You Can Tell a Spicy Jalapeño From a Mild One Just by Looking at It

There are spicy peppers and then there are oh-my-goodness-someone-grab-the-milk-spicy peppers. And sometimes it can feel like a total crapshoot when it comes to predicting the spice level of a pepper before you slice into it. Are your happy hour spicy margaritas going to be mild, medium, or extra spicy today? On the flip side, there's nothing worse than going to make fresh salsa and discovering your jalapeño is as mild as a green bell pepper. It can feel like you're at the whim of a random decision in the produce aisle.

Leave it to social media to change that forever. Just like the blueberry picking tip that blew my mind a few weeks ago, this feels like a tip that will forever change the way I shop for peppers. More specifically, jalapeño peppers.

The video was posted by chef and frequent "Chopped" judge, Amanda Frietag, to Instagram over the weekend and instantly took off. And it's not hard to see why.

In it, Frietag claims you can tell a spicy from a mild jalapeño just by looking at it. She says the smooth, unblemished jalapeños are mild, while the ones with stitches and lines that resemble stretch marks are hot. She even does a taste test to prove it, and lo and behold the stretch-marked one is worthy of a "Hot Ones moment," according to Frietag.

How to Tell a Mild Jalapeño From a Hot One (Without Trying It)

Let's start with a little recap on what makes peppers hot in the first place. Capsaicin is the compound in chile peppers that creates spicy foods' signature burn. It's found throughout peppers, but most concentrated in the area surrounding the seeds. The more capsaicin in a pepper, the hotter it will taste on the tongue. But without tasting it, how could you know how hot a specific pepper will be?

You may think of teenage growth spurts when you hear "stretch marks" but they happen to produce, too—and for a similar reason. As pepper plants grow and age, they encounter several environmental factors that put stress on the plant like water and sunlight levels, as well as temperature fluctuations. These environmental stressors result in marks, lines, or flecks on the fruit (the peppers themselves).

It's still debated, but the leading theory is that stressed plants result in higher concentrations of capsaicin in the peppers, and therefore more fiery produce. So the thinking goes, the older the plant and the more stress it's been under in its lifetime, the spicier its peppers will be.

The easiest way to tell if the peppers in your grocery store are from younger or more mature plants is to look for those telltale lighter stretch marks. The more white lines and marks you see, the hotter the pepper will likely be. The smoother and shinier the pepper, the younger and therefore, milder it will likely taste.

We tried it for ourselves, picking up two jalapeños from our local grocery store; One with marks, one smooth. Lo and behold, upon first bite the difference was immediately clear. And the theory proved correct. The smooth one tasted no spicier than a green pepper, while the one with stretch marks was "spicy AF," as Frietag put it.

Although it worked for us, this method isn't 100% foolproof. Here's why.

Several Factors Determine How Spicy A Pepper Will Be

As one commenter on Frietag's post pointed out, there are several factors that impact the capsaicin levels, and therefore spice level, of a pepper.

"Capsaicin production is more determined by climate, soil type, amount of moisture throughout the growing season, and how long the peppers have been on the plant (there’s a sweet spot for extra spicy jalapeños, just before they start ripening to red when they get milder again)," commented @soil.to.sky.farm on Instagram.

While you can't believe everything you read on social media, this is true. A 2014 study found that "the temperature at which chili peppers are grown, the position of the fruit on the plant, age of the plant and light intensity are all factors affecting the total amount of capsaicin in a given chili pepper variety."

Another commenter on Frietag's video confirmed that this test isn't accurate 100% of the time.

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

So, while it may be reliable a majority of the time, maybe don't be as bold as we were and bite directly into a jalapeño just by the looks of it. A pepper's appearance may be a good indication of what spice lies inside, but the best way to tell if it will be spicy or not is still by relying on another one of your five senses: taste.