Distilling it down

How do we get the high-proof rum we love so much? Well, you must start with fermentation, a process that happens pretty much on its own with fresh sugarcane juice or diluted molasses.

A controlled fermentation process with yeast can quickly create an alcoholic beverage of reasonable strength. But if you want to get to spirit strength, you need to distil the wine, and that is a process that relies on the rather convenient fact that alcohol – more specifically ethanol – has a boiling point that is lower than that of water. By carefully heating your wine, you can collect the alcoholic vapour and condense it back to a liquid.

The oldest method of distillation is to use a pot still, producing alcohol in batches, separating the undesirable components in the form of the heads and tails – keeping only the heart. The earliest designs were little more than a clay pot with a water-cooled lid incorporating a cunning way of collecting the condensed vapour. Modern copper pot stills offer far more control over the process with increased rectification and an alcoholic spirit around 85% ABV. However, it remains an artisanal batch process, capable of making characterful spirits of different specifications.

The notion of continuous distillation requires a far more efficient solution than the pot still, and it is fair to say that the design patented by Aeneas Coffey was an elegant refinement of the work of others. The genius of the fractional distillation design is that if the system remains stable in terms of inputs, outputs and temperature, you can continuously collect the desired alcohol. Highly efficient systems can produce spirit up to 96% ABV; however, this is highly rectified and tends to be light, virtually neutral, in character.

Understanding the characteristics of distillation styles and using the Gargano Classification will take you a long way to a deeper understanding of rum.