How is spiciness defined and measured in scientific terms?

Author: Alicia Ma and Calista Yoo

Editors: Emily Chen and He-Hanson Xuan

Artist: Serena Yung

Sweat and tears drip down your face as you frantically try to gulp down a cup of water. No, this reaction isn’t from the blistering heat of the hot summer sun. It’s from the sweltering heat of the Carolina Reaper pepper you just bit into Ranked the spiciest pepper in the world, the Carolina Reaper measures 2 2 million SHUs

But what exactly is a SHU? From sweet chili peppers to fiery ghost chili peppers, peppers have a wide range of spiciness. But exactly how spicy or wide is this range? To answer this burning question, the Scoville Scale is a scale that was invented to measure the spiciness of peppers in Scoville Heat Units (SHUs) The scale was created by Wilbur Scoville in 1912 in an attempt to find the right pepper for a heat-producing ointment .

The spice in peppers comes from the chemical compound Capsaicin. It is the culprit of the burn you feel on your tongue and the sweat dripping down your face after you eat a spicy pepper

To measure the spiciness of a pepper in SHUs, an alcohol extract of capsaicin from a dried pepper is diluted with a solution of sugar water until its spicy flavor can no longer be tested. From there, it is assigned SHUs based on how much water and sugar are needed to dilute it to remove its fiery flavor. If a pepper has an SHU of 5000, that means it required 5000 dilutions before the piquant flavor was deemed undetectable by taste buds

But exactly how accurate is this measurement? The Scoville test relies on human taste to determine whether a diluted