Fusel alcohols or fuselol, also sometimes called fusel oils in Europe, are mixtures of several higher alcohols (those with more than two carbons, chiefly

amyl alcohol Amyl alcohols are alcohols with the formula C5H11OH. Eight are known. A mixture of amyl alcohols (also called amyl alcohol) can be obtained from fusel alcohol. Amyl alcohol is used as a solvent and in esterification, by which is produced amy ...

) produced as a

by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be cons ...

of alcoholic fermentation. The word ''Fusel'' is German for "bad

liquor Liquor ( , sometimes hard liquor), spirits, distilled spirits, or spiritous liquor are alcoholic drinks produced by the distillation of grains, fruits, vegetables, or sugar that have already gone through ethanol fermentation, alcoholic ferm ...

". Whether fusel alcohol contributes to

hangover A hangover is the experience of various unpleasant physiological and psychological effects usually following the consumption of alcohol (beverage), alcohol, such as wine, beer, and liquor. Hangovers can last for several hours or for more than ...

symptoms is a matter of scientific debate. A Japanese study in 2003 concluded that "the fusel oil in whisky had no effect on the ethanol-induced

emetic Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, preg ...

response" in the Asian house shrew. Additionally, consumption of fusel oils with

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

suppressed subjects' subsequent taste aversion to alcohol, which suggested subjects' hangover symptoms were lessened, according to the journal.

Usage

Fusel oil and fusel-oil acetates are used in the

lacquer Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity. Asian lacquerware, which may be c ...

industry as high boiling point

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

Compounds

Excessive concentrations of some alcohols other than ethanol may cause off-flavors, sometimes described as "spicy", "hot", or "solvent-like". Some beverages, such as

rum Rum is a liquor made by fermenting and then distilling sugarcane molasses or sugarcane juice. The distillate, a clear liquid, is often aged in barrels of oak. Rum originated in the Caribbean in the 17th century, but today it is produced i ...

whisky Whisky or whiskey is a type of liquor made from Fermentation in food processing, fermented grain mashing, mash. Various grains (which may be Malting, malted) are used for different varieties, including barley, Maize, corn, rye, and wheat. Whisky ...

(especially bourbon), incompletely rectified vodka (e.g. Siwucha) and traditional ales and

cider Cider ( ) is an alcoholic beverage made from the Fermented drink, fermented Apple juice, juice of apples. Cider is widely available in the United Kingdom (particularly in the West Country) and Ireland. The United Kingdom has the world's highest ...

s, are expected to have relatively high concentrations of non-hazardous alcohols as part of their flavor profile. However, in other beverages, such as

Korn Korn (stylized as KoЯn) is an American nu metal band from Bakersfield, California, originally formed in 1993 by James Shaffer, James "Munky" Shaffer, Reginald Arvizu, Reginald "Fieldy" Arvizu and David Silveria, who were members of the band ...

vodka Vodka ( ; is a clear distilled beverage, distilled alcoholic beverage. Its varieties originated in Poland and Russia. Vodka is composed mainly of water and ethanol but sometimes with traces of impurities and flavourings. Traditionally, it is ...

and

lager Lager (; ) is a Type of beer, style of beer brewed and Brewing#Conditioning, conditioned at low temperature. Lagers can be Pale lager, pale, Amber lager, amber, or Dark lager, dark. Pale lager is the most widely consumed and commercially availab ...

s, the presence of alcohols other than ethanol is considered a fault. The compounds involved are chiefly the following: * isoamyl alcohol (isopentanol) * 2-methyl-1-butanol - sometimes called "active"

* isobutyl alcohol - one of the least toxic of the butanols. * 1-propanol Other higher alcohols that can be produced during fermentation include: *

isopropanol Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable, organic compound with a pungent alcoholic odor. Isopropyl alcohol, an organic polar molecule, is miscible in water, ethanol, an ...

(isopropyl alcohol), oxidized to form acetone by

alcohol dehydrogenase Alcohol dehydrogenases (ADH) () are a group of dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of nicotinamide adenine dinucleotide (NAD+) to N ...

in the liver, leading to

ketosis Ketosis is a metabolic state characterized by elevated levels of ketone bodies in the blood or urine. Physiological ketosis is a normal response to low glucose availability. In physiological ketosis, ketones in the blood are elevated above bas ...

when ingested in large quantities. * 1-butanol * 1-pentanol (''n''-amyl alcohol) * 1-hexanol * 2-phenylethanol * tyrosol * tryptophol * methionol

Distillation

During

distillation Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixt ...

, fusel alcohols are concentrated in the feints or "tails" at the end of the distillation run. They have an oily consistency, which is noticeable to the distiller, hence the other name "fusel oil". If desired, these heavier alcohols can be almost completely separated in a

reflux still Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations. It is also used in chemistry to supply energy to reacti ...

. On the other hand, freeze distillation does not remove fusel alcohols. Fusel alcohols can be reduced during

fermentation Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...

by lowering the fermenter's temperature or increasing the oxygen content.

References

External links

* {{Alcohol and health Alcohols Distillation Flavors Alcohol chemistry

Usage

Compounds

Distillation

See also

References

External links