Jennifer Schultz Nelson
Extension Educator, Horticulture
Language is a funny thing. Mention chile peppers, and many people assume you are talking about some burning hot pepper that only a mouth made of steel can tolerate. Technically speaking, the term "chile" includes all the fruits we call peppers, even those that are not considered "hot", like bell and banana peppers.
Apparently the confusion stems from Christopher Columbus, who assumed that chiles he observed in the New World were related to the true pepper plants that produce peppercorns. What we call peppers are not related to true pepper plants, but they are a member of the Solanaceae family, whose members include tomatoes and potatoes.
People have strange reactions where peppers are concerned. My dad refuses to eat any dish made with green bell peppers, insisting that they bother his stomach even if he picks them out. Other people can't get enough peppers–the hotter the better. I recall a show on the Food Network where two pepper lovers challenged each other to see who could eat the hotter pepper. Of course, these were two men. My humble opinion is that men will turn anything under the sun into a competition, and I don't know any women that would voluntarily submit to what ended up being a very painful contest. In the end, the winner's face was beet red and tears streamed from his eyes. He seemed pretty proud of himself afterwards, but my reaction was to change the channel.
The chemical culprit inflicting all this pain is called capsaicin. It is part of a larger group of alkaloid compounds called the capsaicinoids. Peppers produce several different capsaicinoids, but capsaicin is produced far more than any other. It is primarily present in the membranes inside the pepper, not the seeds as many people believe. The seeds may absorb some capsaicin from this membrane during development, but they don't produce it themselves.
Capsaicin is also part of a chemical class called vanilloids, which includes vanillin, the chemical that is what we taste as "vanilla". Other familiar compounds in this group are eugenol, which contributes flavor to bay leaves, allspice and cloves, and zingerone, which adds pungency to ginger and mustard.
While not an absolute, different kinds of peppers produce different amounts of capsaicin. In 1912, Wilbur Scoville developed a scale to measure the heat in different chiles. The Scoville Scale ranges from zero to well over 300,000 Scoville units. The more Scoville units a pepper has, the hotter it is.
The scale was developed by having a taste panel sip solutions containing increasingly dilute solutions of a particular pepper until they stated that the solution no longer burned their mouth. Based on the number of dilutions needed to get to this tolerable state, a value in Scoville units could be assigned to that type of pepper. Since nothing in nature is exactly the same every time, ranges of Scoville units are typically given for each type of pepper.
It is not surprising that we call some peppers "hot" considering how capsaicin behaves in the human body. It binds to receptors in the mouth that are the same receptors that register pain from heat, so we say that some peppers make our mouth burn. Repeatedly exposing these receptors to capsaicin depletes their capacity to react, in effect helping a person develop a tolerance of hotter and hotter peppers.
In high enough amounts, the heat from capsaicin can be incapacitating. Ancient Mayans used hot peppers in battle to slow their enemies, in the same way that pepper sprays do today. Some peppers have enough capsaicin to cause painful blistering of the skin. Pharmacists have taken advantage of this heat in creating creams for arthritis pain and sore muscles that use just enough capsaicin to produce a warm feeling on the skin, rather than pain.
Many pepper lovers report feeling great after the initial painful heat of a pepper. This is believed to be due to a release of endorphins, the human body's natural painkillers, which are triggered in a complex chain reaction after the pain receptors in the mouth react to the capsaicin. This is the same feeling that some athletes have called the "runner's high". Some researchers have linked the release of endorphins to general wellness and disease prevention, but more research is needed to solidify this claim.
Capsaicin does not exist merely for humanity's culinary enjoyment. In a way it is a defense chemical for the plant, helping to insure the future of their species. The key to this defense lies in the fact that capsaicin can only be tasted by mammals, since they have the proper receptors to detect it. Birds lack this receptor entirely. Also, if mammals eat peppers, the seeds are destroyed within their digestive tract. On the contrary, when birds consume peppers, the seeds pass through their digestive tract undisturbed, and typically get "distributed" far from the original plant. Scientists propose that capsaicin evolved as a means to discourage mammal's consumption of peppers, which would potentially destroy future pepper generations.
Typically if you eat a pepper that is too hot for your taste, the first thing you reach for is a glass of water. What you should really be reaching for is a glass of milk or some other dairy product. Dairy products contain a protein called casein, which acts like a detergent on capsaicin. It coats the capsaicin molecules and strips them from the receptors in your mouth, alleviating the burning sensation. New Mexico State University, a leading authority on chile peppers, actually recommends that if your hands are burning from contact with peppers, you should swab the area with rubbing alcohol, then soak it in milk. You can avoid burning your fingers altogether by remembering to wear gloves when handling chile peppers.