Rum from the top of the world
Making of Rum

The Raw Material
Rum is produced from molasses, the final by-product in the manufacture of raw sugar from sugar cane - indeed, in many Caribbean islands, producers are legally required to be sugar refiners first and rum distillers second.

Sugar Cane, saccharum officinarum is one of the taller members of the grass family with the potential to grow up to 14 feet high under tropical conditions. In these hi-tech days, of course, much genetic improvement has been made to increase sugar content, or to give disease resistance, for example.

Harvesting takes place by cutting the cane as close as possible to the ground. In some places, the fields are first torched to clear away the dead leaves ("trash") or to drive out snakes, a process which also makes the cane easier to Map of the world showing the cane producing areas cut. The method used to do this depends on the size of the farm and the nature of the terrain - hand-cutting by machete is still widely used today, for example, where a farm is too hilly or too small to benefit from mechanisation.

The cane plant regenerates by sending out shoots ("ratoons") which grow into new stalks. As they reach towards the heat and light of the sun photosynthesis creates sucrose that is stored unchanged (unusual, since in most other plants, sucrose is converted to starch).

At the mill, the cane is chopped and then passed through a series of rollers and grinders that squeeze out the juice from the stems. The pulverised remains ("bagasse") are often used as fuel and can even be turned into chipboard.

The acidic, green-coloured cane juice ("vejou") is now heated and clarified before being pumped into evaporators which drive off excess water. It is then cool-boiled in a vacuum to create a syrupy mixture from which Grade A sugar crystals are extracted - the kind that we use to sweeten our coffee and tea. The brownish-black liquid that remains is known as light molasses (light in both flavour and colour), often used as a syrup for pancakes or waffles. After a second boiling, the molasses is darker and thicker - generally described as black treacle.

Blackstrap molasses, the stuff from which rum is made, comes from a third boiling and is very thick, sticky, dark and somewhat bitter, though it still contains approximately 55 percent of uncrystallised sugar along with a large number of minerals and non-sugar compounds essential for aroma and flavour. Approximately 1.5 gallons of molasses are needed to make one gallon of rum.

Before the molasses or cane juice can be distilled, it must first be turned into an alcoholic liquid by fermentation. This, in essence, is all about yeasts' partiality to sugar - put them in a warm, sweet liquid and they multiply like mad, secreting enzymes that convert the sugar into roughly equal quantities of alcohol and carbon dioxide.

First, a "live wash" with a sugar content of approximately 15 percent is created by diluting the molasses with water, the quality of which is really important. Cane juice, however, can often be fermented without the addition of water if the sugar concentration is low enough naturally.

n the same way that sugar cane has been technologically adapted to suit soil and climate, various strains of artificial cultured yeasts are used to contribute to the individual characters of different rums. However, many producers are quite happy to rely on the wild yeasts naturally present in the air to induce fermentation.

In some cases, notably where a heavy, dark style of rum is desired, "dunder" (the residue left in the still) or "limings" (the scum that forms on the surface of the molasses as the sugar is being extracted) may also be added for a more pungent flavour.

The rate of fermentation can be controlled by temperature and depends entirely on the style of "dead wash" (the fermented liquid) required by the distiller. If he wants a light rum, fermentation can be completed in as few as 12 hours, though a day or two is normal practice. Slow fermentation - which can take up to 12 days - produces a heavier type, especially when the live wash is reinforced with dunder. On completion of fermentation, the dead wash has an alcohol strength of between 5 and 9 percent.

It seems ironic that the water added to molasses for fermentation is then removed again during distillation. However, this is the ethos of distillation: to separate the alcohol from the water in a dead wash. There is a second objective, however, which is to remove undesirable flavouring agents in the form of esters, aldehydes, congeners and acids, while retaining the favourable ones.

There are two discrete methods employed in rum production: pot still distillation and column or continuous still distillation. In both the principle is the same: when wash is heated, alcohol vaporises at a lower temperature than water and these fumes are collected and condensed to give the spirit.

Pot Distillation
Pot distillation is the more traditional and time-honoured practice, tending to be reserved for the production of premium rums of great complexity, subtlety, and finesse. Each batch of wash has to be heated up separately and needs careful monitoring, so the process is low and quite costly as a result.

The dead wash is fed into a circular copper kettle which helps to remove impurities. Heat is applied and, after about an hour, the alcohol begins to evaporate. The vapour is piped to a separate cooler and condensed to give the spirit that, in most cases, is distilled a second time to purify and concentrate it further, yielding a distillate that can contain up to 85 percent alcohol by volume. The art of the distiller is important because the first and the last of the vapours that come off (the "heads" and "tails") contain many volatile poisons and unwanted fusel-oils. The distiller has to judge when to collect the safe "heart" of the distillate, a highly specialised job.

Column Distillation
In contrast to pot distillation, column distillation allows alcohol to be distilled continuously. This modern technique was introduced into the Caribbean at around the turn of the twentieth century and is quite definitely the more widely used, efficient and economical method, producing a stronger, purer spirit.

At its simplest, the construction comprises two column called the "analyser" and the "rectifier". Thanks to a clever design that utilises the physics of heat exchange, the wash is broken down into its constituent vapours (analysed) in the analyser and the vapours are selectively condensed (rectified) in the rectifier.

In practice, it's possible to control the strength of rum produced in a continuous still because the condensate can be drawn off the rectifier at various heights - the higher up the rectifier, the stronger the spirit and a distillate of 95 percent alcohol by volume is easily attainable. Incidentally, the spirit of either distillation method emerges water-white in appearance. Any colour in the finished product comes form wood-ageing and/or caramel.

Heavy versus Light
One of the fundamental precepts of distillation is that the higher the alcoholic strength of the distillate, the purer it will be. Highly rectified, column-distilled rums, therefore tend to be crisp, clean and dry with subtle aromas and only a whisper of molasses character (some even approach vodka in their neutrality) and are described as "light". By contrast, pot still rums, which cannot be distilled beyond 85 percent alcohol by volume, are relatively "heavy" in flavouring agents.

As a rule, the slower the fermentation, the heavier the rum because other micro-organisms have the chance to pitch in and work alongside the yeasts, contributing their own set of flavours. They simply don't have timeto do this during a rapid fermentation.

Put the new clear spirit into an oak barrel, leave it for a few years or so and there's no doubt that it will improve dramatically. And this does not apply to dark rum only. White rums can benefit greatly, too. An aged white rum though innocent-looking can harbour intensely deep, lingering and wonderfully integrated flavours.

Like so many processes, the advantages of oak-ageing were discovered by accident. In the old days, the raw spirit used to be bottled directly from the still which remains more or less true for today's unaged white rums (though it's now more usual to filter and dilute them first). When producers started to make more rum than could be consumed, however, the excess was stored in oak barrels that were also convenient vessels in which to transport the spirit. It was soon noticed that the white spirit soaked up colour and also developed a much superior taste.

Exactly what takes place during the ageing process remains on of nature's best-kept secrets, but the marriage between spirit and wood is magical. The rum saps tanning, flavour and colour from the wood and, because wood is porous, it allows the rum to breathe, causing complex oxidative changes to its chemical make-up.

The age or provenance of the barrel seems to make little difference, though once-used bourbon casks are popular and some are first re-charred on the inside. What is known for sure is that a small cask (normally 250 litres in capacity) is crucial to good quality - the smaller the barrel, the greater the oak's influence. Any colour acquired by a rum that is to be sold as a white style is removed by charcoal filtering before bottling.

As a rule, light-type rums are aged for anything from one to three years while heavy-types spend a minimum of three years in barrel. With each passing year, the contents become softer, smoother and more mellow and can age successfully for up to 20 years before starting to lose flavour, providing the climate is cool and damp. It ages much faster in hotter, drier environments and seldom improves beyond seven "tropical" years, one "tropical" year being roughly equivalent to two to three cooler-climate years. Age statements have to be treated with some caution, therefore: yes, the older the rum, the better it will be, but the place of ageing is also of great importance.

Over the years some rum is lost to the atmosphere through evaporation. This is known as the "Angel's Share" and also as "Duppy's Share" in Jamaica ("duppy" being Jamaican for a ghost or spirit). In temperate climates this loss accounts for about two percent of the contents of a barrel annually, but in Jamaica for instance, this figure climbs to six percent. It's quite normal, then, for producers to attempt to slow down the rate of evaporation by diluting the new spirit to about 80 percent alcohol by volume before ageing. Luckily, the more attractive, subtle effects of oak maturation happen to be extracted at lower strengths.

The cooperage, where the ageing barrels are traditionally fabricated, is filled with the sounds of hammering, a glorious stirring euphony not unlike the old, rhythmic Caribbean spiritual music. Coopering is an art in itself, although sadly it is disappearing in favour of automated barrel manufacture.

The majority of rums are created form a blend of rums of different types and ages, and, in the case of some of the large-volume, international brands, may be made up of rums form different countries of origin. Caramel, spices and flavourings are also added at the blending stage if desired (though the latter can be added before or during distillation).

This is where the expertise of the master blender comes into play. His unenviable job is to ensure that the contents of every single bottle are consistent in terms of both flavour and quality - after all, the consumer expects and demands their favourite brand to taste exactly the same every time he or she buys it. Naturally, the specification of each brand is a well-guarded secret. Once the various constituents of the blend have been selected and bulked together, they are allowed to "marry" for a while before being reduced to bottling strength by the addition of pure water. Here again, the quality of the water is critical.
Talking of strength, it's always wise to study the percentage alcohol given on the label before tucking into any rum with gusto. Some of them are so incredibly strong that you wouldn't want to breathe over a naked flame having taken even the tiniest of sips!
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