Antiquated as it may sound to contemporary ears, oleo saccharum isn’t all that ancient. Its name is Latin for “oil sugar,” but a Roman citizen would have no earthly clue what it’s used for. Instead, you’d have to ask a bartender, who would probably abbreviate it as just “oleo” and start going on about Jerry Thomas and other co*cktail arcana. They’d explain that it’s a critical flavoring component of classic punches—as old as co*cktail culture itself, really, but not quite as old as Pliny the Elder. And it’s nothing more than a syrup made of citrus peels and sugar.
Many sources claim that the first mention of oleo saccharum was in 1670, when Hannah Woolley’s recipe for Limonado called for lemon “pill” to be “brewed together” with sugar and other punch-like ingredients, but it wasn’t until the 19th century that we find a co*cktail book describing a method for making it. Richard Cook’s Oxford Night Caps, published in 1827, includes several recipes for punch, calling for the reader to “extract the juice from the peeling of a lemon, by rubbing loaf sugar on it.” And then Thomas, the so-called “father of American mixology,” popularized it in his canonical Bar-Tender’s Guide edition from 1862, which includes instructions to “rub the sugar over the lemons until it has absorbed all the yellow part of the skins.”
What does oleo saccharum add to a drink?
If you’ve never heard of oleo before, you might wonder why anyone would go to the trouble of rubbing a loaf of sugar on a lemon when you could just squeeze the damn juice and mix it with some sweetener. A fair question! But the compounds found in the fruit are different from what’s trapped inside the orange and yellow skins.
What we typically call the peel or rind of citrus fruit is made up of the epicarp (also called the flavedo) and the mesocarp (also known as the albedo). The flavedo is the zesty part—the outermost layer of the fruit that’s full of tiny, flavor-packed oil glands—while the albedo is the bitter, spongy layer commonly referred to as the pith. The juice contained in the vesicles beneath the peel have a different chemical composition than the essential oils in the flavedo, resulting in a different bouquet of volatile organic compounds (though both are quite high in limonene, one of the most common terpenes in nature). This variance in composition means that citrus oils can have more floral and herbal characteristics than the fresh, tangy flavors found in citrus juice.
If you’ve ever made a martini with a lemon twist, you probably understand the concept already. Twisting a lemon peel over a co*cktail bursts those teensy flavedo glands, releasing a fine mist of concentrated essential oils over the surface of the drink. It won’t taste sour or lemonade-ish, as it would if you’d added lemon juice; instead, the twist adds a suggestion of citrus rather than a command. (Muddling a peel accomplishes the same thing, while flaming a twist alters the character of the oils.)
