MadSci Network: Biochemistry

Re: why do our tongues hurt more when we drinking sodas after eating spicy food

Date: Mon Aug 28 12:03:34 2006
Posted By: Mark D. Sullivan, Faculty Physician
Area of science: Biochemistry
ID: 1155575711.Bc

Hello Cates,

That is something I think everyone should know. I don't know how many times I see it when someone eats something spicey, then grabs a soda, then they feel it getting worse. Well, it is all due to a compound called capsaicin, which is produced by the capsicum peppers, or chili peppers. These are as simple as a green bell pepper, to a habenero chili, and range from no spice to downright on fire hot.

This little chemical is hydrophobic (which means it does not disolve in water), so it acts somewhat like an oil. It is found in the membrane of the interior of hot peppers, that white part on the ridges you see when you cut it open, and not actually in the seeds as previously thought. Not to say the seeds are not hot, they are just coated with the oil from the membrane.

So what happens when you eat a pepper is that the oils cannot mix in with your saliva, which is mostly water. So they coat your tongue and activate your pain receptors, giving that sensation of heat and pain. Next you reach for water, or soda in your case, and take a big swig. You may get some temporary relief, but then the pain comes right back. That is because, as I said before, the capsaicin cannot disolve in water and be removed from the surface of your tongue. Soda is water-based as well, so it doesn't help, the carbonation has little to do with it.

What really helps is drinks with fat in the them. The East Indian culture got this right by making drinks or side dishes of a milk or yogurt base to follow up a hot dish. This allows the capsaicin to disolve in a substance high in fatty compounds, and be removed from the surface of the tongue. Beers are often paired with spicey food as well, but even though these are water based like a soda, the ethanol has some solvent properties which dissolve the capsaicin and also remove it from the tongue surface. Once the capsaicin gets into your stomach it does not cause the same degree of pain if any as the lining of the gut lacks the same receptors as found on the tongue. Upset stomach after a spicy meal is due to another mechanism altogether, which at this time I will not get into.

The basic chemistry lesson is "like desolves like." Take for example salad dressings, to keep with the food theme. You can't mix oil and water as you know, they seperate quickly. But mixing oil with wine makes a pretty good dressing cause again the ethanol allows some mixing. Add in a cream of some kind with an oil (and some other herbs for flavor of course) and you get complete mixing.

The uses of capsacin are wide, including medical treatments for diabetic neuropathy, and pepper spray for self protection. So next time you eat a spicy meal, I recommend a mango lhassi with indian food and a thai iced tea/coffee with thai for a follow up drink. They're good all by themselves as well. Bon appetite!


Here is a website on capsicum peppers

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