If you've ever been curious about how your favourite spirits are made, you may have come across the term "bubble plates." But what exactly are they and how do they work?
Bubble plates are a key component of a distillation column, which is used to separate and purify the different components of a wash or mash. Originally introduced in 1828 by Belgian distiller Jean-Baptiste Cellier-Blumenthal bubble plates feature a number of "caps" that allow alcohol vapour to pass up the column, as well as a "downcomer" that lets excess liquid on the plate fall back to the plate below.
This rising and falling action helps to separate the different types of alcohol in the still, with lighter alcohols gradually moving upwards where they can be removed so that they don't form part of the final product. The heavier alcohols, on the other hand, remain lower in the column and are eventually removed once the unwanted alcohols that form the foreshots, and heads are removed.
One of the main benefits of using bubble plates in a distillation column is that they allow for greater control over the distillation process. The distiller can adjust the height of the plates to control the reflux ratio, this is the amount of vapour that is condensed and returned to the column. This helps to regulate the rate that good spirit is collected and can help to produce a more consistent, high-quality spirit.
But bubble plates aren't just about control – they also play a key role in producing a clean, delicious, and neutral alcohol. Having a high level of copper contact helps neutralise and remove flavour and aroma compounds that aren't desirable in the finished product, and by forcing the alcohol vapour to pass through the bubble plates multiple times this effect is greatly enhanced.
Of course not all spirits require high reflux. It's mainly used when producing neutral alcohol, either for use as vodka or to form the base for other products. Whisky, brandy and other aromatic spirits are produced using virtually no reflux in order to capture the flavours of the ingredients.
So there you have it, bubble plates are a critical component of a distillation column, allowing distillers to control the reflux ratio, separate out impurities, and produce a high-quality, neutral alcohol. Whether you're a seasoned distiller or simply curious about the process, understanding the role of bubble plates can give you a greater appreciation for the art and science of spirit-making. So, the next time you raise a glass of your favourite spirit, remember to give a nod to the bubble plates that helped make it possible. Cheers!