How is spiciness processed by the body? how can one pepper be so much “hotter” than another? why does the taste produce a burning sensation?
In: Biology
Why spiciness creates a burning sensation is actually because it is your taste buds dying. Don’t worry, they grow back after about two weeks. That is, however, the reason why if you continuously eat spicy food you don’t really feel how spicy it is. However, if you stop for a while to let your tongue recover and then go back to it it will feel spicier than it did before.
*[edit] take the above paragraph with a pinch of salt as what I learned may have been erroneous, and I apologize for perpetuating information that may not have been wholly correct. I thank those who have corrected me below except those who obviously cannot keep a civil tone, you know who you are.*
Why some peppers are hotter than others is because of how high capsaicin content it has. That is the active chemical that is responsible for making peppers feel hot. The higher the level the spicier the food and the higher it rates on the Scoville grade for spicy food. However, other spicy compounds do exist, such as allyl isothiocyanate which is found in mustard, horse radish or wasabi. They have a very different kind of heat, one that hits you like a punch and then goes away rather quickly, as opposed to peppers which can linger for a long time.
Each taste bud in your tongue is covered with loads of receptors, but the receptors don’t just sense tastes. There are receptors for texture, temperature, temperature changes, and chemical damage etc. There are many different receptors to enable us to sense many different stimuli and many of the receptors can be activated by more than one thing. (Imagine a lock that is built to open to a couple of different keys without knowing what the keys might be shaped like).
One receptor is the VR1 receptor. It seems to primarily be geared toward damage to help us protect our tongue. It can be activated by acid or high temperatures, and when it is activated our brains interpret is as burning pain. As a fluke, peppers have a chemical in them which binds to the VR1 receptor. Because this receptor is made for sensing damage, your brain can only interpret the signals it sends as damage.
But capsaicin is not damaging the receptor just by binding to it. The reason someone becomes desensitized to capsaicin over prolonged exposure is because the receptor stops responding to it as much, so more capsaicin is needed to get the message through.
Capsaicin is an irritant chemical. Plants evolved it to avoid mammals eating them. It is advantageous for plants to be eaten by birds: they fly and defecate seeds far away. If a mammal eats a plant, it pounds ground somewhere not far away. Therefore, plants evolved a chemical that irritates mammals but does not irritate birds, namely capsaicin.
Then humans came and discovered they actually enjoy the irritation.
Latest Answers