How chillies flavour food and make you ask for more

Consider for a moment what happens when you accidentally bite into a typical Indian green chilli. As your teeth damage the cells on the outer flesh of this remarkable fruit, flavour molecules that hint of floral and citrusy notes waft through the back of your mouth and up your breathing tube to be detected by the olfactory receptors in your nasal cavity. But as you bite through the insides of the chilli and into the whitish placenta to which the seeds are attached, something else happens. A family of diabolically smart molecules called capsaicinoids gets to work.

Evolution has resulted in our mouths having a ton of different sensors and receptors, all aimed at preventing babies from putting dangerous things into their mouths. We have bitterness-detecting taste buds whose primary goal is to prevent you from eating poisons, most of which tend to taste bitter. We also have heat and pH receptors (called TRPV1) to prevent you from eating food that is either blazing hot (high temperature) or strongly acidic, both of which will, to put it mildly, damage your innards significantly.

The family of molecules called capsaicinoids has a fantastic trick up its sleeve. They neatly fit into these heat-detecting receptors, turning them on. A quick biochemistry lesson here—sensors in the mouth use a lock and key mechanism. The receptor is typically made of proteins with a three-dimensional shape that neatly fits into certain molecules, the ones we want to detect in the first place, and once this fit happens, a signal is sent to the brain, indicating that the switch has been turned on.

And then the brain declares battle stations because it is under the false impression that the mouth is literally on fire. It sends out more blood to cool your face, causing your face to flush, and also causes you to perspire, which lowers your body temperature. This is why we use the word “hot” to describe the sensation of eating chillies although there is no actual increase in temperature involved.

But the brain isn’t done yet. One of the survival mechanisms we have evolved is the brain’s ability to balance pain with pleasure. When one is in pain, the brain counters that by releasing more endorphins, which helps you manage and overcome the pain. So, eating hot food has the same effect. The brain wrongly believes your mouth is on fire and gives you an endorphin rush, that feeling of immense pleasure that we are familiar with a few painful seconds after biting into a mirchi bajji in Hyderabad.

And this is why we are addicted to hot food. It is painfully pleasurable, and since the pain is an illusion, it has no long-term harmful effects. However, the endorphin rush works better in combination with a fully made dish that has other flavours than simply biting into a chilli.

At some point, you might want to wash off all the capsaicin stuck to your TRPV1 sensors, and it’s not uncommon for people to reach for the nearest glass of water. This is okay but capsaicin is not water soluble. What works best is a glass of milk. A milk protein called casein has the ability to bind with capsaicin and stop it from doing the biochemical equivalent of a child running up to someone’s house and ringing the doorbell (and then hiding in the bushes to do it again and again)

The chillies cultivated in India tend to be mostly heat and little flavour. With the exception of varieties like bhut jolokia, kanthaari (bird’s-eye) chillies and a few others, Indian cooking tends not to care too much about what variety of chilli is being used. Mexico, where chillies were first cultivated, has over 200 varieties, and they aren’t just used for heat. They have spectacularly complex flavour profiles, and one cannot generally substitute one chilli for another in a specific dish.

Fats reduce the perception of heat because they can dissolve capsaicin and reduce its ability to go and turn on the heat sensors in your mouth. This is why something like idli podi is always accompanied by ghee or sesame oil.

Red chillies are dehydrated versions of the ripe (thus red) fruit and tend to have less floral or citrus notes and more smoky and pungent notes in their flavour profiles. If you are bored with simply using the one-dimensional red chilli powder in your cooking, try this hack. Dehydrate fresh green chillies in your convection oven at its lowest temperature setting for several hours till they lose all their moisture. At this point you can let them cool and powder them to create green chilli powder, which has both the heat and the floral and citrusy flavours of the fruit.

A common misconception is that hot food numbs the senses and reduces the ability to detect more subtle flavours in cooking. It doesn’t. In fact, if the amount of heat is just right (and this obviously varies by individual), it will improve the overall experience of eating. As Marryam Reshii says in the book The Flavour Of Spice, if food is lacking in “namak and mirchi” in this part of the world, it’s considered bland. Everything else can be excused.

Meet the family
Meet the family
The science of flavour.
The science of flavour.
How do we taste chillies?
How do we taste chillies?
How do we douse the fire?
How do we douse the fire?
Know your chillies
Know your chillies
Here's a quick recipe. Illustrations by Krish Ashok.
Here's a quick recipe. Illustrations by Krish Ashok.

Krish Ashok is the author of Masala Lab: The Science Of Indian Cooking.