Rum is sweet!
It’s a common refrain: “Rum is sweet because it’s made from sugar cane!” Yes, rum is made from sugar. But so is every other type of spirit like bourbon, scotch, gin, vodka, cognac, and tequila. All are derived from sugar, the key element in fermentation, yet you never hear about them being sweet. Confused?
Distilled spirits are made by converting raw materials such as grains, agave, fruit, or sugar cane into a solution of ethanol, flavor compounds, and water. Ethanol, also known as ethyl alcohol, is the “good” alcohol that makes us tipsy when we consume a bit too much. In fact, a spirit’s proof (e.g. 80 proof, which is 40% alcohol by volume) is just an indicator of how much ethanol is present.
The ethanol in a spirit comes into existence very early on, during fermentation—the chemical process that turns sugars into ethanol. Sugar and yeast go in, ethanol and other organic compounds (but mostly ethanol) come out. The key player here is sugar. Without sugar, there is no fermentation and therefore no ethanol.
Whiskey makers cook grains (barley, wheat, rye, corn, and so on) with enzymes to convert the starches into sugars. Mezcaleros cook agave piñas to convert the complex carbohydrates into simpler, fermentable sugars, the precursors to mezcal and tequila. Brandies like cognac or pisco begin with crushed grape juices, which (no surprise) contain sugar. Regardless of the source material, it’s always converted into an abundance of sugar, which is then fermented. Rum makers have a leg up here because they start with sugar in the first place.
A properly executed fermentation converts nearly all of the sugars in a mash into alcohol and other non-sugar organic components such as esters, which we spirits lovers perceive as flavor. By the time fermentation completes, very little sugar remains in the mash. Even if the fermented mash had residual sugar, very little would make it past the distillation process. Straight off the still, freshly distilled alcohol—regardless of whether it’s whiskey, tequila, brandy or rum—has essentially no sugar in it. There you have it: Rum is not inherently sweet!