#boozetree

Oddly enough, yes they do (in an very specific branch of the culinary world)!  Fusel alcohols play a role in the distillation of spirits, a huge class of alcoholic beverages made from fermented drinks (such as beer and wine).

Ethanol, which we usually call the alcohol in cooking, is very simple chemically.  The drinks its found in, however, are chemical cocktails of the highest order.  Here’s how it breaks down:

The source of sugar in fermented alcohol determines what major branch of the booze tree it belongs to.  If the source is a starch, such as a cereal grain, we call it beer.  If it’s fruit, we call it wine or cider.  Honey gives mead, rice gives sake and the whole subtree of rice alcohols.  And it doesn’t stop there; even mare’s milk can be fermented into booze.

Fermentation is an extremely simple process on the surface, but like everything with alcohol, it only looks simple.  It’s probably better suited for it’s own post, but the short version is this: Yeast convert sugar into carbon dioxide, ethanol, and the dazzling array of byproducts that gives each class of fermented beverage their unique character.

Even wine can spoil, though, so distillation was invented to draw out the essence or spirit of the beverage and refine it.  Distillation is a difficult process by which a solution of beer or wine is boiled to the gaseous phase.  Since water freezes and boils out as a pure substance, the resulting vapor is called distilled water.  This process also takes advantage of the extreme volatility of the compounds already in the starting liquid.  Alcohol and most of the desirable compounds are airborne earlier than the rotgut or fusel alcohols/oils that come after.  (Fusel even means “rotgut” in German.)

For the more chemically minded of you:

Most distillation processes call for dumping the first run, or moonshine.  However, just the slightest hint of the higher order or longer alcohols can give, say, a Scotch a part of its character than the charcoal barrel in which it matures cannot.  Anymore than the slightest hint, though, and the booze turns oily and down right nasty.  Vodka, which in the USA has the legal definition of an odorless, tasteless, and colorless solution of water and at least 30% alcohol by volume, omits most (if not all) of these fusel alcohols thanks to being distilled and re-distilled anywhere from 4 to 5 times and is even scrubbed by some of the same activated charcoal found in water filters.

For this post,  my thanks once again to Harold McGee’s On Food and Cooking, and my old food chemistry professor Dr. Brady.  You’ll be hearing a lot of their wisdom on this tumblr!