Flavor Chemistry

Have you ever wondered why some ingredients taste so good together? There are so many classic examples. Honey and mustard, tomatoes and basil, even peanut butter and jelly.

There's some interesting science going on here. As we've already learned, different foods contain different molecules, which our brains interpret as flavor. And as a general rule, when two ingredients contain similar molecules, they'll taste great when you put them together.

Tomatoes and basil are a good example. They both contain a flavor molecule called linalool, which has a sweet, floral taste. Tomatoes and basil taste good together, because linalool unites them.

In the last few years, scientists have actually started to catalogue the molecules in different ingredients.

They do this using a specific technique called gas chromatography–mass spectrometry. We won't get into the details, but it's a great way to study the molecular composition of a substance.

Using this catalogue of different molecules, scientists are able to understand why certain ingredients go well together. They can also discover new combinations that no one has ever tried. For example, they discovered that white chocolate and caviar go well together. Why? Because they both contain molecules called amines.

Other examples of foods with similar components include bread and cheese, pear and honey, beef and garlic... the list goes on and on.

That scientific approach to flavor molecules if often referred to as food pairing. It's an exciting field, but it has to be said: when you're cooking at home, you can't get out a chemistry set every time you want to pair ingredients.

Luckily, there's another easy way to test for flavor molecules. Remember, you have a tongue and a nose for a reason: they're designed for exactly this purpose. Just take some ingredients, and taste them. On their own, or in combination. Do they go well together, or do they not?

If you want, you can get creative. Take a piece of beef, and add chocolate. Take another piece of beef, and add jelly. Take a third piece of beef, and add coffee. Which one tastes the best?

It's worth pointing out that similar ingredients aren't the only ones that go well together. Actually, combining opposite tastes can also work really well.

For example, a strong umami taste (pulled pork, for example) might go well with a sour taste (BBQ sauce) or a sweet taste (apple sauce). A sweet taste (meringue) might go well with a sour taste (lemon). A salty taste (peanut butter) might go well with a sweet taste (jelly).

Again, you'll need to experiment with this. But as a general rule: if a dish tastes too strongly of one flavor (sweet, sour, salty, umami, bitter), throw in an ingredient which brings something different to the pot.

Last time, we learned about two approaches to flavor combination: pairing similar flavors (e.g. beef and garlic) and pairing opposite tastes (e.g. honey and mustard).

This time, we're going to be learning about herbs and spices. These are right at the heart of good dishes. They allow for rich, complex flavor combinations that otherwise wouldn't be possible.

As a general rule, herbs are the leafy parts of a plant, while spices are made from other parts like roots, seeds, or bark.

Many plants produce essential oils in their leaves. These oils evolved as a chemical defense against animals and bacteria. But luckily for us, they also contain flavor molecules.

These molecules differ from herb to herb. For example, thyme has umami notes, basil is sweet, lemongrass is sour, bay leaves taste bitter, and so on.

As well as those main fundamental tastes, every herb also has more complex flavors, which are often unique to each particular herb.

For example, even though basil is sweet, it also has a peppery note to it. Sage, meanwhile, is sweet as well, but also distinctly earthy. Then we have mint – sweet again, but with a cool and refreshing finish.

There are so many different herbs out there, from regions all around the world. This vast selection can make it hard to know which ones to use.

Unfortunately, there's no set answer. It depends what type of food you cook, as well as your personal tastes. In other words, you'll need to work it out yourself.

Online resources can definitely help – look up flavor profiles for different herbs to discover how each one tastes. You also just need to start buying and trying. Which herbs taste best to you?

Slowly but surely, you'll build up knowledge of different herbs. And before you know it, your kitchen will be full of them: an arsenal of dried herbs in the pantry, and maybe even some fresh herbs growing on the windowsill.

One extra little fact, to remember about herbs, is that they diffuse their flavors much better in oil than water.

As we said, most of the flavor in a herb comes from the plant's essential oils. And oil and water don't mix.

That's why recipes rarely suggest that you add herbs to boiling water. If you cook them in oil, you'll usually get some stronger, punchier flavors.

There are some exceptions, like bay leaves, which can be thrown into a pot of boiling water when making a meaty stew. But as a general rule, most of the flavors you find in herbs (and spices too) are soluble in oil, not water.

Last time, we looked at herbs – the leafy parts of plants. This time, we'll be looking at spices – that's seeds, roots, and more.

Spices are generally more potent than herbs, and should be used in smaller amounts. But again, they're a kitchen essential, which bring depth and complexity to a dish.

Just like herbs, different spices can be categorized in terms of taste. Paprika tastes sweet, turmeric has subtle umami notes, sumac is sour, and black pepper is bitter (yes, unlike salt, black pepper is actually a spice).

Again, just like herbs, these spices also have more complex flavors, in addition to these fundamental tastes. For example, while paprika is definitely sweet, it's also slightly fruity, with an earthy heat to it. As always, the best way to learn about a spice, is to buy it and try it out.

We can't talk about spices without talking about spiciness – that's the prickling heat that you get from ingredients like chilies.

Spiciness isn't a 'taste'. Chilies contain a substance called capsaicin, which causes a burning pain in your mouth. That's literally all that's happening here: instead of tasting this molecule, you experience it as burning pain. If your mouth was genuinely on fire, it would feel exactly the same.

But this pain isn't actually bad for you. So if you enjoy the feeling, go for it.

As well as chilies, you can also get similar sensations from other spices, like ginger. This root contains gingerol, which also induces a burning sensation, but a more subtle one than the pain caused by capsaicin.

When we looked at the science of flavor pairing, we saw how you could either pair similar flavors or opposite tastes. This also applies when you're working with spices and herbs.

When you're crafting a dish, here's a useful rule: choose a pair of similarly tasting herbs or spices to use as a primary flavor. Then layer in two more, from different flavor areas, to add to the dish's complexity.

For example, paprika and cayenne pepper are both sweet and earthy. This makes them a good option for your primary flavor. Then add some oregano – it also adds to the earthy mood, but brings a hint of bitterness too. Last but not least, add a dash of thyme, for a little kick of umami.

As always, feel free to experiment. But you'll also find lots of great combinations of herbs and spices online.