You Can Distinguish a Spicy Jalapeño from a Mild One Just by Looking at It

There are hot peppers, and then there are 'call-the-fire-department' hot peppers. Predicting the heat level of a pepper before slicing it open can sometimes feel like a gamble. Will your happy hour spicy margaritas be mild, medium, or fiery? On the other hand, there's nothing worse than prepping fresh salsa only to find your jalapeño is as bland as a bell pepper. It's like leaving your spice destiny to chance when picking produce.

Thanks to social media, this unpredictability is a thing of the past. Much like the game-changing blueberry picking hack that recently went viral, this new jalapeño tip will forever change the way I shop for peppers.

The video, posted by celebrity chef and 'Chopped' judge Amanda Frietag on Instagram, quickly went viral over the weekend. And it's easy to see why.

In the video, Frietag demonstrates that you can differentiate a spicy jalapeño from a mild one by simply looking at it. She explains that smooth, blemish-free peppers are mild, while those with lines and markings resembling stretch marks are much hotter. She even performs a taste test, and sure enough, the 'stretch-marked' pepper proves to be worthy of a true 'Hot Ones' challenge, according to Frietag.

How to Differentiate a Mild Jalapeño from a Hot One (Without Tasting It)

Let's begin by revisiting what makes peppers spicy in the first place. Capsaicin, the compound responsible for the signature burn of spicy foods, is found in chile peppers. While it's spread throughout the pepper, the highest concentration is found around the seeds. The more capsaicin, the hotter the pepper will feel on your tongue. But without tasting it, how can you tell how spicy a pepper actually is?

You might think of stretch marks as something that happens during a teenager's growth spurt, but peppers can develop them too—and for similar reasons. As pepper plants mature, they face various environmental stressors like fluctuating sunlight, water, and temperature. These stress factors cause visible marks, lines, or spots to appear on the fruit (the peppers).

While still a topic of debate, the most widely accepted theory is that stressed plants produce peppers with higher levels of capsaicin, making them spicier. In short, the more stressed and mature the plant, the hotter its peppers will likely be.

A simple way to spot whether the peppers at your grocery store come from younger or older plants is by looking for those distinct white stretch marks. The more white lines or marks you see, the spicier the pepper is likely to be. On the other hand, a smooth and glossy pepper typically comes from a younger plant and will probably be milder in flavor.

We decided to test the theory ourselves, grabbing two jalapeños from our local grocery store—one with marks and one without. After taking a bite, the difference was immediately obvious. The smooth one tasted as mild as a green bell pepper, while the one with stretch marks was 'spicy AF,' just as Frietag had described.

While the method worked for us, it’s not foolproof. Here’s why.

Several Factors Influence a Pepper's Spice Level

As one commenter on Frietag's post pointed out, many factors influence the capsaicin content—and thus the spiciness—of a pepper.

"Capsaicin levels are more affected by climate, soil type, moisture levels during the growing season, and how long the peppers stay on the plant (there's a sweet spot just before they ripen to red, when they’re at their hottest)," commented @soil.to.sky.farm on Instagram.

Although you can't always trust everything on social media, this is actually accurate. A 2014 study found that factors like the temperature in which chili peppers are grown, the fruit's position on the plant, the plant’s age, and light intensity all impact how much capsaicin a pepper contains.

Another commenter on Frietag’s video added that this test isn’t foolproof.

"I got a perfectly smooth one that barely had a scent, and it turned out to be really hot," they wrote.

While this method may work most of the time, maybe don’t go as far as we did by biting into a jalapeño based solely on its appearance. A pepper's look can give you a hint about its heat level, but the most reliable way to know if it's spicy is still by using your fifth sense: taste.