Can’t stand tonic, and the thought of drinking pure gin makes your stomach drop faster than the pound after Brexit? Yet when you mix the two together, you suddenly find yourself with an irresistible alcoholic bliss that has the power to turn your night into one worth remembering?
The answer is of course, science. To understand this perplexing phenomenon, we consider both gin and tonic separately on a molecular level.
Gin is a grain alcohol redistilled with juniper berries, which lends it its distinct flavour. Used for centuries as a tropical antiseptic, juniper berries can also help fight off coughs and lung congestion. The molecular composition of the seven essential oils (flavoured molecules) of the juniper berry are shown in the picture below. Note that it’s those wonderful OH sections that inebriate the drinker.
Source: Matthew Hartings
The source of the bitter taste of tonic is the molecule shown on the right, quinine. It has been used since the 16th century to cure malaria, but it was the British soldiers in India who first mixed it with gin, to make it taste less bitter, thus inventing the classic gin and tonic.
Winston Churchill himself once declared, “The gin and tonic has saved more Englishmen’s lives, and minds, than all the doctors in the Empire.”
So what happens when you mix the two?
A basic rule of chemistry is that molecules in solution attract each other if they have a similar structure.
As shown above, the juniper oils that are in blue are quite similar in structure to the blue part of the quinine molecule, in that they both have rings made of six carbon atoms.
These oils are therefore attracted to the ring part of the quinine molecule, whilst the red oils are attracted to the red part of quinine. Thus the juniper oil molecules will aggregate around the parts of the quinine molecule they are attracted to and mask the bitter taste of the tonic water. These clusters of taste molecules create a resulting taste that’s completely different to that of the two drinks independently.
The concept of foodpairing science was first discovered by Firmenich scientist François Benzi. At one of the first International workshops on molecular gastronomy in Erice, he got the idea that jasmine and pork liver, (which both contain the molecule indole) could possibly work well together. And they did!
Image Credit: Khymos
Gin and tonic is not alone. Many other food pairs exhibit such chemistry when their taste molecules are of similar structure.
White chocolate & caviar, strawberry & coriander leafs, pineapple & blue cheese, banana & parsley. Image Credit: Khymos
Flavoured molecules can be identified through analysis of the aroma by using a technique known as gas chromatography coupled mass spectrometry (GCMS). This is a two step process; first gas chromatography involves separating mixtures into individual components using a temperature-controlled capillary column. Then, a mass spectrometer is used to identify the makeup of the components based on particle mass.
Below is an excellent summary of known foodpairs. The ingredients are given in a circle size proportional to its prevalence in recipes, colour shows the category (e.g. fruit, meat etc) and finally the thickness of the line linking two ingredients is proportional to the number of shared taste molecules.
Flavour Network. Image credit: Nature
Celebrity chef Heston Blumenthal even started a restaurant whose menu is based on molecular cooking with food pairings, and the Belgian firm Foodpairing.com has built a business around identifying novel flavour combinations. For chefs such as these, aspirations toward culinary perfection may align themselves more with science than intuition and personal experience.
So the next time you try a food pairing such as pork and jasmine, that defies conventional sensibilities, you know that the secret lies in the underlying chemistry. Have a go at home – we especially recommend trying chocolate and blue cheese – both have 73 mutual flavour molecules. Yum, imagine the food pairing potential…
- A complete list of flavour pairings.
- Matthew Harting’s article on Gin and Tonic.
- A scientific food-pairing report by Nature.com.
- A comprehensive book “The Flavor Bible”.
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