In a previous article: Christopher Columbus and Sugar Cane, I mentioned how he transported sugar cane seedlings to the Caribbean. However, from that point there is still a long way to go before you get to the bottle of rum that is (hopefully) sitting in front of you.
The bulk of all sugar cane is still harvested by hand throughout the world. It is cut down by machete and then transported to machines which crush the sugar cane’s hard stalk. This extracts sugar cane juice. From here depending on the producer of rum we have three different options.
1) If producing Rhum Agricole then the fresh juice is moved directly to the fermentation and distillation process.
2) This juice can be cooked and concentrated into sugar syrup and then fermented and distilled from here.
3) The fresh juice is then manipulated into molasses and crystallised sugar. The molasses are sold to distilleries and are fermented and distilled into the bulk of rums that are produced today. They also contain a noteworthy amount of minerals and other elements which contribute to the flavour of the final product.
From any of these stages, we end up with the raw materials for the next stage in production cycle, which is fermentation.
Please visit Part 1 here if you haven’t already, about sugar cane.
Now we have the raw materials we can move onto the fermentation stage of production. It is from this point where huge amount of variation occur from distillery to distillery. The two extremes of the fermentation process vary from “natural fermentation” to laboratory conditions. Natural fermentation occurs in large open vats where the yeast in the environment ferments the sugars. It can be quite inefficient and unpredictable. Laboratory conditions include specific yeast cultures which are purchased by distilleries as well as precautions to minimise environmental affects.
The addition of this yeast (and to a lesser extent, water) is what converts the available sucrose into alcohol. The time is takes can last from just a few hours to a few weeks and also depends on the yeast that is added to the raw materials in this process. Once this has been completed and there is almost no sugar left, the distillation process can begin.
Please click here for Part 1 about sugar cane and Part 2 about the fermentation stage.
Now that we have fermented the raw materials, we can move on to distillation stage. The fermented liquid is placed in a still. During early stages of rum production, these were pot stills, but as technology has advanced these are now almost universally column stills. From here the still is heated to around 80 degrees C which is where alcohol boils and then evaporates. The steam created from this evaporation is then collected and re-condensed. When re-condensed, this liquid will be between 40-98% alcohol depending on the environmental factors in which it was created. This could be bottled and sold as rum if desired by the manufacturer. At this stage the rum will be colourless and clear and is quite raw.
It would be easy to say that this procedure seems quite basic and simple. However, there are a variety of different factors which go into this science of the distillation. The shape and size of the stills (which are hand made) all add to the final product. The stills could be very complex or remarkably simple. Also at this stage, some distillers may choose to remove certain chemical elements. We now have raw rum which could be bottled. But in most instances we now move onto our next stage in the production cycle which is aging.
The first three stages of production can be found here: part 1, part 2 and part 3.
Now we have our rum, we move onto the aging process. This is done to help remove the harsh taste acquired from small amounts of hydrogen sulphide gas which is created during the fermentation process. Due to the high cost of barrels and the relative low cost of rum when it was first aged, rum has almost always and still till today, uses oak barrels which once were used to age whiskey or bourbon. These barrels not only add flavour to the rum but also colour. If the rum is aged in stainless steel tanks it will stay mostly clear. The minimum term rum will usually be aged for is one year.
Rum can be aged for decades if desired but depending on the process we get a loss of rum known as the angel or ‘duppy’ share. The higher the share, the less rum remains after the aging process. The highest angel share I have come across was quite recently where it was over 75% of the rum in the Velier Uitvlugt ULR 1997 (Review here). The final part is next and is the blending and bottling of the rum.
The earlier four parts can be found here: Part 1, Part 2, Part 3 and Part 4.
Now we have aged the rum, the distilleries almost always decide to blend the rum with other batches some of which maybe aged for different periods of time. Spiced rums can also be infused with herbs, fruits and spices to produce flavoured rum. Also it maybe diluted with water to help bring the alcohol level down to 40-50%. Once the colour, taste, consistency and anything else the master blender wants to manipulate has been done, the final product is ready to be bottled and distributed. The entire process can be completed in weeks if you do not require your rum to be aged.
As you can see there are only between 3-5 steps for producing rum depending on how you want your final product. However, the endless possibilities in the variety of stages make rum an extremely unique product with endless flavour profiles!