Life's Little Mysteries

Why Do Chili Peppers Taste Hot?

chili peppers, pepper, capsaicinoids, endorphins, food, hot
An odorless, flavorless substance in peppers makes them hot. (Image credit: Nenovbrothers |

The culprit of the burning feeling you get from jalapeno-loaded Mexican food: chemical compounds called capsaicinoids. The odorless, flavorless substances are hidden in the white flesh inside of peppers. And when you pop a pepper into your mouth, the chemical binds to receptors that respond to pain from heat in the mouth and throat.

The brain gets the message and sends out the body’s “fire squad” to remove the hot substance, resulting in increased circulation (boosts metabolism), cooling perspiration and typical reactions to any irritant (runny nose and teary eyes).

The pain also leads to a release of endorphins, the body’s natural painkillers, which flood the diner with blissful feelings.

So those tears are actually tears of joy.

Not all peppers pack the same punch. In 1912, chemist Wilbur Scoville developed a measure of the “hotness” of a chili pepper called the Scoville Organoleptic Test. A pepper’s pungency is measured in multiples of 100 units and refers to how much sugar-water was needed to dilute the pepper to a point where the tasters could no longer taste (feel) the heat.

Some examples include:

  • Sweet bell pepper — 0 units
  • Jalapeno — 2,500 to about 8,000 units
  • Cayenne — 30,000 to about 50,000 units
  • Red Savina Habanero — 350,000 to about 577,000 units

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Jeanna Bryner
Live Science Editor-in-Chief

Jeanna served as editor-in-chief of Live Science. Previously, she was an assistant editor at Scholastic's Science World magazine. Jeanna has an English degree from Salisbury University, a master's degree in biogeochemistry and environmental sciences from the University of Maryland, and a graduate science journalism degree from New York University. She has worked as a biologist in Florida, where she monitored wetlands and did field surveys for endangered species. She also received an ocean sciences journalism fellowship from Woods Hole Oceanographic Institution.