How is Rum Made?

Sugarcane - the rum plant

Rum is made from sugarcane. Or more accurately, from molasses, which is a by-product of refining sugarcane into sugar. But let’s not get ahead of ourselves.

The hot and humid climate of South America creates the perfect conditions for sugarcane plantations. This is why the best rum is produced in countries such as Colombia, Jamaica, or the Caribbean Islands.

Sugarcane can take anywhere between 10 months and 2 years to grow. Once it matures, its fields are set on fire to remove pests and leaves, as it’s only the stalks that are used in the production of rum.

The stalks come out of the fire singed but largely unharmed - the high content of water protects them from serious damage in the flames.

Once the sugarcane is burnt, it must be collected as fast as possible and milled within 24 hours to retain its properties. The more time passes, the more sugar will be lost.

The harvest

Sugarcane can be harvested once or twice a year, depending on the region. This further contributes to the value of rum as the scale of its production is limited by the relatively low number of times sugarcane plantations can be exploited every year.

The stalks must be cut as close to the ground as possible, as the lower parts contain the most sugar. It used to be done by hand by workers called cutters. A skilled cutter could harvest up to 3 tons of sugarcane per day on average.

While this number sounds impressive, the introduction of machines called harvesters revolutionised the sugarcane industry. A harvester can collect as many as 146 tons of sugarcane in just 3.5 hours.

The vast discrepancy between the amount of sugarcane that can be harvested by humans versus machines led many industrial producers to switch to professional equipment. However, some smaller rum producers still largely rely on manpower.

Once harvested, sugarcane is washed, crushed, and then ground or pressed to produce sugar. This is where the real process begins.

Molasses

There are three main products of processing sugarcane: sugarcane juice, sugarcane syrup, and molasses.

Some kinds of rum are made from raw sugarcane juice. The liquid is the direct result of pressing sugarcane and extracting its juice. The rum produced following this method is called rhum agricole and is one of the rarest kinds of rum.

The rarest method of rum production uses sugarcane syrup. The liquid is made as a result of boiling raw sugarcane juice into a thick paste in order to refine it into sugar. Sugarcane syrup is a product in the stage between sugarcane juice and molasses.

The most common rum ingredient is molasses - around 95% of rum is made this way. Molasses is the byproduct of refining sugarcane - as the plant is made into sugar, a thick black paste forms and is cast aside by sugar producers.

Therefore, rum is essentially a product made of waste. First rum was produced as an experiment aiming to prevent large amounts of molasses from going to waste in sugar refineries. None of the initial inventors of rum dared to think the value it would have one day - serving as currency in the 18th century and an investment asset nowadays.

There are 3 different kinds of molasses:

• Unsuplhered - the best quality kind
• Sulphured - made from immature sugarcane
• Blackstrap

Another categorisation of molasses is according to its quality:

• Light
• Medium-dark - comes from the second boiling and is slightly bitter in taste
• Blackstrap - the product of the third boil containing between 55% and 65% of sugar

While some rum brands have their own sugarcane plantations and produce molasses on their own, others purchase them from sugar refineries. Paradoxically, the better the refinery, the worse the molasses it provides.

The best-quality molasses contains the most sugar. A good refinery is able to extract as much sugar from sugarcane as possible, providing molasses with a lower amount of it.

Fermentation

Fermentation is a crucial step in the production of rum as it is when rum starts developing its first aromas and flavour. The length of the process is anything from 24 hours to several weeks depending on the type of fermentation used in the rum-making process.

Fermentation is a complex chemical process which consists of several stages. First, molasses is diluted with water or - rarely - sugarcane juice. The quality of water matters, so some producers take care to filter it before it is used.

The mix of molasses and water turns into the so-called mash, which is then enriched with yeast. Yeast feeds on the sugar in the mash and produces alcohol and carbon dioxide. The initial product of fermentation is sugarcane wine containing between 8-10% alcohol.

There are 3 types of fermentation:

• Spontaneous/natural - This type of fermentation relies entirely on the yeast and other microorganisms present in the liquid. It usually takes place in open vats and lasts between one and two weeks. This is quite long for industry standards, so this method is mostly used by smaller distilleries.
• Controlled/batch - This type of fermentation is much quicker than the natural kind as it is enhanced by lab-grown yeast. It usually lasts between 2 and 3 days, making the process much more efficient.
• Continuous - This type of fermentation involves keeping the vat constantly filled by gradually adding more molasses throughout the process. This provides uninterrupted access to sugar for the yeast, which remains active.

Close getting closer - distillation

This is the part of the rum-making process where the spirit starts taking its shape. The aim of distillation is to separate alcohol from water and other compounds and ultimately increase the concentration of alcohol in the product.

There are two main distillation methods: distilling rum in pot stills (also called alembic stills) or column stills.

Pot/alembic still

This is the more traditional method, also used for the production of whiskey in Scotland and cognac in France. It involves stills resembling kettles in shape, which are usually made of copper. The use of this type of metal isn’t accidental - copper naturally removes sulphur which gives the product an undesired sour flavour.

Pot/alembic stills are the original and simpler type of stills when it comes to their build and functionality. However, simpler doesn’t mean worse. Many rum connoisseurs argue that rum produced in pot/alembic stills is more flavourful.

Distillation involving pot/alembic stills is generally used to produce heavy rum. The other distillation method involving column stills can be used to produce both heavier and lighter rum depending on when the rum is removed from the still. Pot/alembic still distillation doesn’t provide this choice.

Heavy rum is typical for former French and English colonies which include countries such as Barbados, the Virgin Islands, Guiana, and Martinique.

Alcohol evaporates at a lower temperature than water, traveling up the kettle-like still. The vapour then makes its way into the first of the two retorts attached to the main still: the low-wine retort. Low wine is the product of the initial distillation with an alcohol content of about 20%. The low-wine retort is filled with water-diluted low wines from previous distillations, which are boiled by the hot steam and directed into the second retort.

The second retort, called high-wine retort, is where the second distillation takes place. The product of this, called high wine, contains about 70+% alcohol.

The vapour with a high concentration of alcohol is then directed further into the heat exchanger, where it cools down and liquefies.

Column still

A column still is a more advanced version of pot stills. It is a series of lone alembic stills formed in a cylindrical tube which usually consists of two columns: the analysing column and the rectifying column.

The big advantage of this system is that a column still is able to distill liquid constantly without the need to stop. The end product is also said to be cleaner and more consistent and contain fewer impurities. Column stills can also produce rum with high alcohol concentrations.

However, this is countered by the fact that many rum enthusiasts find rum produced in column stills to be less flavourful than that made in single pot/alembic stills. On the other hand, some voices claim to find the taste of rum produced in column stills subtler and more refined, so it is likely a question of personal taste.

Column stills can produce both heavier and lighter rum. They provide the option to remove the product from the still before it becomes heavy - something that isn’t possible in the case of a single-pot still.

Light rums are typical for former Spanish colonies, including the Dominican Republic, Venezuela, Puerto Rico, and Cuba. Some rum brands combine light and heavy rum to create blends carrying the characteristics of both types.

The temperature in the analysing column changes from hotter to cooler, so the evaporating liquid progressively collects more alcohol. The vapour containing alcohol lifts higher, needing a lower temperature to boil than water, while the leftover water liquefies and drips down.

The purpose of the rectification column is to increase the alcohol content in the vapour even more.

Single-blended method

In fact, there is also a third method which combines pot and column stills. It is mostly used in the industrial-level production of rum as it produces large quantities of alcohol. It utilises five columns instead of two: wine column, extraction column, rectification column, demethylation column, and heads/tails concentration column.

The five columns work in a similar way as the two-column system, but the last column is worth mentioning. The final product of distillation can be divided into three categories:

• Head - the first toxic part that needs to be eliminated.
• Heart - the best part of the distilled liquid rich in ethyl alcohol and other favourable substances.
• Tail - the last part of the distillate which contains undesirable fatty and oily substances. Just like the head liquid, it needs to be removed.

A distiller’s true skill is measured by how well he or she is able to judge where the head part ends and the heart part begins and distinguish between heart and tail. You don’t want any good-quality distillate to go to waste, but at the same time, you can’t allow for the toxic or oily substances from the head or tail to make their way into the heart. Experts need to find the perfect balance between useful and waste.

Rum is always clear right after the distillation process, regardless of the method used. The ageing process is where it gains its colour.

Ageing

The ageing or maturation process is where rum gains its defining qualities such as aromas, tasting notes, and colour. Some rums aren’t aged at all, or only for a very short time.

Generally, the time spent in a cask influences the flavour and value of rum, which is why the longest-aged rum is the most expensive.

Rum is usually stored in oak barrels previously used to store bourbon. This is because there are strict rules regarding the production of bourbon - for whisky to gain the title of bourbon, a barrel can be used to store it only once.

Therefore, there is a surplus of ex-bourbon casks easily available to rum producers to be repurposed. However, some rum brands use casks previously used to store different kinds of alcohol.

For example, the Dictador 2 Masters Collection combines rums aged in casks from 11 different types of alcohol from the best producers in the world, including Port wine, whiskey, Champagne, Tokaji, and more.

Some rums spend the first few years in ex-Bourbon casks and are later transformed into other types of barrels. The sky is the limit for rum producers, and how they choose to age their rum depends entirely on what flavour profile they aim to achieve.

Forged in fire

Regardless of the barrels’ origin, they are always adapted according to a universal method. The wood is charred or toasted from the inside, depending on the degree. Toasted barrels are only slightly burnt and produce rum that is lighter in shade and sharper in taste. Charred barrels are burnt more severely and result in darker rum with a sweeter taste. They also filter out the harsher elements of the rum, making the end product smoother.

The burning process caramelises the sugar on the surface of the wood - this is why rum aged in charred barrels tends to be sweeter than that stored in casks that have only been slightly toasted.

The quality of the wood used in the casks’ production, as well as their treatment, matters in the rum-making process. The barrels are often re-used multiple times, and while old wood provides incredible tasting notes, a poorly treated cask can negatively influence the rum inside.

Another factor that impacts the quality of the rum is the location where the ageing process is carried out. Rum ages faster in hotter climates, which is why barrels are sometimes moved to colder countries in order to slow down the ageing process and allow the rum to soak in the flavour more thoroughly.

How long rum is left to age is entirely up to the producer. White rums are usually matured for up to 3 years or not at all, while rum needs to be aged for a minimum of 5 years to wear the badge “aged”.

However, many premium rum brands pride themselves on the long maturation period of their rum and aim to age it for longer. For example, Dictador has rum among its collections that has been aged for up to 60 years.

Some rum producers aren’t guided by the number of years as much as the desired flavour profile they aim to achieve. They mature the rum without any particular number in mind and carry out regular tasting to decide whether they’re satisfied with the spirit’s aroma just yet.

The pitfalls of rum ageing

There are certain traps rum producers need to watch out for when ageing rum. Perhaps the most significant of them is the so-called angel’s share, which is the amount of rum that steadily evaporates during the maturation process.

The rate at which rum evaporates is higher in hotter climates - up to 5-7% of volume is lost every year. This is another reason why rum casks are sometimes moved to cooler countries where the annual angel’s share drops to 2-3%. The rum lost as a cause of evaporation is usually replaced with rum from other casks which started their ageing process at the same time.

Another reason why barrels are transported is the method called dynamic ageing. For some rum producers, placing casks on a ship has more importance than their target destination. The movement of the ship on waves allows for the liquid inside the barrels to move around, making a higher percentage of the rum come in contact with the charred walls. This does wonders for the flavour profile of the final product.

The Solera method

Some rum producers use the Solera method, which originates in Spanish winemaking. Older casks are usually stacked at the bottom with younger rums stacked upon them. According to the Solera method, a portion of rum from the bottom casks is blended with the younger rum from the top to create new flavours.

However, there is some controversy surrounding this particular method. It has to do with the inconsistencies of the age of the rum that is put on the bottle, which result from mixing younger rums with older ones.

Generally, the older the rum, the higher its price, so some say the Solera method manipulates the value of rum and deceives customers. Producers using this method in their rum production should state which percentage of the liquid actually has the age they claim on the bottle’s label.

This is why you may sometimes encounter 30-year-old rum with a tiny disclaimer at the bottom saying that in reality only 4% of rum in this bottle is 30 years old, with the majority being much younger.

Charcoal filtration

Some guides explaining how rum is made leave this stage out, but we didn’t want to omit it as it constitutes a crucial part of the production of light rum.

Charcoal filtration can take place either before or after the ageing process. If it happens after the maturation, aged rum will lose its colour. This is why the quality of rum shouldn’t be judged by its colour - white rum is usually aged for a few months or years, or not at all, but even aged rum can become colourless if it is subjected to filtration.

The role of the charcoal filtration process is to remove any harsh and undesirable elements from rum and gain a smooth final product. Different types of charcoal target different substances, so the kinds used depend on what the producer wants to eliminate.

Blending

Blending is a combination of science and art. The process consists of blending rum from different vintages and distillation methods to create unique flavour profiles.

The person responsible for blending is called Master Blender - they must know everything about the rums they have available and be able to predict how they will react when mixed together. They also have to select the right proportions and combinations to reach the desired effect.

Sometimes the newly blended rum can be subjected to further ageing to reach a completely different flavour profile. Before rum moves on to the final stage of the rum-making process, which is bottling, it is left in tanks to allow the new blends to mix.

There is a certain controversy regarding adding certain substances to rum during the blending process. Caramel is a common component used to enrich the flavour and colour of rum.

Legislature fails to regulate the laws regarding the substances and their amount which is allowed to be added to rum in certain countries. The same applies to age statements on bottles, which is the reason for the discussion around the Solera method.

Bottling

Blended and aged rum is ready for bottling and distribution. Although rum gains value primarily due to the amount of time it spends in casks, its price often continues to increase even once it is bottled.

Many premium rum brands release a limited number of bottles from each vintage or collection, creating a sense of exclusivity. Often, not everyone who would like to purchase a specific bottle of rum is able to, creating a demand for them on the secondary market.

These are all the stages of rum production - the complexity of the process and the time it takes for rum to go from a sugarcane seed to inside a bottle explains the true value of the spirit. We hope that the awareness of how rum is made will make you appreciate the liquid gold even more, knowing how many people, expertise, and years are involved in delivering a bottle of rum into your hands.