RUM – WSET Spirits Unit 4 Preparation


Known in past times as ‘kill devil spirit’ or as ‘rumbullion,’ no other spirit has as many types or ‘marks’. It can be light, golden, spiced, dark, old vatted, navy, or vintage, made from a mixture of molasses and water or from fermented sugar cane juice and from countries as widely flung as Australia, Philippines, Jamaica, Guyana, Brazil and India.

Neither has any other spirit had the ‘hideous waltz’ (Dave Broom, ‘Rum’) that rum has had with slavery, sugar and rum. Some cities were literally built on this triangle including Nantes and Bordeaux, Liverpool, and Newport, Rhode Island. The trade of African slaves sold to Caribbean plantations to produce sugar that was sold in Europe and America – and then rum as well which was subsequently used to buy more slaves – went on for over a hundred years. A middle class drink in London and Europe during the 1800s, few truly realized the true extent upon which their enjoyment of the spirit was built upon the misery and destroyed lives of so many.

Most rum is made from molasses and to get molasses, one needs sugar cane. It is possible to have 1 (February to June) or 2 harvests a year (further to the tropical south) and the cane typically grows to 10-12 feet tall and when harvested (by hand or machine) it yields 12-14% sucrose. Most plantations will grow several species incase of disease. It must be transported as soon as possible to the processing mill (as the Jamaicans say, ‘from kill to mill in 24’) so that the sugars don’t deteriorate too much.

At the mill it is chopped, crushed and pressed and the sugar cane juice is collected. It’s boiled into a syrup, clarified and boiled again and then centrifuged. The sugar crystals are picked out and eventually the gooey, black residue left is what we know as molasses.

Because today’s processing mills are so adept at getting most of the sugar out of the sugar cane it’s actually becoming problematic for rum producers because the molasses used in rum production must have at least 52% sugar in it. It’s becoming increasingly difficult to find that high a level of sugar in molasses. To make matters worse, many major rum producing countries even have to resort to importing molasses (ie: Jamaica and Barbados) from Guyana, Brazil or Venezuela.

This means it’s more expensive to produce because it’s harder to extract sugar from each ton of molasses. Generally speaking one requires 2.5 kgs of molasses to make 1 litre of rum at 57% abv.

The next step is fermentation but because molasses is so sweet and the yeast would die too quickly, it is diluted with water prior to adding the yeast (about 10%). The level of dilution affects the type of ‘mark’ of rum that will be produced. Wray & Nephew (Appleton Estate, Jamaica) produces several different marks so they can blend them together.

Yeast is very important to rum producers – it attacks the sugars and produces CO2 and alcohol. Most producers will either swear by their own special brand of yeast (Bacardi’s is kept under lock and key) or buy a commercial brand (that they’re sure will produce exactly the type of rum they want). A very few artisanal producers still use ambient yeast (ie: Callwood Estate, Virgin Islands). The reason yeast is so important for flavour is that it doesn’t only produce alcohol, but also butanol, propanol and methanol (which no one wants in a spirit!) and also the precursors of aromas and congeners.

Fermentation is important because not only does yeast affect the flavours and aromas of each mark, but the length of the fermentation does as well. For example, the length of the ferment affects the concentration of acids and aldehydes (esters – ‘high’ aromas). So, the longer the ferment, the more deeply concentrated the acidity and concentration of the aromas.

Jamaican rums take fermentation to an art form – at Wray & Nephew, their ferments can last from as few as 30 hours to over a week! Even Dunder and sugar cane millings may be added to the very long ferments to increase acidity (Dunder is the acidic mess/spent lees left in the pot after the first distillation, fermented further in Dunder pits in the heat and added into the retorts during distillation – in Bourbon production, they’re called backset and used for sour mashing).

In Jamaica, rums are classified according to their esters (organic or volatile compounds produced during fermentation); a Common Cleans has about 80-150 esters, Plummers 150-200, Wedderburns 200 or more and Continental Flavoured 500-1700. The style is directly connected to the length of the fermentation. So, a Plummers may have been fermented for 2 days, a Wedderburns 3-4 and a Continentals as many as 5-10! Controlling heat is often a problem with the fermentation as it’s the tropics after all! Some producers cool their fermentation tanks and others control the fermentation by dripping in the molasses to the tanks over time so as not to overwhelm the yeast.

Traditionally rum was distilled in pot stills, made in small batches with an alcoholic wash of about 7% (so 93% water). Today some still are, but many of the lighter marks are made in multiple column continuous linked stills (ie: Bacardi’s iconic Superior is distilled in a 5 story tall one).

As alcohol boils at a lower temperature than water, the theory is that the alcohol vapours will evaporate and travel across the lyne arm to the condenser where they’ll be collected as spirit after cooling. The first time the spirit is only 23% abv, so it must be done another time to reach about 72% abv. The heart is separated from the low and high wines and retorts (closed copper vessels that concentrate the spirit further) are used as well. Retorts contain the low and high wines from the previous distillation and concentrate the spirit even further.

The talents of the distiller are of vital importance at this point as only he/she will know the proper cut points at which to separate the high wines, heart and low wines at. The heart will be collected from the retorts and the still at 85% and the low and high wines recycled back into the next batch’s retorts. Each country has a specific style – Jamaican rums are high ester and Guyanese rums tend to be weightier and less pungent (from the Diamond Distillery Ltd with its historic and one-of-a-kind Greenheart Wood pot stills).

The rum run usually follows high wines notes of flowers, apple and unripe banana, followed by the heart which is tropical fruit. The low wines are progressively heavier and the fusel oils appear after leathery and oily notes, followed by some rank and unpleasant ones.

About winellama

I love wine...and finally decided to do something about it.
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