It’s not your imagination: Gin and tonic water actually taste better together than apart. The duo is greater than the sum of their parts thanks to their chemical makeup. And your nose, mouth and brain are wired to light up when they encounter the cocktail. Now if only food scientists could figure out exactly why.
“One of the reasons I love talking about food chemistry and the Gin & Tonic problem in particular is that we don’t know,” says Matthew Hartings, a faculty member in the department of chemistry at American University, who has put a lot of thought into the mystery of the delicious G&T. “We have some ideas, but a full account of it, we don’t know.”
Let’s start with what we do know. What we taste, and more importantly what we smell, comes from molecules inside the drink. In the case of a G&T, these molecules come from botanicals, primarily juniper, infused into the gin (drawn out by ethanol in various ways during distillation) and from quinine in the tonic, which gives the mixer its unique bitter taste. These molecules are delivered to our mouths by drinking or to our noses (where most of our flavor receptors actually are) by evaporation. While ice adds a cool crispness to the taste, it also dampens the molecular activity, which is why extra bubbly tonic helps to deliver more flavor, by transporting the chemicals up the liquid and into our mouths.
The next piece of the puzzle is how we taste. Molecules in your drink fit into protein receptors in the nose and mouth, triggering signals that go to your brain and giving you a sense of taste and smell.
But we’re not simply talking about individual molecules in the case of gin and tonic. We’re talking about aggregate molecules, which combine individual chemicals into new molecules that taste completely different. Unlike oil and water, which separate violently, the molecules in gin and tonic water naturally attract one another.
“When we start talking about how molecules are attracted to one another,” Hartings explains, “the general rule of thumb is if two molecules look like one another, and they have the same patterns of carbons and hydrogens and oxygens, and they have the same backbones and substance, they’re going to be attracted to one another.” If you want to get into the scientific weeds about it, similar chemical structures generate electric dipoles that attract one another. If you’d like the Cocktail Science for Dummies version, just take a look at these graphics Hartings generated (highlighted to show similar chemical structures).