Talk:Freeze distillation

Okay, what fermentation products are unhealthy that are concentrated by this process? -- ~ender 2005-02-26 10:13:MST

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(From the wiki article "Fusel alcohols")

Fusel alcohols, also sometimes called fusel oils, are higher order (more than two carbons) alcohols formed by fermentation and present in cider, mead, beer, wine, and spirits to varying degrees.

The compounds involved are chiefly:

* 1-propanol * 2-propanol * butanol (various isomers) * amyl alcohol * furfural

Excessive concentrations of these fractions can cause off flavours, sometimes described as "spicy," "hot," or "solvent-like." Some beverages, such as whiskey, Siwucha and traditional ales and ciders, are expected to have relatively high concentrations of fusel alcohols as part of the flavor profile. In other beverages, such as vodka and lagers, notable presence of fusel alcohols is considered a fault. Very high concentrations — usually caused by incompetent distillation — can cause acute illness, including headaches, nausea, vomiting, clinical depression, or coma. Such a liquor may be referred to as rot-gut or rotgut.

Fusel alcohols are formed when fermentation occurs:

* at higher temperatures, * at lower pH, * when yeast activity is limited by low nitrogen content.


 * Thank you anonymous hero.
 * However, I'd still like to know how much fusel alcohol (by percentage?) is considered dangerous, how you might test for such a thing and/or prevent it. I see low temperatures and high pH would be desired, according to your post - but that makes me confused when the article says that freeze distallation would cause a too-high concentration of such products...
 * ~ender 2005-10-03 16:09:MST


 * It says that fermentation at high temperatures produces more fusel alcohol, but freeze distillation is distillation, and in distillation low temperatures leave more fusel alcohol in (apparently). NHammen 16:13, 7 August 2006 (UTC)


 * freeze "distillation" is not distillation, thats why there are fusels in the product. fusels boil at higher temperatures in true distillation, so are easily seperated. Xcomradex 04:05, 7 September 2006 (UTC)

I suspect that in many cases the more immediate concern is concentration of methanol. (Excessive methanol in bootleg liquor is a well-known problem.) RomanSpa 00:49, 28 September 2006 (UTC) 
 * Wouldn't the frozen material become progressively poorer in alcohol content?

"The liquid left behind would be richer in alcohol, and as a consequence, further freezing would take place at progressively lower temperatures, and the frozen material, while always poorer in alcohol than the (increasingly rich) liquid, would become progressively richer in alcohol." 138.162.0.44 05:21, 12 July 2007 (UTC)