How is the spiciness of those notoriously spicy peppers measured?

© National Institute of Standards and Technology

Leviathan Press:

As a person who can hardly eat spicy food, my life naturally lacks the pleasure of "benign self-abuse". However, I have always been curious. Although we are eating the same kind of pepper, some people are sweating profusely, while others are calm as usual. So, how is the so-called pepper spiciness rating determined?

Plus, when you eat peppers, receptors in your mouth send pain signals to your brain in the form of burning or heat, so your brain produces endorphins to block the pain. Of course, extremely hot peppers do more than just numb your mouth. After consuming these super-hot peppers, your body develops fluid-filled "blisters" in areas that come into contact with concentrated capsaicin, including your mouth and throat. These blisters help absorb the capsaicin's heat. But some peppers, like Dragon's Breath, are so hot that blisters alone can't stop the heat—the capsaicin seeps into the blisters and continues to activate receptors on nerve endings beneath them, causing a painful burning sensation that lasts for at least 20 minutes.

The Journal of Emergency Medicine reported on the tragic situation of a 47-year-old California man who ate a burger containing ghost peppers: violent vomiting, which eventually led to a ruptured esophagus (a risk of death) and required medical treatment. In some cases, eating chili peppers can cause anaphylactic shock, severe burns, and even airway closure, which can be fatal if not treated in time.

So, the enjoyment of eating spicy food...still needs to be within a certain limit.

In September 2013, food critic Matt Gross sat down at the second annual Hot Sauce Expo in New York City, ready to take on a daunting challenge. On the table in front of him were three small, deep red, shrunken peppers, and he needed to eat them as quickly as possible. Gross is an experienced "hot pepper fan". He completed the challenge with ease, eating all three peppers in a little over 21 seconds. At first, the peppers seemed to have no effect, but after about a minute, the spicy taste finally began to show:

"Sweat started to form under my eyes, then on my forehead. A burning sensation began - not in my mouth, but in my throat, like a fiery tide flowing through me. I jumped a little, danced a little, waved to everyone, wiped my brow dramatically.

But it was a pain I could handle, a pain I could savor. I could get through it—all I had to do was wait. Literally, it was only five or six minutes, and then the spiciness peaked, the pain and swelling began to subside, and the endorphin rush began. I felt great. No, awesome! I had so much energy and I was talking to everyone I could find.”

Yet this endorphin rush—what Chili fans call the “Runner’s High”—comes at a high price. As Gross later recalled on his way home from the fair:

"Around 5:30 p.m., I began to notice a burning sensation just below my breastbone. I wondered: Why did it take so long to start? Slowly, the burning worsened, but I still didn’t pay it any attention… But then, as I walked down to Penn Station to catch the subway back to Brooklyn, it got worse. My breath was hyperventilating. I hunched over, taking small steps through the station. Eventually, I had to stop and sit on the steps. To my right was a homeless man in the same pain as me. To my left, too. The smell was not good. Yet I just wanted to curl up and wait it out… It was like a hot nickel ball was implanted above my stomach—it again made me want to stop and lie down on the rain-soaked sidewalk until the pain went away."

Carolina Reaper pepper. © Wikipedia

Gross had just experienced the fiery fury of the Carolina Reaper, which, at 2 million Scoville Units, is certified by the Guinness Book of World Records as the world's hottest pepper. But what exactly is the Scoville scale? How is the heat of a pepper measured? And what causes that burning sensation? Let's enter the fiery and fascinating world of peppers.

What we commonly call "peppers" are the fruits of the Capsicum plant, native to the Americas but now cultivated all over the world. The compound that gives peppers their spicy taste is 8-methyl-N-vanillyl-6-nonenamide, more commonly known as capsaicin.

Each part of the chili pod has a different amount of capsaicin. © Birdhouse Chillies

Capsaicin is a white waxy solid in its pure state. It is a powerful tissue irritant and mild neurotoxin that directly stimulates the TPRV1 pain receptor channel in mammals. This means that the spicy feeling is not actually a taste, but a pain. This also means that hardcore chili fans are actually a kind of self-abuse. Capsaicin is so potent that even a small amount can overload nerve endings and even cause numbness, so this compound is often used as a local analgesic to treat muscle pain, arthritis and other minor pains.

Illustration from the Códice Mendoza showing a child being held over a burning chili fire. The child's eyes are watering. Perhaps this was a punishment for some bad behavior. © Birdhouse Chillies

Capsicum plants evolved capsaicin to prevent mammals from eating their fruits, as herbivorous mammals usually chew and destroy the seeds before they pass through their digestive systems. The seeds of peppers are mainly spread by birds, whose nervous systems are not affected by capsaicin. Although pepper plants have been cultivated and eaten for centuries, it was not until 1912 that American pharmacist Wilbur Scoville developed a method to quantitatively measure the heat of the pepper.

Although Scoville is remembered today for his spiciness scale, during his lifetime he was best known for his 1895 book, The Art of Compounding, which remained a standard textbook in pharmacy until the 1960s. In 1912, Scoville was hired by Detroit pharmaceutical giant Parke-Davis, which was developing a capsaicin-based topical pain relief ointment. To determine the dose of capsaicin needed for the ointment, Scoville first developed a spiciness scale and established an experimental method to measure the spiciness of different peppers. In this method, the "Scooville Organoleptic Test," peppers were dried, ground into a fine powder, and mixed into a solution of alcohol, water, and sugar. This mixture was then distributed to five tasters.

Since the perceived spiciness of any particular food varies greatly from person to person, the panel can come up with an average. The chili solution is then diluted with water and redistributed to the tasters until none of the tasters can detect any spiciness. The number of dilutions required becomes the chili's spiciness, or Scoville Heat Units (SHU). For example, if a saturated chili solution must be diluted 50,000 times before the tasters can no longer detect the spiciness, the chili is rated at 50,000 SHU.

Savina chili peppers. © Chili Craze

To make it clearer how the scale works, a bell pepper without capsaicin has a SHU rating of 0, while a regular jalapeno has a SHU rating of 3,500-8,000. Scotch bonnet and Red Savina peppers have a SHU rating of 580,000, while police pepper spray and the Carolina Reaper have a SHU rating of 1.5-2 million. Pure capsaicin has a SHU rating of 16 million. However, Parker-Davis never succeeded in using capsaicin for topical analgesia, and although the company's ointment is still sold today, its active ingredient is methyl salicylate, not capsaicin.

Although the Scoville scale is still in use today, its method of measuring heat is no longer used. The main flaw of the Scoville organoleptic test is that it relies on human perception, which is extremely subjective and varies based on a variety of factors, including age, the number of pain receptors in the mouth, personal taste preferences, and experience with spicy foods. Sensory fatigue can also affect test results, causing tasters to become less sensitive over time. As a result, the heat ratings of the same pepper can vary by as much as 50% between different labs.

© ActiveCare Physical Therapy

So, since the 1980s, high-performance liquid chromatography (HPLC) has been used to determine the precise capsaicin content of different peppers. This method yields what the American Spice Trade Association calls “pungency units”—equivalent to one part of capsaicin per million parts of dried chili peppers. These units can be easily converted to Scoville heat units by multiplying by 16. But while this method is more precise than the old sensory test, measuring heat is still not an exact science. The intensity of the heat of the same pepper can vary greatly depending on factors such as the seed and growing conditions, while the heat of a sauce made from a certain pepper depends on its moisture content. So the Scoville rating for a particular pepper variety is based on the average of multiple samples, while the heat of a sauce is adjusted based on the so-called “D value,” defined as the total mass of the sauce divided by the mass of its dried chili component.

© Tenor

In fact, even peppers of the same variety can vary widely in their heat, which is why the Carolina Reaper still holds the Guinness World Record, even though several ostensibly hotter peppers have been bred since then. For many years, the world's hottest pepper was the 577,000 SHU Savina Red, discovered by Frank Garcia of GNS Spices in Walnut, California. In 2007, however, the Savina Red was surpassed by the Indian Ghost pepper, grown at New Mexico State University, which has a heat rating of 1,001,304 SHU. But even that pepper was surpassed in 2011 by the Carolina Reaper, bred by Ed Currie of Puckerbutt Peppers in Fort Mill, South Carolina. The Carolina Reaper is a cross between the Naga Viper and the Caribbean Red Habanero, and is officially certified at 2 million SHU.

Curry with his Carolina Reaper peppers. © Need The Heat

Pepper X. © Sonoran Spice

Since then, Currie has bred a new pepper called "Pepper X", which he claims has a spiciness of 3.18 million SHU, but unfortunately, the spiciness of each individual pepper varies so much that the average spiciness is lower than that of the Carolina Reaper.

"Dragon's Breath" chili pepper. © Live Science

Similarly, the Dragon's Breath, bred by British pepper grower Neal Price and Nottingham Trent University, was measured at 248 million SHU, but failed to dethrone the Carolina Reaper due to its high variability. Although the Scoville heat scale was originally developed to measure the effects of capsaicin, other plant compounds can stimulate the same pain receptors. These include piperine, the active ingredient in black pepper, and gingerol, which is found in ginger and has a spiciness rating of 100,000 SHU and 60,000 SHU, respectively.

Euphorbia resinosa, also known as white-horned Euphorbia cerasifera, is a species of Euphorbia native to Morocco. © Wikipedia

The most potent non-capsaicinoid compounds to date are resiniferatoxin (RTX) and tinyatoxin (TTX), which are found in the cactus-like plants Euphorbia resinifera and Euphorbia poissonii in northern Nigeria. These substances stimulate the same TPRV1 neural pathway as capsaicin, but they are 1,000 times more potent than capsaicin, meaning that in their pure form they would have an incredible Scoville heat rating of 16 billion SHU. Thankfully, these toxins aren’t added to any hot sauces, though people in northern Nigeria use them as natural insecticides. Furthermore, because RTX and TTX are able to selectively target pain receptors without affecting other nerve cells, these compounds are currently being studied as potential treatments for chronic pain. All of this brings us to an important question: Since capsaicin is a neurotoxin, can eating too many hot peppers really kill you?

© JustWatch

The answer is yes. In 1980, researchers at Mahidol University in Thailand deduced from experiments on mice that about 170 grams of pure capsaicin was enough to kill a 68-kilogram adult. Deaths in these experiments were caused by a strong inflammatory response triggered by capsaicin, which caused the subjects' blood vessels to dilate generally and their blood pressure to drop sharply. However, to ingest so much capsaicin, you would need to eat 1.4 kilograms of dried Carolina Reaper chili powder at a time - a difficult test that is almost impossible for ordinary people to endure...

By Gilles Messier

Translated by gross

Proofreading/Rabbit's Light Footsteps

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