When you've eaten something spicy, you take a quick gulp of water to damp the hotness. But after sometime, it feels hot again. Why?
The hotness of chillies
Chillies, bell peppers and other spicy ingredients in food cause its ‘hot’ness. This is because of a substance called capsaicin. The human tongue has many nerve endings called receptors that detect different tastes like sweet, bitter, sour and salty. One kind of receptors detects how warm the food is. Capsaicin irritates this receptor, causing the tongue to feel ‘hot’.
The nature of capsaicin
Capsaicin, like any other organic substance, has a complex structure. One end of it is made of a long, straight chain of carbon atoms. At the other end, there is a ‘benzene ring’, six carbon atom linked together in a circle. The two linked by an ‘amide bridge’. As carbon has a valency of four, there are different atoms attached to each carbon atom.
The long chain part of capsaicin has a particular property. It is hydrophobic, i.e. it does not dissolve in water. When you drink water, though it cools the tongue, it cannot dissolve and wash away the capsaicin. Therefore, the feeling of ‘hot’ness returns.
Removing the ‘hot’ feeling
Hydrophobic substances dissolve only in other hydrophobic substances like oils and fats. Hence if you wish to remove the hotness after eating spicy food, eat a little butter or cream, and keep it on your tongue for some time. It will the dissolve the capsaicin and remove it from the receptor.
Here are two interesting facts for you to remember. Birds like parrots do not have the capsaicin-sensitive receptor on their tongues; that’s why they enjoy chillies so much. By the way, capsaicin is related to another substance called vanillin, the flavoring agent commonly used in ice-creams!
When eating chilly, to remove the hotness, keep some butter or cream on your tongue for some time.