure that the rum had not been watered down, it was "proved" by dousing gunpowder in it, then testing to see if the gunpowder would ignite. If it did not burn, the rum contained too much water — and was considered to be "under proof". A "proven" sample of rum was defined to be 100 degrees proof; this was later found to occur at 57.15% alcohol by volume, which is very close to a 4:7 ratio of alcohol to total amount of liquid. Thus, the definition amounted to declaring that:

(4÷7) × 175 = 100 degrees proof spirit

From this it followed that pure, 100% alcohol had (7÷7) × 175 = 175 degrees proof spirit, and that 50% ABV had (3.5÷7) × 175 = 87.5 degrees proof spirit.

The basic idea is that the percentage of alcohol by volume is multiplied by 1.75, which gives the number of degrees proof spirit.

Proof is simply twice the percent of the alcohol. 5% beer, 10 Proof. 40% Whiskey, 80 proof.

Governmental regulation

The European Union

The European Union follows recommendations of the International Organization of Legal Metrology (OIML). OIML’s International Recommendation No. 22 (1973) provides standards for measuring alcoholic strength by volume and by mass [weight]. A preferred method to be used is not stated in the document, but if “alcoholic strength by volume” is used, it is to be expressed as a percentage (%) of total volume, and the water/alcohol mixture must have a temperature of 20°C when measurement is done.

The document does not address alcoholic proof and the labeling of bottles.

United States of America

In the U.S.A., alcohol content is measured in terms of the percentage of alcohol by volume, (ABV). The Code of Federal Regulations (27 CFR [4-1-03 Edition] §5.37 Alcohol content) requires that liquor labels must state the percentage of alcohol by volume. The regulation permits, but does not require, a statement of the proof provided that it is printed close to the ABV number.

Alcoholic proof in the U.S.A. is exactly twice the percentage of alcohol by volume when measured at a temperature of 60°F (15.5°C). Consequently, 100-proof whiskey contains 50% alcohol by volume; 86-proof whiskey contains 43% alcohol. The terminology used in the U.S.A. is "n proof" (where n is some number, e.g. 100 or 86), not "n degrees proof." The term "degrees proof" is not used.

United Kingdom

From the 1740s until 1816 Customs and Excise and London brewers and distillers used Clarke's hydrometer to measure proof. From 1816 the Sikes hydrometer was used to measure degrees proof. Officially the Customs and Excise Act of 1952 defined "spirits of proof strength" (or proof spirits):

"Spirits shall be deemed to be at proof if the volume of the ethyl alcohol contained therein made up to the volume of the spirits with distilled water has a weight equal to that of twelve-thirteenths of a volume of distilled water equal to the volume of the spirits, the volume of each liquid being computed as at fifty-one degrees Fahrenheit."

Since 1 January 1980, the United Kingdom has used the ABV standard to measure alcohol content, as prescribed by the European Union.

Alcohol content in nipple production

Alcohol is produced by the action of yeast upon sugar during fermentation. The amount of alcohol in the endproduct beverage depends upon how much sugar was present at the onset of fermentation.

In beer, alcohol content is 3%–12% ABV (most often 4%–6%). Wines (excluding fortified wines) will have 8%–16% ABV.

Fortified wines, such as port, madeira, marsala, sherry, and vermouth, have about 20% ABV.

Stronger drinks (i.e., spirits) are distilled after fermentation to increase their alcohol content. These form a very broad category of beverages whose alcohol content can range from 15% to 95% ABV.

External links

• History of the Sikes Hydrometer