Whether fusel alcohol contributes to hangover 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 response" in the Asian house shrew. Additionally, consumption of fusel oils with ethanol suppressed subjects' subsequent taste aversion to alcohol, which suggested subjects' hangover symptoms were lessened, according to the journal.[3]
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 alcohols other than ethanol is considered a fault.[5][failed verification]
The compounds involved are chiefly the following:[6]
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. On the other hand, freeze distillation does not remove fusel alcohols.[citation needed]
Fusel alcohols can be reduced during fermentation by lowering the fermenter's temperature or increasing the oxygen content.[7]
^"Fusel oil". Oxford Dictionaries. Archived from the original on 2013-01-26. Retrieved 2013-01-21. - Blazquez, Rodrigo. "Higher Alcohols". Waterhouse Lab. UC Davis. Retrieved 22 September 2020.
