Continuous or pot, distillation is key

In my last column I talked about Eaux de Vie and how they were all distilled products. In fact every spirit is distilled, so let’s examine the process and you’ll have an idea how your favourite one is made.

Basically, distillation is the method of heating up a liquid until it becomes steam and then cooling again so it condenses back into a liquid. There are two main types of stills used for distillation: a continuous still and a pot still.

A continuous still, also known as a patent still or Coffey still acts just as the name implies: the process is continuous. Usually they consist of two tall columns with plates within. As the liquid is heated and turns into steam, it rises through one of the columns. All non-alcoholic liquids are burned and drawn off at the bottom, so by the time it reaches the top, the only thing left are alcoholic spirits in steam form. It is then cooled in the second column condensing the steam back into a liquid. This method of distillation is less expensive than the pot still version and the liquid that it produces is purer and more alcoholic, often up to 90 per cent by volume. The resulting spirit also doesn’t possess as much flavour or texture as that from a pot still. Spirits made this way include white spirits like gin, vodka, most rum, American whiskey, etc.

The pot still method of distillation is a batch method. The process is not continuous, so when the distillation process is complete, it’s done. Frequently, a pot still distillate is re-distilled. The still looks like a big copper pot with a long narrowing swan-like neck that leads into a condenser. It is usually heated directly by a flame. Because the process is not as pure as the continuous still method, the resulting spirit comes off the still at lower alcohol levels, around 60 – 80 per cent by volume. The real benefit of this form of distillation is the flavour and texture. Much more character and body are imparted to the final spirit. Spirits utilizing this process include Cognac, navy rum and single-malt Scotch. Pot stills can be very sensitive. The size of the pot and length of the swan-like neck can affect the flavour of the finished product. I’ve been told by single-malt Scotch producers that even the direction the pot still is facing or whether it’s angled at a doorway can affect the overall flavour.

In both methods, distilled water is added to the resulting distillate to bring alcohol levels down to what is required by law, around 40 – 45 per cent by volume. In countries or regions of origin, over proof products are often available. Occasionally there is some crossover between methods in that some continuous still products are distilled in a pot still for a specialty or unusual bottling.

All distillates are colourless, tasting of the ingredients they were made from, until oak treatment in a barrel or occasionally, in the case of some brandy, the addition of caramel. So what is the purpose of oak treating a spirit? Other than adding colour, it adds flavour, complexity and, most importantly, mellows the taste. Some spirits however simply don’t benefit from oak treatment. White spirits like vodka, gin and others would totally lose their character if oak aged. Others like brandy, whiskey, darker rums and scotch benefit greatly from it. The longer a spirit spends in oak, supposedly the mellower the tasting experience; however, there has always been a big debate as to the ideal length of time to age a specific spirit. Too much time may render a smoother attack on the palate, but may overwhelm the spirit with toasty, vanilla smoky notes, masking the true taste of the distillate. It’s simply a matter of taste though. Some people prefer a purer taste while others love the nuances extensive oak ageing provides.

Edward Finstein a.k.a. The Wine Doctor ­— wine writer, educator, judge, consultant

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