All rums are made from sugar cane.
Agricultural rum is obtained by the direct fermentation of sugarcane juice or “vesou”, without prior extraction of the sugar contained in the cane, then by distillation in a still or in a distillation column.
Traditional rum, or molasses rum, is a byproduct of the sugar cane industry. Sugar cane juice is heated until to obtain crystals, the sugar. It is the solid residue that is not transformed, always very loaded with sugar, which will be distilled and will then create to traditional rum.
More than 90% of the rum volume produced in the world is made from molasses.
Vesou extraction (crushing)
The fresh cane is crushed by a series of crushing mills (3 or 4 usually) to separate the cane juice (vesou) from the fibbers remaining after juice extraction process (the bagasse).
The bagasse is often use as combustion for the furnaces which heat the water for the boilers and transform it into vapour. This vapour is use in particular to run the vapour machine which activate the crushers and the distilling columns.
The vesou is gathered in a drainage system for filtering and pumped on to the fermenting vats.
The fermentation process
The fermentation is carried out using yeasts and lasts in the majority of cases between 24 to 48 hours. During fermentation, the sugar present in the sugarcane is transformed, due to yeast activity, into alcohol. The aromatic elements which will characterize the rum start to appear during the fermentation process.
A sugarcane “wine” (also called moult) is produced with a 4 to 6° of alcohol.
The moult will quickly be sent for distillation.
The distilling process
The distillation is carried out in a pot still or distillation column.
The principe of the distillation is based on the fact that alcohol is a more volatile product than water. The water boils at 100 degrees, the alcohol evaporates from 78.4 degrees. It is therefore sufficient to heat gradually, at more than 78 ° and less than 100 °, a fermented liquid, therefore containing a certain amount of alcohol, so that the alcohol separates from the water and evaporates. The liquid alcohol is then obtained by causing the condensation of the alcohol vapors by cooling.
The method consists in heating the wine in the aim to vaporize the volatile components, mainly the alcohol, and then to condense them.
Before its introduction in distilling column, the wine is brought to a temperature of 70°C.
Introduced into the top of the column, the wine descends by gravity from one plateau to another, heating up when in contact with the steam which is introduced at the bottom of the column.
The alcoholic vapours are then recovered at the top of the column and cooled.
At the exit point of the distilling column, the rum is colourless and of 70° alcohol by volume.
Distillation allows to obtain pure alcohols, but the alcohols for drinking always contain a certain proportion of water which reduces the alcohol degree, and non-alcoholic elements which give to each rum a share of its originality, its taste and aroma.
The distilling column is the heart of the process. The column gives to the rum its own characteristics.
The white rum is the rum of “output” of still or distillation column. White rum is marketed after a few months during which the degree of alcohol is reduced to 50, 55, 62% alcohol by volume.
The quality of the white rum depends mainly to the care and attention given to the distillation.
Old or aged Rum
Old rum is a rum who has benefited a number months of aging in oak barrels before being bottled. This rum is known as either “élevé sous bois” (stored in wood) or aged.
From contact with wood, rum acquires a more or less dark color and a certain aromatic bouquet.
Evaporation losses in tropical climates are high. So, the “Angel’s Share” is the amount of distilled spirits lost to evaporation from the barrel or cask into the air as the rum ages. Angels’ share can reach 4 to 7% per year. The technique called “ullage,” which consists in topping up casks with rum from the same source, is used to compensate for natural evaporation, in order to preserve the volume to surface ratio.
Some rums are said “vintage” and carried the date of their year of distillation.
The rum called “out of age” is used for old rum that stayed at least 4 years in oak barrels and result from a blend of rums of different years.
For the aged agricultural rum, the rhum ust be placed in an oak barrel a minimum of 3 years for the VO label (rhum vieux), 4 years for the VSOP label (rhum très vieux) and up to 6 years for an aged vintage XO label rum (rhum hors d’âge).