Rum Production

Sugarcane field

Rum is produced from either sugar cane juice or from the sweet, sticky residue left over when sugarcane is crushed and the juices heated, the heating causes the juices to solidify into sugar leaving this residue called the molasses.


The molasses are then mixed with water and re-boiled to produce a sweet liquid called the mash which is then mixed yeast and left to ferment.

The molasses will contain around 30-40% sugar; molasses with higher amounts of sugar will produce more rum. Nowadays, sugar production is so advanced that many rum producers have difficulty obtaining molasses with enough sugar.



The fermentation time depends on the style of the rum; light rums are fermented for around 24 hours whereas dark rums can be fermented for up to 3 weeks.


The yeast is very important in the production of rum and most producers have identified a strain of yeast that best suits their style of rum. The yeast is cultured to allow a never- ending supply.

A small amount of yeast is often mixed with a small amount of the mash to begin the fermentation, this is then added to the remaining mash in the fermentation vats.


The way the yeast acts with the molasses and the length of time the fermentation lasts will greatly influence the style of the rum.


The shorter the fermentation the lighter the rum and the longer the fermentation the more full bodied the rum. This is due to the build up of impurities in the fermentation process.

Some rum makers will use a system of continuous fermentation, as this is a more efficient and less expensive method of rum production.

The fermented liquid is called the wash



The style of the rum also dictates the distillation process, light rums are highly rectified in continuous stills and are often filtered through activated (hot) charcoal to remove the impurities.


These are known as single distillates and will usually be blended with other rums.

Gold (añejo) and dark rums are usually distilled in pot stills.


Distilling in a pot still is generally done twice as this increases the alcoholic strength and also removes more unwanted impurities. Pot distilled rums are fuller bodied with a rich flavour that continuous distilled rums. As with light rums, pot distilled rums will usually be blended.



Oak BarrelsThis ageing is done in oak casks, usually ex bourbon barrels imported from the USA, although other barrels such as ex-cognac may be used.


The casks are re-charred as the charring will mask the flavour of the whiskey, neutralise some of the off odours from the rum and to add the flavour components when the rum is added.

Ageing in charred oak adds flavours such as vanilla, spices, fruits and wood. Ageing in wood also gives the naturally clear spirit its colour due to the tannins; in most cases caramel is added to the spirit to deepen the colour and sometimes to increase the sweetness.


Supposedly, rum was originally sold straight from the still, however the unsold rum was stored in oak barrels and it was soon realised that the rums character began to change and greatly improved the spirit.


Many dark types of rum attain their deep colour not from long ageing but from the addition of caramel or molasses syrup.

When the rum is aged, the alcohol evaporates through the pores of the oak and air is absorbed into the rum. The air oxidises the alcohol and turns into aldehydes, which then turn to acids and then turn into esters (fruity aromas) the longer the rum ages for. Esters (fruity aromas) are good sign of how long a product has been aged for.

When the rum is ageing, a certain amount will be lost through evaporation this is called the ‘duppy’s share’ (ghosts share). Because the climate in the Caribbean is very warm this rate of evaporation is very high, the rate of maturation is around three times faster than in Europe.

Every rum producing country will have differing amounts of rum that are lost to evaporation. Each countries government will set guidelines allowing for this evaporation as each barrel of rum is taxable so if the evaporation is over the guidelines there will be tax to pay.

Although not required to age, most rum producers will mature their spirit as it helps the rum settle and become smoother.

Light rums can be aged and are then filtered through charcoal to remove the impurities and to further mellow the spirit. Charcoal filtering rum was developed by the Bacardi Company.

Gold and dark rums are aged between three and twenty plus years.



Virtually all rums are produced from blends.

Blending is the way rum producers develop their own unique brands and it also allows them to produce each brand consistently.

The art of the blender is too produce a consistent product using either rums of the same ages but different barrels when blending light rums or from rums of differing ages, especially when blending aged rums.

Most producers will blend a mixture of rums from continuous still and rums from pot stills to create their brands; the rum from the continuous will be light in flavour but will contain vanilla and oak flavours and the rum from the pot still will provide the body, the esters and other flavour components.

The blender will also use rums from the continuous still that will have differing levels of rectification (purification); these will be aged in barrels and used in the blend.