ORIGINS: RUM - PART 2 - CULTIVATION, EXTRACTION, FERMENTATION & DISTILLATION
Now for part two in our Origins series - the process. We take a closer look into how our liquid, and rum in general, is made from sugar cane to glass. In this particular edition, we’ll look at the cultivation, extraction, fermentation, and distillation processes of rum.
While part 1 all started with sugar cane, so does part 2. Whether it’s sugarcane juice or molasses - all rum is produced from a sugarcane byproduct.
And the region it’s grown in impacts the plant and the profile of the rum it produces - there are many different types of sugar cane - and also why each nation’s rum has its own quirks.
Rhum Agricole vs Rhum Traditional
Throughout the French islands sugar cane juice is predominantly used and often produces ‘rhum agricole’ which tends to have a grassier profile than traditional rum.
However, the vast majority of rums are made from using molasses - like all of the rums in our blend - and are known as ‘rhum traditional’. Molasses is a dark, sweet, thick syrup and results from the extraction of sugars from sugar canes.
At sugar mills, sugar cane is chopped and crushed to extract the juice. This is then boiled to reduce water content to leave a syrup called ‘wet sugar’. This is then clarified and combined with sugar crystals before being boiled, cooled, and then spun in a centrifuge to separate the crystals from the liquid.
That process is repeated a couple of times and produces sugar - as you’ll find on supermarket shelves. What’s left behind is molasses.
Fermentation and Distillation
Whatever sugar cane derivative ingredients are used this is then fermented with water and yeast to produce a beer like wash of 5-10% alc/vol.. This is then distilled to make rum.
Distillation follows the principle that alcohol boils at a lower temperature (78.3°C/165°F) than water (100°C/212°F). Therefore if you take a mixture of alcohol and water, boil it, collect the vapours given off in batches throughout the boil, cool and so condense the vapours back into the liquid, the liquid collected at the start of the boil will be alcoholic and those towards the end will be water. Sounds relatively straightforward…
In reality though the process is quite a bit more complex and there are many factors which can affect the final distillate produced. We’ll keep things relatively simple though. One of the things which definitely affects the distillate though is the still in which it’s produced in - either a pot still or column still.
Pot stills are the most simple and original type of still - essentially they are fancy copper kettles and are used in Scotland to make malt whisky and in France to make cognac.
The still is charged with the wash and then is brought to the boil. The volatile ‘high wines’ or ‘heads’ are produced first and set aside, partly due to being tainted as they effectively clean the still from the previous distillation.
Then comes the desirable part of the run known as ‘the cut’ as the alcohol level of the distillate collected starts to fall, and the ‘low wines’ or ‘tails’ arrive and are set aside.
It’s common for pot still rums - just like as in Cognac and Scotland - to be double distilled. The distillate collected from the first distillation with an alcohol strength in the low twenties and the second distillation typically over 70%.
Column stills meanwhile can be run continuously without the need for stop and start between batches like with pot stills. This along with the higher concentration of alcohol in the final distillate makes column stills much more economical to operate than pot stills. They also allow the production of lighter, cleaner rums than the heavier rums produced from pot stills.
Regular column stills consist of two tall columns, an ‘analyser column’ and the ‘rectifying column’. Perforated copper plates sit horizontally in each. Steam is introduced at the bottom and the wash mid way up. The hot steam rises through the still with each plate acting to distil the wash with heavier compounds unable to rise to the next floor.
Both columns are linked, the second further purifying the vapours from the first while heating the wash that will charge the first column. The taller the stills, the more plates they contain and the purer the alcohol will be that’s produced.
Once condensed, we have our distillate and we have rum. White rum is often just sugar cane distillate watered down and bottled but most rums are aged. We’ll take a look at that in part 3 of our series.