What is Rum?

Rum is a distilled spirit made predominantly from molasses. The first distillation of rum took place on the sugarcane plantations of the Caribbean and first mentioned, specifically, in records from Barbados around 1650. It was originally referred to as “kill-devil” or “rumbullion” but by 1667 was simply called rum. The legal definition tends to vary depending on the country of origin, so establishing a strict definition that applies to all rum from everywhere is impossible. What’s consistent, though, is that rum is always made from molasses, sugarcane juice, or other cane by-products. Initially, molasses was thought of as industrial waste, too heavy to transport from the islands, and therefore mostly dumped into the ocean. It was the plantation slaves that first discovered the molasses starting to ferment. It still had enough sugar to attract natural yeasts from the air; and the hot, wet climate of the islands was perfect for encouraging natural fermentation. By this point, distillation techniques were refined, and quite well-known so it was natural to take the fermented molasses and distill it.

In modern times, most distillers purchase molasses rather than make it themselves. Yeast and water are added to the molasses to create a “wash,” which is then allowed to ferment. Some distillers prefer to use wild yeasts, whereas others, use specific cultivated strains. Fermentation, of course, is the process by which yeasts convert sugars into alcohol. In modern spirits production, this process generally takes place in large metal tanks and is carefully monitored. Fermentation lasts from twenty-four hours to several weeks, depending on the type of rum being produced. Distillation can proceed using either a pot still or a column still. Pot stills are more traditional and less efficient (i.e. more expensive) than column stills. Generally, heavier rums are produced in pot stills and lighter rums in column stills, although some rums are a blend of pot and column.

A Sordid History

Sugar cane was first introduced to the Caribbean in 1493 by Christopher Columbus who was inspired by his father-in-law, a sugar planter on the island of Madeira. But it wasn’t until the decadent era of Louis XIV that Europe developed a real sweet tooth. That fueled sugar production in the Caribbean, and an ugly slave trade to support it. By the late 1600’s rum found its way into the slave trade of the American colonies and Europe. Slaves were brought from Africa and traded to the West Indies for molasses; the molasses was made into rum in New England; the rum was then traded to Africa for more slaves.

This was all during the Age of Sails, and all the European powers (British, Dutch, Spanish, Portuguese, French etc.) had colonial interests in the new world of the Americas. Thus, it also ushered in the era of piracy and state sponsored privateering.Historically, the association of rum and pirates was enforced because of the rum-rations given, by the Royal Navy, to its Privateers (replacing French Brandy). Many of the privateers later became pirates or buccaneers raiding Spanish flotillas. Since rum was in such great abundance and so inexpensive it became their beverage of choice. Excavations at Port Royal, Jamaica which was a famous pirate hang-out once dubbed “the wickedest city in the world,” turned up hundreds of rum bottles.

British sailors received rations of rum in 1600’s which was an administrative move that was wildly popular because rum was both stronger and it kept better than beer. It was so popular, in fact, that it soon began to interfere with the sailors’ competence, which led Admiral Edward Vernon to attack the “pernicious custom” of rum guzzling, which led to “many fatal effects” on sailors’ morals and health.

Vernon’s solution: dilute the rum and add citrus juice. Surprisingly, this made everyone happy, including the sailors, who were still getting the equivalent of five generous shots a day. The new watered-down drinkable was promptly referred to as “grog,” in reference to Vernon’s nickname, “Old Grogram,” from the weatherproof grogram coat he routinely wore. The addition of citrus to watered down rum, proved to be helpful in warding off scurvy as well.

By the 18th century, American colonists were not only importing rum; they were distilling their own.  As of 1770, according to one source, there were over 150 rum distilleries in New England, and the colonists, collectively, were importing 6.5 million gallons of West Indian (Caribbean) molasses, and turning it into five million gallons of rum. One estimate from the time of the Revolutionary War puts American rum consumption at nearly four gallons per person per year. Unfortunately, most of it wasn’t very good, but it did have the advantage of being cheap.

The exception was Medford rum. Medford—whether because it actually tasted better or because the Medford distillers were canny self-promoters—soon had a national reputation for high quality. Rival towns even attempted to boost their sales by stenciling “Medford” on their rum barrels. In 19th-century cocktail recipes that called for rum, often specified Medford as the rum of choice.

Excavations at Port Royal, Jamaica which was a famous pirate hang-out once dubbed “the wickedest city in the world,” turned up hundreds of rum bottles.

Factors that Influence Rum Styles

  • Agricole

Most rums were made using molasses from the Caribbean, however, during the Napoleonic Wars in the early 1800s, Britain imposed a blockade of France, and this blockade prevented the import of sugarcane from the Caribbean. As a result, French scientists devised a method for the industrial extraction of refined sugar from sugar beets, which, unlike sugarcane, could be grown throughout France and central Europe. This, however, left the sugarcane industry in Martinique and other French West Indies colonies with a quandary: its chief market for refined sugar had suddenly dried up. The plunge in sugar prices drove many producers into bankruptcy; sugar production declined, and less molasses was available for rum production. Distilleries in those islands turned instead to freshly crushed sugarcane juice. The product that resulted came to be known as “agricultural rum”—or rhum agricole. In this case, the sugar source carries a certain amount of terroir. Fresh sugarcane juice is prone to oxidation, so it needs to be produced near the distillery, and fermentation needs to begin straight away. Agricole manufacturers say that the use of local sugarcane carries some character from its growing environment into the finished product.

  • Yeast Type

Using wild yeast will impart certain characteristics of the local environment into the rum; characteristics that can actually change from batch to batch. To control such variables, some companies use specific cultivated strains that retain the same characteristics from generation to generation. The Los Angeles Times recently wrote about the yeast used by Bacardi, detailing how the Bacardi distillery smuggled its yeast out to Puerto Rico when its original Cuban facilities were nationalized by the Castro government in 1960.

  • Length of Fermentation

The other variable that yeast introduces is fermentation speed. Some yeast strains convert sugar to alcohol more quickly than others. The faster the molasses ferments, the fewer esters and congeners (the chemical substances that create flavor compounds) form.

  • Type of Still

Another factor that affects rum styles is the type of still used. Pot stills generally produce heavier rums, richer in the yeast compounds that create flavor. Column stills produce lighter rums, stripping out more of the flavor compounds. Column stills are more efficient and therefore less expensive to operate, but it’s important to remember this isn’t an either-or proposition. Some rums are started in pot stills and redistilled in columns, and some rums are a blend of pot and column.

  • Type of Barrel

The kind of barrel used for aging rum affects its flavor, too. Some rums are aged in new charred-oak casks; some are aged in used whiskey barrels. Some are aged in sherry casks; some in cognac barrels. All these contribute different flavors to the finished product. Not all rums today are aged, however those that are, much like whiskey, tend to be more highly regarded and more expensive. The longer a rum ages in a barrel, the more flavor compounds it will pick up from the oak.

  • Strength of Rum at Distillation and Bottling

Most rums on the market are bottled at 80 proof, or 40% alcohol by volume (ABV), but they’re typically distilled to a higher proof—anywhere from 85 to 95% ABV—and then diluted with water to achieve bottling proof. The rums with the richest flavors and bodies are those distilled to a lower proof—say 85% abv—and then diluted to a higher proof—say 43 to 45% abv.

Why is this so? When spirits are distilled to higher and higher proofs, the flavor compounds begin to degrade; a rum that comes off the still at 95% ABV will retain fewer flavor compounds than one distilled to 85%. Remember, a spirit distilled to 95% ABV is 95% alcohol and 5% other compounds. Some part of that 5% is flavor molecules. A spirit distilled to 85% ABV has 15% other, and therefore more room for flavor molecules.

When you take a rum distilled at 95% ABV and dilute it down to 40%, you need to add a lot of water, which, being water, carries no flavor. So you end up with a lighter tasting rum than if you start with a more flavorful spirit and add less water.


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