We all know when something is spicy, but few of us actually think about the nature of the spice. In fact, there are 3 categories of spices.
- The first is wasabi, mustard oil, and horseradish, which is volatile and the vapors travel up the to your nasal cavity. It first stings your tongue, then it clears your sinuses.
- The next is found in chili pepper. It contains capsaicin which causes a burning sensation like in tabasco.
- The third is found in things like black pepper and Schezuan peppercorns. It is less volatile and doesn't cause the burning sensation, rather a numbing sensation. I experience this at China Village.
All spices are not created equally. To create the most potent and deadly food, you could mix all 3 types. That way you get the burning and numbing experience while your nose hurts!
The receptors that are sensitive to spice cross paths with nerves that monitor temperature. As you eat spicy foods, the brain gets confused and interprets the signal as being heat related, that's why you "feel hot" even though you're at a normal temperature. The brain panics and releases sweat to cool down the body, even though you're not hot. In addition, it also causes the body to release adrenaline which increases your heart rate, dilates your eyes, and makes your brain focused and attentive.
So what can you do when it burns and you're all sweaty? Three common recommendations are ice, milk, and bread.
- Ice should slow down the receptors (it lowers the free energy [delta G] in the receptors and there is less signal firing in the nerves).
- Next is milk. Spicy ingredients are usually oil based (mustard oil, chili oil). The fat in milk dissolves the spicy compounds and carries it away from the tongue. I have not tested it, but skim milk should theoretically be less effective than 2% milk. If you know of any other drink that contains fat, that would work as well. Another benefit is that it is cold, which works in a similar way to ice.
- Bread soaks up things through capillary action, like a sponge. It soaks up liquid with the spicy compounds and carries it off as you swallow it.
Another way to avoid spice is that since it is often dissolved in oil, you can remove the oily layer in spicy foods. You can skim the oil layer on top of beef noodle soup and most of the spice will go with it. The watery part contains some remnants, but is much less potent in general. You can take advantage of this by taking extra oil from the beef noodle soup if you want it spicier or add more chili oil.
If you don't remove the compounds, they accumulate on your tongue. That's why the burning feeling builds up as you eat more. After sustained firing, the nerves get depleted of neurotransmitters and the signal firing slows down. That's why after a critical threshold, you don't feel the spice and your tongue "becomes numb" and insensitive to spice. This is a common experience at China Village.
One final warning is that capsaicin can be absorbed through other tissues. It can be absorbed through skin and especially the eyes (like pepper spray). If you are cooking peppers and say you cut an onion for the dish and you tear up....DO NOT TOUCH/WIPE YOUR EYES. The eyes are particularly sensitive and it doesn't take much to get an intense burning feeling in your eyes.