Originally posted January 28, 2011
January 28, 2011
I have a confession to make. I really don’t like gin. There is something about that flavor that doesn’t sit right with me. I tend to prefer vodka martinis (blasphemy, I know). If I do have a gin martini, I certainly want more than just a hint of dry vermouth in my drink. I also require olives. Copious olives. In that same vein, I don’t like tonic water either. In fact, I abhor tonic water. It is too bitter for me. I just don’t understand how people can drink tonic water. I realize that I’m probably oversensitive (a supertaster, if you will). I want to like each of these drinks; believe me, I do!
My noted aversions to both gin and tonic make it all the more incredible that I love gin and tonics. I can’t remember when I had my first gin and tonic. I just remember it being a revelation. A good gin and tonic, to me, is wonderfully crisp, strangely sweet, and aromatic. While they are considered a summer drink, I am perfectly happy to have one in hand any time of year. In fact, my fabulous wife made me a gin and tonic two nights ago. It was fantastic.
Why do I like gin and tonic but dislike both gin and tonic?
There must be some reason for this, right? Of course there is. And you can bet, if I’m writing about it, there is some science behind my inclinations. And in this case it all comes down to what gin and tonic each look like at the molecular level.
Let’s start with the gin. Gin is typically a grain alcohol that has been redistilled with juniper berries or other natural flavorings (citrus peel and other spices). While the alcohol itself lacks much flavor (think vodka), the primary flavors attributed to gin are those from the juniper berries. During the distillation, the alcohol is able to draw several oils – flavors – out of the cells in the berries. Some of the primary flavor oils look like this:
The essential oils of the juniper berry. (Top) From left to right: pinene, camphene, sabinene, cineole. (Bottom) From left to right: terpinene, cymene, terpinen-4-ol. If you’re not a chemist, the names aren’t important. The structures, however, are important, and I will bring them up again later. These are the molecules that give junipers, and gin, their distinctive flavors and aromas.
Tonic water is flavored with quinine. Quinine tastes bitter. It is a base (the opposite of an acid – see my post on pH and acidity from last week). Quinine was used to treat malaria from the 1600s all the way through the 1940s. It was the British living in India who first mixed quinine tonic with gin to make tonic more palatable. (Humans’ general aversion to bitter foods likely evolved due to the fact that many poisons are also bitter. Even quinine is poisonous in large enough doses. Don’t worry, your tonic water is perfectly safe.)
The chemical structure of quinine. Quinine is a basic compound. (Mixtures of water and quinine have a high pH.) Humans experience basic liquids as having a bitter taste.
When gin and tonic are mixed, quinine and the flavor molecules from the juniper berries combine to make a perceived flavor that is different than just the sum of the individual parts. The molecules from the gin and the tonic can do this because they look alike; the molecules are similar.
Molecules are Homosexual
Yes, you read that right. Molecules are homosexual. Molecules that are alike are attracted to one another. Molecules that look nothing alike tend to stay away from each other. You are all familiar with this phenomenon. We have all seen water and oil separating. This happens because water molecules are nothing like fatty oil molecules. After mixing, the oil molecules come together, forming droplets amid all of the water.
Oil and water separate upon mixing because they are molecules that are not similar. Note: water and oil molecules not drawn to scale. (Image modified from here)
Gin and tonics operate on this same principle, only in reverse. The difference being that the flavor molecules from the gin and tonic are attracted to one another. They are similar. Let’s have another look at these molecules.
These pictures, rendered differently, show how parts of the quinine molecule look like the different flavor molecules from the gin. The parts of these molecules that look alike (red matching with red and blue matching with blue) are attracted to one another. When they are mixed together in a gin and tonic, the molecules come together to create an aggregate. In the aggregate a quinine molecule is nestled up closely to one of the juniper molecules. These aggregates create a taste sensation that is completely different from just gin and tonic on their own. This is why a gin and tonic doesn’t taste exactly like gin plus tonic. (This is also the reason why I don’t do vodka tonics. Vodka has no flavoring other than alcohol, and the quinine from the tonic has no molecules to mingle with, which leaves the taste of tonic in my mouth.)
These molecular attractions are the reasons why other food pairings are so appealing to our senses. Martin Lersch (a professional inorganic chemist, by the way) has compiled a list of flavor pairings (some of them intuitive, some of them seemingly odd) on his wonderful blog on food science, khymos. (A quick note. Many of these are taken from articles from The Guardian by Heston Blumenthal, the man behind one of the most highly regarded restaurants in the world, The Fat Duck.) All of these flavor pairings “work” because each pair contains specific flavor molecules that are similar to one another. The attraction of these molecules alters their flavor profile. This effect was captured beautifully by a scene in Ratatouille.
Scene from Ratatouille where Remy creates a new flavor sensation by having a bite of strawberry and cheese at the same time.
The weekend ahead
Thankfully, we still have some bottles of tonic at home and some Bombay Sapphire (one humble man’s preference) in the freezer. I plan on going home and putting my knowledge of chemistry to good use this weekend.