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The Scoville Scale: How Spicy is Spicy?

Updated: Mar 7

Author: Renee Cao

Editor: Vincent Chang

Artist: Daelah Nicholas

When we eat spicy foods, polymodal nociceptors, sensory neurons activate in our mouths and noses. They are the same receptors that activate from extreme heat and cause our brain to feel like it is burning when we eat spicy foods. Once these heat-sensitive receptors activate, our brain responds as if we’re in danger; we start sweating, and our hearts beat faster.

There are three main compounds involved in spicy foods: capsaicin, piperine, and isothiocyanates. Capsaicinoids and piperine are made of large, heavy molecules called alkylamides and are found in chili peppers and black peppers. These molecules stay in our mouths, which is why we feel our mouths are burning off after eating something spicy. Isothiocyanates are smaller and lighter molecules found in foods such as mustard, horseradish, and wasabi. This molecule can float into our sinuses, which causes burning sensations in our noses.

To measure the spiciness of foods, the Scoville Scale is used. The scale is based on only capsaicinoids, which means that the Scoville Scale can not measure food like wasabi. The scale measures how much water and sugar are needed to dilute the effects of capsaicin found in peppers. A rating of 0 Scoville Heat Units (SHU) means a pepper is mildly spicy. The bell pepper has this rating. In comparison, Sriracha Hot Sauce has a 1,000-2,500 SHU, Tabasco Hot Sauce has a 2000-5000 SHU, jalapeno peppers have a 2500-8000 SHU, cayenne peppers have a 30,000-50,000 SHU, and ghost peppers have a 1,000,000 SHU. Some examples of the highest SHU include pepper spray with 2-5.3 million, the Carolina Reaper pepper with 1.56 million, and the Dragon’s Breath pepper with 2.48 million. However, it is important to note that this scale is not necessarily accurate, as everyone has a different spice tolerance, thus the effects of capsaicin will vary from one person to another. Today, the High-Performance Liquid Chromatography measures chili pepper heat, which measures a pepper’s heat-producing chemicals and is more standardized.



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Capsaicin, Piperine, and Zingerone in Rat Trigeminal Ganglion Cells.” Journal of

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“The Science of Spiciness - Rose Eveleth.” TED-Ed,

“The Scoville Scale.” Chili Pepper Madness, 18 June 2019,

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