Unless you live in England or Ireland or any one of those countries where the only spices are salt and pepper, you’ve probably tried your fair share of hot sauces and hot peppers. Some of these sauces and peppers have a healthy level of spice, while others are so hot that they make you sweat liquid fire and wish you’d never been born. Of course, we can tell when one food is spicier than another food just by tasting it. But until Wilbur Scoville, an American pharmacist, came along, there was no way to objectively compare how spicy one thing was in relation to something else.
If you’ve ever watched the hit YouTube series Hot Ones, in which Sean Evans interviews celebrities such as Ed Sheeran, Quavo, Pete Davidson, and Drew Barrymore while they sample scorching hot chicken wings, then you’re probably already familiar with the Scoville scale. The scale, which is named after its inventor, however, isn’t just based on someone trying a pepper and saying, “Woah, that’s hot!” There are actually several different methods that have been used to measure the spiciness of peppers, many of them far more scientific than you might think.
Since the Scoville scale was invented, it has served as a warning for those who know their spice limits and a challenge for those who want to push their limits of capsaicin tolerance. However, I think we can all thank Wilbur Scoville and all the scientists who have continued to develop the Scoville for letting us know exactly what we’re getting ourselves into when we bite into a hot pepper. Let’s take a look at how the Scoville scale works and how it came to be.
The Scoville Scale
The Scoville scale is a way of measuring the pungency (or spiciness) of a chili pepper. It is measured in Scoville Heat Units, or SHU, with the peppers with the highest SHU reading being the spiciest. On a basic level, the SHU of a given pepper is based on the concentration of capsaicinoids in the pepper, which are compounds in which capsaicin (the stuff that makes peppers spicy) are the main component. Peppers are rated on multiples of 100 SHU.
The method that was first used to measure the SHU of a pepper was invented by Scoville himself and is called the Scoville organoleptic test. This test involves taking a specific weight of dried peppers and dissolving them in alcohol, which extracts the capsaicinoids. This alcohol-pepper mixture is then diluted in a solution of water and sugar. Five trained panel members (presumably people with high spice tolerances and experience with eating spicy foods) are assembled to test the pepper. The alcohol-pepper mixture is then mixed into the water-sugar solution in decreasing concentrations until at least three of the panel members can no longer taste the spiciness. Essentially, you should be able to taste really small concentrations of really hot peppers, while you’ll need a fairly large concentration if the pepper isn’t that spicy.
Unfortunately, the Scoville organoleptic test was not quite as accurate as heat-lovers wanted it to be. Since human subjectivity comes into play and the number of spice receptors in people’s mouths vary so widely, the Scoville organoleptic test was decidedly not the best method for creating an objective scale of spiciness.
So, since the 1980s, a different method has been used to quantify the spice heat of peppers. This method, called high-performance liquid chromatography (HPLC), involves actually separating out the capsaicinoids in a pepper. Essentially, the pepper is pumped through an absorbent material, and since the capsaicinoids have different properties from the other components of the pepper, they flow through the absorbent material at a different rate and are separated. This gives scientists a way to measure with great accuracy the concentration of capsaicin in a pepper, which they can then convert to a number of Scoville units.
While Scoville’s organoleptic test is no longer used to measure SHU for the most part, the universal scale of spiciness still bears his name. And while many of us have heard of the Scoville scale in relation to the hot sauces we put on our chicken wings or lasagna or beef stroganoff, the reason for the invention of the Scoville scale really doesn’t have anything to do with food.
The Wilbur Scoville Story
Wilbur Scoville was born on January 22, 1865, in Bridgeport, Connecticut. On September 1, 1891, he married Cora B. Upham and the two of them went on to have two daughters, Amy Augusta and Ruth Upham. During his life, Scoville worked as a pharmacist, a profession that has pretty much nothing to do with food.
While he was alive, Scoville was probably most well known for the textbook he published in 1895 The Art of Compounding, which has gone through at least eight editions and was used for reference well into the 1960s. The Art of Compounding is also one of the first known sources that makes reference to milk as an antidote for pepper spice. So, while Scoville’s job may not have directly involved chili peppers at the time, it’s clear that he had some sort of love/fascination with them.
For a while, Scoville worked as a professor at the Massachusetts College of Pharmacy and Health Sciences. Later, however, he got a job at a pharmaceutical company called Parke-Davis, which is where he came up with the Scoville scale.
As the story goes, Scoville was working on Parke-Davis’s painkilling cream, known as Heet liniment, in which the active ingredient was capsaicin. Just as capsaicin can numb your tongue when you dump too much hot sauce on your meal, so can it numb your muscles when applied to your skin. To get capsaicin into their cream, they had to extract it from peppers. And because HPLC was not being widely used back then, there was no good way to determine how much capsaicin was present in different kinds of peppers, which made it very difficult to control the dosage of capsaicin in each batch of Heet liniment.
Then, along came Wilbur Scoville, who devised the Scoville organoleptic test to measure capsaicin concentrations with impressive accuracy. And while the test itself proved pretty effective, Parke-Davis never actually found a way to effectively use capsaicin as a painkilling agent. While Heet liniment is still on the market today and still contains capsaicin, the primary active ingredient is salicylate methyl, a compound derived from wintergreen.
Nonetheless, we still use the Scoville scale to measure the spiciness of the chili peppers we use for our food. And while that may not have been Scoville’s intention, I’d say it’s a pretty amazing side-effect. Scoville died in 1942 at the age of 77. But if he were alive today, he’d probably be thrilled to see his scale being prominently featured on one of the most popular series on YouTube, Hot Ones.
Scoville Rating Examples
In the interest of gaining a better understanding of what Scoville ratings correspond with what level of spiciness, here are some of the Scoville ratings of foods, sauces, and other items that everyone has heard of:
- Bell Pepper (0 SHU)
- Shishit Pepper (50-200 SHU)
- Cholula Hot Sauce (500-1,000 SHU)
- Texas Pete Hot Sauce (747 SHU)
- Ancho Pepper (1,000-2,000 SHU)
- Crystal Hot Sauce (2,000-4,000 SHU)
- Tabasco Hot Sauce (2,000-5,000 SHU)
- Huy Fong Sriracha Hot Sauce (2,200 SHU)
- Tapatio Hot Sauce (3,000 SHU)
- Thai Chili Pepper (50,000-100,000 SHU)
- Scotch Bonnet Pepper (100,000-350,000 SHU)
- Carolina Reaper Chili Pepper (2,200,000 SHU)