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The Science of Hot Chiles

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By David Joachim and Andrew Schloss
From Fine Cooking #130, pp. 28-29

Hot chiles are integral to cuisines the world over, from Indian, Thai, and Chinese to Spanish and Hungarian. But 500 years ago, they were unknown outside of the Americas. The spicy pods originated in the New World-in Mexico, by most accounts-and traveled around the globe via Spanish and Portuguese traders. Legend has it that when Christopher Columbus tried one for the first time, he was reminded of the spicy heat of the black peppercorns he knew from Europe, which is why he called New World chiles peppers (even though they’re not related to peppercorns of any variety). Whether you call them chiles or peppers, here’s a look at what makes them so beloved.

Get the recipe: Sriracha Sauce

Why do chiles taste hot?
Capsicum chiles get their heat from a pungent oil called capsaicin (kap-SAY-i-sin). There are thousands of varieties of chiles, and the amount of capsaicin in each depends on the chile’s genetics, its growing environment (hot, dry conditions increase capsaicin), and its ripeness. Capsaicin concentrates in the placenta of the chile, the white ribs that anchor the seeds; from there, it migrates into the seeds and along the inner walls of the chile, where it’s found in lesser amounts.

The amount of capsaicin in a chile is expressed in Scoville units, a measurement invented around 1912 by Wilbur Scoville, a chemist working for the Parke-Davis pharmaceutical company. Sweet bell peppers, which have no capsaicin, measure 0 on the Scoville scale, and pure capsaicin measures 16 million units. Hot chiles, like habanero and Scotch bonnet, typically have between 100,000 and 350,000 units. Mild chiles, like Anaheim and New Mexico, range from 500 to 2500 units. Carolina Reapers, the current Guinness record holder for the world’s hottest chile, clock in at 1.5 to 2.2 million units.

Why do we like them?
Capsaicin oil is so irritating that one would expect it to be shunned by anyone who wanted to avoid pain. Yet the worldwide consumption of hot capsicum peppers compared to milder, more aromatic black peppercorns is 20 to 1. Why? It’s possible that the sensation of pain from chiles causes the brain to release pain-relieving chemicals that remain in our system after the sensation from the chiles has passed, leaving us with an enlivened palate and a mild sense of euphoria.

Is there a way to tame their heat?
You can manipulate the amount of heat by cutting away all or part of the chile’s ribs, which hold most of the capsaicin. If you’re cooking with chiles, know that the longer they cook, the more they break down and release their capsaicin, which will permeate the dish, but with continued cooking, the capsaicin dissipates. Therefore, to reduce spiciness, cook chiles only briefly, or for several hours.

If your mouth is already on fire, you can cool the burn with something cold that also contains dairy fat, such as ice cream or cold milk. These have a double cooling effect: The low temperature tricks your senses and cools the burning sensation, much like applying ice to an actual burn, while a dairy protein called casein helps dissolve the capsaicin, washing it away like soap washes away grease. Dairy will tame the heat in cooked dishes, too, so if your curry is too hot, stir in some cream or yogurt to tone it down.

Any tips for handling chiles?
Capsaicin is released when both fresh and dried chiles are cut or chopped, so avoid touching the cut part. You can wear gloves, or simply hold the chile by its stem and use tongs or other utensils to avoid contact with your skin. Capsaicin oil isn’t water soluble, so washing your hands doesn’t do much good, though using a scrubbing brush and a grease-cutting detergent like Dawn will help. If you’re puréeing fresh chiles that are high in capsaicin, ventilate the room and wear goggles to avoid burning your eyes. Capsaicin is volatile and goes airborne whenever it is released from the pepper’s cells.

Besides heat, what else do they bring to a dish?
Fresh green chiles have a mildly bitter taste and green grassy aromas. When they ripen from green to red, orange, yellow, or purple, these characteristics diminish, giving way to a mild sweetness and fruity, floral aromas (esters) typical of other ripe fruits. If you’d like grassy flavors in your salsa, use fresh green jalapeños; for more fruitiness, try ripe ones.

Dried chiles have even more flavor. Drying a chile evaporates its water content and concentrates its flavor compounds, creating the earthy aromas typical of dried fruits. If chiles are dried with smoke, as when fresh jalapeños are smoke-dried into chipotles, they’ll get another a layer of flavor. (Smokiness can also be added to fresh chiles by charring them.)

To develop flavor further still, cooks often toast dried chiles, a common first step for many classic chile sauces. Step number two is to rehydrate the toasted chiles in boiling water (or other liquid) before puréeing, which wakes up their flavor. Cooking dried chiles in braises and stews achieves the same goal.

Chiles can also influence texture. When they’re puréed, both fresh and dried chiles release pectin, a gluey type of fiber, which helps to thicken liquids. We can thank pectin, in part, for the smooth, creamy texture of Mexican chile sauces such as mole poblano.

Can I substitute fresh chiles for dried?
Because fresh and dried chiles are often used so differently in cooking, swapping one for the other usually doesn’t work. But in a pinch, if you want to substitute for heat level, you can replace a fresh chile, such as cayenne, with its dried ground version by using a ratio of 4:1 or 2:1. In other words, replace 1 teaspoon of minced fresh cayenne with 1/4 to 1/2 teaspoon of dried ground cayenne.

Drawing by Simone Shin, photo by Scott Phillips


Leave a Comment


  • 15190707 | 04/18/2015

    With reference to the comment of the possibility that the sensation of pain from chiles release pain- relieving chemicals... Could it be compared to the effect chocolate has on the brain, releasing endorphins to make us feel happy? Chiles just with a different effect?

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