Fusel alcohol

Fusel alcohols, also sometimes called fusel oils, or potato oil in Europe, are a mixture of several alcohols (chiefly amyl alcohol) produced as a by-product of alcoholic fermentation.^[1] The word Fusel is German for "bad liquor".^[2]

Whether fusel alcohol contributes or not to hangover symptoms is a matter of scientific debate. A Japanese study in 2003 concluded, "The fusel oil in whiskey had no effect on the ethanol-induced emetic response" in Suncus murinus. Additionally, consumption of fusel oils with ethanol suppressed subjects' subsequent taste aversion to alcohol, which suggested subjects' hangover symptoms were lessened said the journal.^[3]

Contents

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• 1 Classification
  • 1.1 Hazardous alcohols
  • 1.2 Alcohol faults
  • 1.3 Aroma alcohols
• 2 See also
• 3 References
• 4 External links

Classification[edit]

Hazardous alcohols[edit]

• Methanol (methyl alcohol) itself, while poisonous (LD50 5628 mg/kg, oral, rat^[4]), has a much weaker sedative effect than ethanol.
• Isopropanol (isopropyl alcohol), oxidized to form acetone by alcohol dehydrogenase in the liver, has occasionally been abused by alcoholics, leading to a range of adverse health effects.^[5][6]

Alcohol faults[edit]

See also: wine fault

• Mannitol, a wine fault

Aroma alcohols[edit]

For desired alcohols other than ethanol in alcoholic beverages, seeAlternative_psychoactive_alcohol_use#Alcoholic_beverages_by_alcohol_type.

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, whisky (especially Bourbon), incompletely rectified vodka (e.g. Siwucha), and traditional ales and ciders, are expected to have relatively high concentrations of non-hazardous alcohols as part of their flavor profile. However, in other beverages, such as Korn, vodka, and lagers, the presence of other alcohols than ethanol is considered a fault.^[7]

The compounds involved are chiefly:^[8]

• 2-methyl-1-butanol - sometimes called "active" amyl alcohol
• isoamyl alcohol - also known as isopentyl alcohol
• isobutyl alcohol - one of the least toxic of the butanols.
• n-propyl alcohol

During distillation, 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. Freeze distillation, on the other hand, does not remove fusel alcohols.^{[citation needed]}

Fusel alcohols are formed when fermentation occurs:^{[citation needed]}

• at higher temperatures
• at lower pH
• when yeast activity is limited by low nitrogen content