Why does gin and tonic taste so good?

Refreshing and yummy.
Refreshing and yummy.
Image: Shutterstock/Brent Hofacker
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Matthew Hartings hates gin. “Something about that flavor doesn’t sit right with me,” writes Hartings, a professor of chemistry at American University. He also hates tonic. “It is too bitter for me. I just don’t understand how people can drink tonic water.”

But, if you mix the two, you make one of his favorite drinks: the G&T.

The first G&T was made in India. Tonic is nothing but water mixed with quinine and sugar. (Carbonated tonic water came later.) During the Raj, when British soldiers were supposed to ingest very bitter quinine as an anti-malarial, they realized sugar, water, and gin would make it palatable. Quinine was superseded by better anti-malarial drugs, but G&T remained a popular cocktail.

Why does it taste so good?

The answer is in the underlying chemistry. Hartings explains that the chemicals responsible for the flavors in gin and in tonic, although different from each other, nonetheless come in two kinds of broadly similar chemical structures—the reds and the purples in the diagram below. Gin has a wide variety of such chemicals, while compared to tonic’s quinine, but it’s the combination that’s important here.

Image for article titled Why does gin and tonic taste so good?
Image: Matthew Hartings

Similar types of molecules attract each other, and dissimilar molecules repel each other (just like oil and water). In the figure above, the purple molecules are like flat pieces of cardboard, which creates attraction between them, whereas the reds are more like out-of-shape cartons, and attract other reds. The reds in gin attract the reds in tonic, and the same with the purples. The attraction between these molecules creates aggregates, which taste different from how the substances taste on their own.

This principle is used for all kinds of “food pairing.” As we’ve reported before, there are other combinations based on the chemistry of taste molecules that you might want to try:

Finally, if you are looking for a great G&T recipe, Quartz’s mixologists recommend this one by Dave Arnold, the author of Liquid Intelligence:

What you need: standard highball glass, 1.75 ounces (about 50 ml) of gin, 3.25 ounces of tonic water, a wedge of lime, and ice. Put the glass and the gin in the freezer ahead of time.

How to make it: The order matters for better mixing. Cut a lime into quarters. Pull glass and gin out of the freezer. Pour gin first. Add tonic water slowly. Squeeze as much of the lime juice from the wedge as you can. Fill the glass with ice cubes and lay the wedge on top.

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