Attenuation (brewing)
Encyclopedia
In brewing attenuation is the percentage that measures the conversion of sugar
s into alcohol
and carbon dioxide
by the fermentation
process. The percentage is calculated by comparing weight or specific gravity
of the extract before and after fermentation.
This formula works with extract given in weight percentages or degree Plato. Extract refers to all the non water substances (sugars, dextrins, proteins, vitamins, minerals, etc.) that are present in the wort. The percent extract or Plato scale is a measure in percent of how much of the wort’s weight is extract. Since, at least in the wort and beer gravities that most brewers work with, an almost linear relationship between (specific gravity - 1) and extract percentages exists, the above formula can also be expressed as:
for brewers who prefer to work with specific gravity.
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s into alcohol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
by the fermentation
Ethanol fermentation
Ethanol fermentation, also referred to as alcoholic fermentation, is a biological process in which sugars such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products...
process. The percentage is calculated by comparing weight or specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
of the extract before and after fermentation.
- Attenuation = 100 % * (starting extract - current extract) / (starting extract)
This formula works with extract given in weight percentages or degree Plato. Extract refers to all the non water substances (sugars, dextrins, proteins, vitamins, minerals, etc.) that are present in the wort. The percent extract or Plato scale is a measure in percent of how much of the wort’s weight is extract. Since, at least in the wort and beer gravities that most brewers work with, an almost linear relationship between (specific gravity - 1) and extract percentages exists, the above formula can also be expressed as:
- Attenuation = 100 % * (starting gravity - current gravity) / (starting gravity - 1)
for brewers who prefer to work with specific gravity.