Elaboration of Rum
Rum is elaborated by fermentation of the cane juice (vesou in french) or from the molasses that is the residual liquid after the crystallization of the sugar in the cane juice; the molasses contains around 5% of sugar. Some countries must import molasses to produce rum. Anywhere that there is not a developed sugar industry or impure molasses is used, a low quality liquor is produced called tafiá that is not considered a real rum and is not exported.
The necessary sugar for the fermentation is all ready in the raw material (molasses), and the rum keeps better the original flavour from the raw material than most of the liquors. The characteristic flavour of specific rums is determined by the type of yeast used in the fermentation, the distillation method, the aging conditions and the blends.
The sugar cane, Saccharum officinarum, is an spice from the family of the grasses (gramineae), native from Southwest Asia (possibly form New Guinea). The plants needs 12 – 18 months to maturity and are harvested when their contain in sugar reaches its maximum
The harvest takes place cutting the canes as near to the ground as possible. In the same places, first, they burn the fields to eliminate the dry leaves, or to scare the snakes, this facilitates the cutting of the canes. The cutting method depends on the size of the property and the nature of the land – the hand cutting with machete is actually used very much, where, for example, the field is irregular or very small to benefit from mechanization. The plant regenerates issuing shots that grows in new stalks.
Once the canes are harvested the leaves and the higher end (cogollo) are taken off and transported to the mill. The canes must be grounded as soon as possible to avoid dehydration and deterioration of the sugars.
In the mill, the canes are washed, cleaned and cut in small pieces to facilitate the extraction of the juice. The canes are passed by different mills that extract the juice from the stalks. After the first grinding, a small quantity of water is added to facilitate the following extractions of the juice. The solid residue, called bagazo, is frequently recycled as fuel.
The cane juice (guarapo, “vesou” in french), of a green colour, is filtered to eliminate the residues of the cane and then is clarified to eliminate the solids in suspension. Then is heated and passes through evaporators to remove excess of water.
In the elaboration of agricole rhum the guarapo is used in the fermentation, but in the industrial rums the process of extraction continues to obtain molasses.
The derivatives of the sugar cane, as the juice, the virgin honey (cane syrup) and the molasses, contains a big number of minerals and organic components besides the sugars, This components are essentials in the production of rum, since many of the aromas and flavors characteristic to the rums, originates in them. Said in a simple manner, ¡without cane, there is not rum!
After boiling, a thick liquid is produced where the sugar is obtained from, that is consumed daily. The dark brownish liquid that is left is known as “light molasses” (light, as much in taste as in colour) or “first honey”. After a second boiling ,the molasses is darker and thicker and is called “second honey” or “black treacle” in English.
The molasses (word derived from the Spanish “miel”, honey) – known as “blackstrap molasses” in English, is the material from where the industrial rum is produced, is the result of the third boiling and is very thick, sticky, dark and a little bitter, although it still contains 55% of not crystallized sugar together with a big number of minerals and essential components for the aroma and flavor.1,5 gallons of molasses is needed to produce a gallon of rum.
Before to be able to distilled, the guarapo or the molasses, must be transformed on an alcoholic liquid (mosto or “cane wine”) through fermentation. The fermentation, done by yeasts, transforms the sugar (sucrose) in dioxide of carbon and alcohol (ethyl alcohol, in this case).
First, a solution is made with a content of approximately 15% of sugar diluting the molasses with water, the quality of this is important. Nevertheless, the cane juice is frequently fermented, in the “agricole rhum”, without adding water always that the natural content of sugar is low.
Although it is possible to use wild yeasts present in the air to induce the fermentation, most of the producers use improved stocks of yeasts to contribute to develop the characteristics of the different rums.
The rate of the fermentation maybe controlled through the temperature and depends entirely of the type of liquid fermented required by the distiller. If a light rum is wanted, the fermentation could be completed in 12 hrs, although the normal practice is one or two days. The slow fermentation – may take up to 12 days -produces a heavier type, especially if the initial mosto is reinforced with residues of previous distillations (vinaza o ‘dunder’) and/or limings that takes place in the pailas (large pan) of production of the sugar.
When the fermentation is completed, the resultant mosto has an alcohol content by volume between 5% and 9%.
It seems ironic that the water added to the molasses for the fermentation has to be eliminated by distillation. But this is the reason for the distillation: separate the water from the alcohol in a mosto. But also there is a second goal ,that is, to eliminate undesired agents in the flavor in form of ethers, aldehydes, congeners (impurities in the alcohol after the distillation) and acids, at the same time the desirables are retained.
There are two distillation methods used in the production of rum: distillation in still and continuous distillation in columns. In both cases the principle is the same: when mosto is heated, the alcohol evaporates at an inferior temperature than the water and these steams are gathered and condensed to originate the liquor.
- a) Distilation in still
The distillation in still is the most traditional and antique practice, and usually is reserved for premium rums of great complexity and subtlety.
The mosto is poured on a round copper pot that helps to eliminate the impurities. The pot is heated and in around 1 hour, the alcohol begins to evaporate. The steam is transported through a tube to a condenser. The remaining liquid is known as “simple distillation” (in French, also as clairin – “clerén”).
To obtain a higher alcohol content and a more pure final product, this liquid is processed for second time, producing a “double distilled” that may contain up to 85-90% alcohol volume. Nowadays, most of the rums produced with this distillation method are being produce from “double distillation”
- b) Continous distilation in columns
In contrast with the distillation in still, the distillation in column affords that alcohol is being distilled continually. This modern technique was introduced in the Caribbean at the end of the 19th century and definitely is the most used method, efficient and economical, producing stronger and purest liquor.
In his simplest form, the construction takes two columns called “analyser” and “rectifier”. Thanks to a clever design that uses the physics of the exchange of heat, mosto is separated on its constituted steams (analysed) in the analyser and the steam is condensed selectively (rectified) on the rectifier
Is possible to control the strength of a rum produced in continuous distillation since you can retire the condensed matter from the rectifier at different heights – the higher in the rectifier, the strongest is the liquor and it’s possible to distilled with 95% of alcohol volume.
In both distillation methods, the liquor produced is colourless. Any colour in the final product comes from the aging in oak and/or the caramel.
One of the fundamental precepts of distillation is that the highest the % alc. vol. in the distilled, the purest it will be. Therefore, the rums distilled in columns, highly, trend to be more vigorous, clean and dry with subtle aromas, and the original molasses is barely noticed (some of them come near vodka on its naturalist) and are described as light ones.
In contrast the rums produced in stills, that cannot be distilled with more than 85% of alc.vol., are relatively heavy, regarding flavoring agents.
Some producers uses blends of liquors obtained with both distillation methods. This is done trying to gather in the commercial product characteristics of both types of filtering
No doubt that placing a new clear liquor in a barrel or oak cask and leave it there for a few years improves it dramatically. And this not only applies to dark rums; also white rums can benefit enormously.
Like many other processes, the advantages of aging in oak barrels was discovered by accident. In the beginning, the crude liquor was bottled right after distillation, as it still happens with some of the actual white rums (although the usual is to filter and diluted them first).When the producers did produced more rum than what it was consumed on brief period of time, they began to store the surplus oak barrels that also were the right container to transport liquor. Soon was noticed that the white rum took colouration and developed a very superior taste.
The Aging is one of the most controversial aspect on the rum production. What exactly happens during the aging in one of the secrets of nature, the fusion of the liquor with the oak is magic. The rum absorbs tannins, taste and colour from the wood and, due to the porosity of the wood, that allows the rum “to breathe”, provoking complex oxidative changes in its chemical composition.
Actually, almost every aged rum is matured in oak barrels that were used to age whisky (especially American bourbon) and also barrels used with wine and cognac. The use of bourbon barrels to age rum is recent, since bourbon itself, was not aged in charred barrels up until 1860, 71 years after its distillation began in Kentucky in 1879.
The aging process is very complicated and, in many cases, surrounded by delicious legends of family tradition. The truth is, that during the aging natural changes happen as much physical as chemical. This changes called as maturation of the rum, serves to the improvement of quality of the distilled blends stored on the barrels. During this time, the air oxygen goes through the pores of the barrels oxidizing alcohols in aldehydes, and aldehydes into acids. As the times goes by, acids react with alcohols to produce ethers. The time required for the appropriate aging of the rum is in a direct proportion with its body. The “strong body” rums take more time for a proper aging than the “light body” ones.
The age or origin of the barrels has very little influence. What it’s sure is that a small barrel (normally 250 litres of capacity) is important for a good quality – the smallest the barrel, the bigger the influence of the oak. Any acquired colour in a rum that will be sold as white is eliminated filtering it through coal, before bottling.
As a rule the light type rums are aged between 1 and 3 years, while the strong ones need a minimum of 3 years. With the pass of the years, the content becomes softer, more mature and can be aged with success up to 20 years before begins to lose taste, always that the weather is fresh and humid. In hotter and drier climates, ages faster and rarely improves after 7 tropical years, being a tropical year equivalent to 2 or 3 years in fresher climates. But cares must be taken with the age declarations; it is true than the oldest the rum the best, but the location where it is aged is of great importance.
During the process some of the rum evaporates. This is known as “The Angel Portion” and also as the “Duppy’s Share” in Jamaica (“duppy” is a Jamaican term for a ghost or spirit). In mellow climates, this lose represents 2% of the barrel content yearly, but in Jamaica, for example, this value comes up until 6%. Due to this, it is only normal that the producers try to reduce the evaporation rate diluting the fresh liquor up to 80% of alc. Vol. before placing it to age. Luckily, the most subtle and attractive effects of the mature in oak take place with low alc. vol.
As much if it is white or golden, the rum is filtered before bottling. This eliminates the particles not wanted during the aging process while it improves the purity of its colour. For the rums being to be sold as white, the filtration trough active coal eliminates the dyes contribution of the wood of the barrels.
Some industries apply especial types of filtration, with specifics goals.
Barbancourt, from Haití, does a final filtration on cold for the rums that will be exported to non tropical countries and avoid, this way, that the change of climate will produce some sediments.
BLEND AND BOTTLING
Most of the commercial rums is a blend of different types and ages of rums, and even, rums from different countries, as it’s the case of the big volume international brands. If desired, during blending can be add caramel, spices and flavors (this last can be added before or during the distillation).
In this stage is when the expertise of the “Blender Master” appears and performs. Is enviable job it’s to make sure that every bottle will be consistent, as much in flavor as in quality – after all, the consumers expect and demand that it’s favourite brand taste exactly the same every time he buys it. Of course, the specifications of every brand are well kept secrets.
Once the different components have been selected and blended, are let to fusion (“marry”) for some time before, the strength is controlled for the bottling adding pure water, which quality is critical for the final result.