Every cocktail served in every bar around the world owes its existence to yeast. These microscopic fungi live by digesting sugars and converting them into alcohol and carbon dioxide. Almost any plant food imaginable can be used to provide sugars for fermentation, from potatoes to grain, but the most concentrated source of sugars is sugar cane. Logically enough, cane is used to produce several kinds of liquor.
Rum
Rum is the best-known and most common liquor produced from sugar cane. It is fermented from either molasses or sugar cane juice, distilled to as much as 95 percent alcohol by volume, and then bottled at 40 percent. Some rum is bottled unaged, but most is aged in oak barrels for at least one year, and some premium brands for as long as 30 years. Like any spirit, rum stops aging when it is bottled. Most commercial brands are a mixture of inexpensive, briefly-aged spirits mellowed by a smaller quantity of aged rum.
Cachaca
Cachaca is the national liquor of Brazil, a major producer of sugar cane. It is a clear liquor, distilled from sugar cane juice, and Brazilians draw a clear distinction between cachaca and molasses-based rums. There are two broad categories of cachaca. The inexpensive mass-market product, produced cheaply in great volume, is referred to as industrial. Artisanal cachaca, on the other hand, is a carefully aged spirit comparable to premium liquors from other countries and sources. Its taste is unlike rum, retaining a distinct sugar cane flavor.
Guaro
Guaro is a Costa Rican cane spirit, sometimes called aguardiente in other countries. It is also distilled from sugar cane juice rather than molasses. It is a clear spirit, distilled to a high degree of purity before bottling. Its flavor is very neutral, and in practical terms it is more a cane-based vodka than a rum. The Costa Rican government has a monopoly on the legitimate production of guaro, but illicit home-distilled guaro is common.
Mekhong Whiskey
Mekhong whiskey is an unusual branded spirit, produced in Thailand since 1941. It is little known to Americans, except those who have traveled or served in Southeast Asia. Despite the name, the liquor has more in common with rum or guaro than true whiskey. It is fermented from a mixture of 95 percent sugar cane juice and 5 percent rice, with the addition of a proprietary blend of local herbs.