The more capsaicin in foods such as chilli, the more pain receptors it will activate and the more intense the burning sensation will be.

Chilli peppers

Have you ever been tempted to try a chilli or a habanero pepper? Would you dare at least with one pepper from the padrón? The Spice, even the same food, it does not have the same effect on all people.

When we eat, many chemical compounds that flavor food dissolve in saliva. This causes certain taste receptors to be activated that are in the taste buds located on the tongue and palate.

These same molecules too activate smell receptors found in the olfactory epithelium. The gustatory and olfactory sensations are integrated giving rise to the perception of a flavor.

Taste also involves the activity generated from other receptors responsible for sensory modalities. For example, those that inform us about the texture and temperature (the taste of a good rice is also given by its cooking point and the temperature at which it is eaten).

Other receptors that are also activated are pain receptors. Pain sensors found in the lining of the mouth They warn us, for example, that a food or drink is too hot and could cause a burn. It is the same that happens on the surface of the skin.

Activation of these pain fibers causes a withdrawal reflex (spitting out what is swallowed) and an unpleasant burning sensation that is usually associated with tissue damage.

The person responsible for the sore tongue

But sometimes, those same pain fibers that are in the mouth are activated with chemical compounds (capsaicin, which we will talk about now) causing a burning sensation that is not only not unpleasant or activates a withdrawal reflex (if we like the spicy), but can become a real pleasure.

One of these compounds is capsaicin, an active ingredient in hot peppers (chillies, chili peppers). When this substance binds to TRPV1 receptors (transient vanilloid potential receptor 1) activates pain neurons. This receptor is also activated at temperatures above 42ºC. Therefore, the sensation that capsaicin evokes in the mouth is a burning itch.

TRPV1 receptors were described for the first time at the end of the last millennium, leading to the discovery of other members of a large family (transient potential receptors or TRPs) involved in stimulus detection that cause thermal sensations, touch and even pain!

By way of curiosity, the impact of these discoveries on sensory neurophysiology It is such that it has deserved the award this year of the Nobel Prize in Medicine and Physiology to Doctors David Julius and Ardem Patapoutian for their contributions in this field.

Now we know that the more capsaicin there is in a chilli, the more TRPV1 receptors you will activate and the more intense the burning sensation will be. We also understand why if we touch our eyes after having handled chilli we will feel a horrible burning sensation that can make us cry: we have many TRPV1 receptors in the cornea.

Why are there people more tolerant of spicy?

Yes OK perceptions are always subjective, the Scoville scale (originally described in 1912) measures hotness in SHUs (“Scoville Units”) and helps to know how hot a chilli is going to be.

Currently, very advanced techniques are used that we accurately indicate capsaicin levels from different edible species of the genre Capsicum.

Maybe Carolina Reaper, with the highest levels so far described (1.5 million SHU), may not be suitable for all audiences. But the Padrón peppers, if they are hot, do not reach 5 000 SHU. What can you do if you can’t stand the itch?

Capsaicin is lipophilic in nature, that is, does not dissolve in water. Therefore, depending on what we drink, we could amplify the effect of capsaicin by making it reach more areas of the mouth.

Milk, water, or sugary drinks?

It is popularly accepted that milk is the best remedy to counteract itching because capsaicin, lipophilic in nature, when dissolving in the fat part of milk or being neutralized by casein (also lipophilic), would lose its effect.

However, there is no scientific evidence to support that this is the reason. What is true is that, as shown by a recent study, in general, any drink is able to reduce the sensation of itching evoked after consuming spicy tomato juice.

These authors, like others before, confirmed that milk does indeed have a good anti-itch effect. In addition, they add that this is independent of its fat content (as both whole and skim milk achieved the same effect). Therefore, it is possible that some component of the protein fraction of milk (and not the fat) has some neutralizing effect on capsaicin.

If the taste of milk is going to alter your taste perception, you can also mitigate the itching sensation with sugary drinks. Whatever your drink of choice to accompany a spicy dish, there is still no explanation that supports the anti-itch effect of any of them.

* This article was originally published on The Conversation.

*Carolina Roza, author, pProfessor and researcher in Physiology at the University of Alcalá.