What Makes Food Spicy?

Food Science 101: The Chemistry of Capsaicin

Most people would agree that the creation of food is considered an art. While this may be true, the fundamentals of food—and of flavor—rely greatly on science and how the molecules in our food interact with the molecules of our bodies. That being said, consider this a lesson in the science of food. Today's topic: capsaicin.

What is capsaicin?

Capsaicin (pronounced cap-say-a-sin), an organic compound produced by the seeds in plants of the genus Capsicum, is the active ingredient that gives spicy food its fiery heat. Capable of bringing even the bravest of people to submission if administered in high enough a concentration, this natural irritant is present in all chili peppers and functions as an evolutionary defense mechanism against the one thing we do best—eat them.

Why the burn?

No lesson on capsaicin, or its effects, would be complete without a brief explanation of your body's primary instrument for taste—the tongue. Not only is the human tongue the strongest muscle in the human body relative to its size, but it is also home to the millions of microscopic receptors that make our sense of taste possible. In addition to the five tastes of bitter, sweet, salty, sour and umami, your tongue contains thousands of pain receptors, called VR1 receptors—capsaicin's prime target. Here's how it works. Capsaicin molecules in your food come in contact and bind to the pain receptors on your tongue. What ensues is a burning sensation, signaled by the brain, which is identical to what happens when you get your hand too close to a hot fire—it burns! The difference with the burn from capsaicin? No physical damage is actually done to the tongue. Kind of cool, right?

While many of you can appreciate a substantial degree of heat from the plethora of chili concoctions out there, sometimes the burn can be too hot. What can you do if you overstep your threshold for pain?


If you do fear a capsaicin "overdose," steer clear of the water glass. Though it would seem that a nice gulp of ice cold water will douse the flames within, think again. It will only make it worse. The reason is simple: capsaicin, as an oil, does not mix with water and will only spread the burn.

Sugar & Fat

Consider them culinary "S.P.F"—or Spice Protection Factors. The chemistry of why fat-laden foods will sooth the sting of capsaicin is just as simple as why water will not. While insoluble in water, capsaicin is soluble (which simply means it will dissolve) in other oils, such as those found in milk products and other fatty foods. Once diluted with other fats, the capsaicin molecules in your mouth are incapable of binding to the VR1 pain receptors on your tongue. As an illustration, imagine a broken play in football where your quarterback—represented here by capsaicin—gets sacked by the entire defensive line.

Much like with fats, sugar too will block the capsaicin from binding to pain receptors and is the reason why sweet wines are generally paired with spicy foods—their high residual sugar content coats your mouth and helps prevent the intense burn of supremely spicy foods.

What’s the point?

Besides maybe a good sweat, what can you gain from shoveling down capsaicin-rich chilies? The easiest explanation, though not a scientific one, is for their taste. Peppers such as the habanero or the jalapeño, for example, have long been used in Latin and Caribbean cuisines because of the distinct and unmatchable flavors they impart on the foods to which they are added. Scientifically speaking, the spicy significance of capsaicin has evolved from the chemistry of taste to hot-topic applications in medicine, such as a capsaicin-enriched cream used by arthritis patients to relieve pain. Whatever your motivation, get it while it's hot.