June 24, 2009

Aeneas Coffey and the Column Still

Aeneas Coffey was an Irishman who was born in France in 1780. Somewhat ironically, Coffey was an excise officer, and made a living investigating and shutting down illegal distilling operations. Perhaps his familiarity with whiskey production was the impetus behind his patenting of the Coffey still in 1831.

The Coffey still, a.k.a. the continuous still, the beer still, the column still, and the patent still, is the device that intially seperates the alcohol from the mash, discussed here. Coffey's still, which was really a revamp of an existing still designed by the Scotsman Robert Stein, inlcuded two columns, one named the analyzer and one named the rectifier. The analyzer essentially heated the cold mash that was pumped into it, almost to the point of boiling. The now-heated mash was then sent over to the rectifier. The rectifier is basically what has become the column still in virtually all of American whiskey distilleries (Woodford Reserve uses old alembic-style pot stills) and is where steam meets the mash and vaporizes the alcohol from everything else. Modernly, the need for the analyzer has fallen by the wayside.

The column still has several advantages of its pot still predecessors: it can be used continuously instead of emptied, cleaned, and refilled after every use like pot stills; it can produce much greater quantities of alcohol faster than a pot still; it is cheaper and more efficient to operate; and produces purer, higher concentrations of alcohol. These advantages made the column still ideal in the US for post-Civil War distillation, when distilleries began to turn their plants into large-scale production centers and efficiency was key. They remain a vital part of bourbon production today.

The column still has not overtaken the whiskey industry. Scotland refuses to use them, because they believe that their traditional pot stills produce higher quality results. To an extent, this is true, with the caveat that "higher quality" is a subjective term - since pot stills yield less concentrated alcohol, there necessarily remains more impurities in the liquid (the higher the alcohol content, the less room for impurities, such as cogeners and proteins), and it is these impurities that influence the whiskey's flavor. So, the argument goes, column stills strip away too many flavor-enhancing impurities compared to the alembic/pot stills. I will now happily end this post without opening any doors to a bourbon vs. Scotch debate.

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