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hen attempting to differentiate distillates, producers and brand owners often refer to the equipment they own and operate as if the mere mention of the distillation apparatus could quantify the quality of the resulting spirit. This approach is the equivalent of suggesting that the brand of car a person owns dictates the manner in which that person drives. Authentic craft distillers will be quick to suggest that their spirits are distilled using pot stills, criticizing the “industrial” and “mass production” spirits from continuous distillation columns as being the archenemy of flavor and quality. By the same token, large distillers will use continuous distillation columns because they allow for consistent, around the clock, cost-effective production of alcohol. So far both camps have their advantages and disadvantages, so what about quality? Quality is all about congener diversity and quantity. Let me elaborate: Congeners are formed during fermentation, hence their name, which in Latin means “similar” or “related” but can also mean “born at the same time.” Pot stills and column stills differ in how those congeners are concentrated and separated. To say that only pot stills can produce heavy alcohol and that continuous columns can only produce light alcohol is as erroneous as suggesting that a minivan can’t go over 70 miles per hour or that a sports car can’t drive through a school zone without putting children’s lives at risk. The biggest source of confusion stems from the fact that a lot of the literature about distillation fails to treat congeners with granularity, lumping them together as WWW.ARTISANSPIRITMAG.COM
PHOTO COURTESY OF RUM RUNNER PRESS, INC.
produce an agricole-style rum (“rhum”), one should select a yeast that produces a high quantity of congeners. A “heavy” rum can be defined as one But even a yeast that is perfectly suited having at least 250 mg of congeners per for vodka production (low congener) can 100 ml of AA (absolute alcohol, or alcohol produce a large quantity of higher alcohols, at 200-Proof). We could have a rum that especially amyl alcohol (pentanol) if it lacks meets this criteria, where most of the certain key nutrients during fermentation. congeners are in the heads (light aldehydes In the world of rum, for example, it is known and light esters), resulting in something that a lack of Nitrogen during fermentation quite fruity and mixable. We could also have will result in higher production of fusel a rum where most of the congeners are in oils. In the old days, people would add the tails (heavy alcohols, heavy aldehydes urea (CH4N2O) as a source of Nitrogen, and heavy esters), resulting in something until it was discovered that doing so oily, diesel-like, mostly unpleasant. would result in the production of ethyl Why such variation in results? Aren’t all carbamate, which is a known carcinogen. congeners the same? The answer to this Rum distillers today use other salts as a last question, as you may have guessed, is source of Nitrogen, such as Diammonium no, they are not all the same. Phosphate ((NH4)2HPO4). To understand why, we must first take Ethanol is, by volume, the most abundant a couple of steps back and look at the alcohol formed during the fermentation of chemistry of alcohols and at the metabolic potable alcoholic beverages. Other alcohols pathways leading to their initial creation. include methanol, butanol, propanol and pentanol. Each of these alcohols can, The goal of fermentation is to produce through oxidation, produce a different as much usable alcohol as possible. aldehyde. Each aldehyde, in turn, oxidizes The goal of distillation is to concentrate into a different acid and finally, each acid ETHYL ACETATE that alcohol while separating it into its (C H O2) 4 8reacts with each alcohol in the distillate to desirable and non-desirable components. produce a different ester. Yeasts are selected (or should be) In a distillate that is 100% pure ethanol based on how efficiently they can get the (C2H6O), the only aldehyde we’ll obtain ETHANOL ACETALDEHYDE ACETIC ACID job done, given the and (C H O) (C2environmental H6O) (C2H4O2) is acetaldehyde its oxidation 2 4 through physical conditions at the distillery. (C2H4O), which in turn oxidizes into When the goal is to produce vodka, acetic acid (C2H4O2) which, when for example, one should select reacting with the starting ETHYL ACETATE a yeast that creates a low (C4H8O2) ethanol gives us the quantity of congeners. ester ethyl acetate By the same token, (C4H8O2). when the ETHANOL ACETALDEHYDE ACETIC ACID goal is to an “all or nothing” proposition. Here is an example:
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(C2H6O)
ETHYL FORMATE (C3H6O2)
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(C2H4O)
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(C2H4O2)
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METHYL ACETATE (C3H6O2)