Once upon a time, simple syrup wasn't so simple. Instead of using a mixture of just sugar and water, old timey barkeeps would sweeten cocktails with a more viscous sweetener known as gomme or gum syrup.
Today, most bartenders stick with plain old simple syrup and skip the more complicated gomme, which is made with a somewhat obscure stabilizer called gum Arabic. Even the most handlebar-mustachioed hipster mixologists rarely use this 19th century ingredient. And it's a shame. Gomme syrup gives cocktails a silky texture and a full mouthfeel, binding all the ingredients together to deliver a more sensuous drink. (I prefer the French word "gomme," because it's much more exotic-sounding than the English "gum" and does not conjure images of Hubba Bubba when I say it.)
What's Available to Buy
Small Hand Foods make a high-quality gomme syrup that's about $10 for 8.5 ounces. This small-batch producer also makes a pineapple gomme, an integral ingredient in Pisco Punch, and raspberry gomme, which they recommend subbing for grenadine in cocktails like the Jack Rose. Monin also makes a gum syrup, though I haven't seen it in any shops near me.
Why bother with gomme? It really shines in stiff cocktails that are made with mostly spirits, because it rounds out the alcoholic bite to give you a smooth sipping cocktail.
I recently did a side-by-side comparison of an Old Fashioned made with simple syrup and one made with gomme syrup. Each drink contained the same amount of sugar. They were both delicious because, hey, who doesn't love an Old Fashioned? However, the gomme syrup made the rye taste fuller and richer. The other Old Fashioned tasted less luxurious by comparison.
Gomme takes a little more work than simple syrup, but it's still just boiling and stirring (with a little waiting thrown in). The gum Arabic is an emulsifier, stopping the sugar from crystallizing. The Small Hand gomme is fantastic, but it cost more than homemade and I couldn't tell the difference between the two.
While some baking or natural foods stores carry gum Arabic, you will probably have to order it online. I felt a little weird ordering white powder from the internet, but Frontier Co-op's product has been recommended (and safely ingested) by many cocktail experts. One $20 package is enough to make more than 64 ounces of syrup.
You can also make your own fruit-flavored gomme syrups. Pisco Punch is traditionally made with pineapple gomme made by soaking pineapple chunks in the syrup overnight. But you can also try other fruits by steeping them in the syrup or even adding fruit to the pot with the sugar and water then straining it out before you add the gum Arabic. You can also experiment with gomme variations using different types of sugar like Turbinado or Demerara.
Spirits-forward cocktails like the Old Fashioned and Sazerac are the perfect way to use your DIY gomme syrup. But you could also use it in a Champagne Cocktail or Southside Cocktail or Daiquiri, since the brown liquors aren't the only ones given an indulgent boost by gomme. Delicious Pisco Punch is a classic use of pineapple gomme syrup.