Glossary A

AAU - Alpha Acid Units

A measurement of bitterness. AAU = hop AA% x Ounces added to the boil. This formula does not consider wort gravity, boil time and so on.

Abbey Ale

A strong beer brewed traditionally by Belgian abbeys for the brothers to enjoy as "liquid bread" during their Lenten fasting.

Absolute ALCOHOL

The total amount of alcohol contained in a beverage. Ted Goldammer and Apex Publishers.

ABSORPTION

Assimilation of molecules or other substances into the physical structure of a liquid or solid without chemical reaction.

ACETALDEHYDE

A volatile compound derived from the degradation of sugars during fermentation through decarboxylation of pyruvic acid. It decreases as the fermentation progresses and as the beer ages.

ACETIC ACID

A by-product of yeast metabolism that forms through oxidation of alcohols during the fermentation process giving the beer a vinegar taste and smell.

ACETOBACTER

A microorganism that turns ethyl alcohol to acetic acid during fermentation.

ACHROODEXTRINS

Simple "border" dextrins, from the reduction of starch (amylopectin) by alpha amylase; negative reaction with iodine.

ACID

Any compound that yields hydrogen ions (H+) in solution having a pH lower than 7.0. Also used to refer to a beer exhibiting a sour acidic smell or flavor.

ACIDITY

Refers to the pH of the water when the pH measures less than 7.0. An increasing hydrogen-ion concentration leads to increasing acidity as the pH decreases from 7.0.

Acidic

A predominance of sourness.

Adjuncts

Starches, other than malted barley and wheat, such as corn, rice, and sugar, which dilute the flavor and character of the malt and function as cheap fermentable sugars. Samuel Adams' beers contain no adjuncts.

Aftertaste

The taste, odor and tactile sensations that linger after the beer has been swallowed.

Airlock (also fermentation lock)

A small devices, partially filled with water, that is inserted into the top of a closed fermenting vessel to allow CO2 from the fermentation process to escape without allowing oxygen or microorganisms in. CO2 escapes an airlock by bubbling through the water; the rate at which fermentation is proceeding can be estimated by the rapidity of an airlock's bubbling.

Alcohol

A synonym for ethyl alcohol or ethanol.

Alcohol by Volume

A measure of the amount of alcohol in beer; used as a primary measure in Canada. The measure of the amount of space the alcohol in a beer takes up as a percentage of total space.

Alcohol by Weight

A measure of the amount of alcohol in beer; used as a primary measure in the U.S. The measure of the amount of weight the alcohol in a beer has as a percentage of total weight.

Alcohol by volume

Amount of alcohol in beer expressed as a percentage of total beer volume.

Ale

A classification of beer styles. A style made with a top fermenting yeast, ales generally are hearty, robust, and fruity.

ALTBIER (German)

Top-fermenting brew. Copper in color, mashed only from barley malt, fermented from a single-cell yeast and cold-conditioned, with an alcohol content of 4.5% - 4.7% by volume. Put simply an Altbier has the smoothness of a classic lager with the flavors of an ale. A more rigorous definition must take account of history. Ale brewing in Germany predates the now predominant lager production. As the lager process spread from Bohemia, some brewers retained the top fermenting ale process but adopted the cold maturation associated with lager. Hence the name 'Old Beer' (Alt means old in German). Altbier is associated with Dusseldorf, Munster, and Hanover. This style of ale is light to medium-bodied, less fruity, less yeasty, and has lower acidity than a traditional English ale. In the US some amber ales are actually in the alt style.

Aroma Hops

Hop varieties that are chosen for their aroma contribution to the beer. Noble hops are classified as aroma hops.

Astringent

Having tannic, sour notes, often due to boiling the grains, overly long mashes, or sparging with hard water.

Attenuation

The degree to which the yeast ferments the wort during the brewing process. See also (FINAL DEGREE OF ATTENUATION, REAL ATTENUATION)