Have Jalapeños Lost Their Heat?

Then there’s the instances when we buy jalapeños at a farmer’s market or grow them in a backyard garden, discovering that sometimes the chiles are scorchingly hot—but other times, they’re not.

What’s going on? 

As dining critic Brian Reinhart first reported in D magazine, the situation is not just due to happenstance, but rather, “a deliberate choice.” 

To get the story, I phoned  Stephanie Walker, Ph.D., extension vegetable specialist at New Mexico State University. She is also an advisory board member of the university’s Chile Pepper Institute and co-chair of the 2024 New Mexico Chile Pepper Conference. Prior to her academic career, Walker spent a decade working in the chile processing industry. Oh, and she eats chiles at  “nearly every meal.” If anyone could shed light on the situation, Walker could. 

It’s no secret that jalapeños, with their high-gloss, forest-green skin; bullet-shaped contours; and vegetal, citrusy flavor, are incredibly popular with home cooks. What you may not know is that only 20 percent of the crop, which the U.S. imports primarily from Mexico, is sold fresh in supermarkets. The majority of the peppers, Walker said, are purchased by processing plants for making jarred salsas and other finished products. 

It’s also important to know that it’s very difficult to accurately predict heat levels in any chile. That’s because genetics isn't the only factor that influences how much capsaicin—the chemical compound that gives the fruit its burn—a pepper produces. Environmental factors play a big role, too. Drought, heat, disease, insect pressure, and even wind can stress plants while they are maturing, increasing their capsaicin levels.  

And therein lies the problem: “If you're a processing plant, and you're trying to put together a [product] formulation that's ‘mild’ or ‘medium’ or ‘hot’,” Walker said, “you really need to know how hot the peppers that you're purchasing and bringing into the plant are going to be, so you can predict that final pungency.” 

To avoid mislabeling and/or letting their customers down, scrupulous processors began to demand jalapeños that served up characteristic jalapeño flavor but very little or no pungency. 

This way, they could ratchet up the heat of salsas and other products in a controlled fashion by adding oleoresin capsaicin, a highly concentrated, oily red extract from chiles that Walker dubbed “pure heat.” (Oleoresin capsaicin is also the active ingredient in pepper spray.) By adding the incendiary extract in small increments, she said, processors would be able to guarantee that products met precise heat specifications.

Knowing how crucial it was for processors to fine-tune packaged products, Walker said that beginning in the mid 1980s to mid 1990s, Big Agriculture set to work developing jalapeños that are bred to have less capsaicin but plenty of the chile’s signature fresh, grassy flavor. Texas A&M University, New Mexico State University, and major seed companies all began selective breeding programs. 

The results, she said, were some “amazingly productive” and extremely mellow jalapeño varieties, including the TAM II line, of which some specimens have registered a mere 1080 Scoville Heat Units, roughly the same as pasillas and poblanos. For comparison, one of the hottest jalapeño cultivars, the Grande, has been recorded at a searing 20,000 SHU. 

Fast forward to today, and, according to Walker, many of the more tepid jalapeño varieties have leaked onto the consumer market. Produced by major Mexican seed companies, they aren’t typically named or numbered, but they’re “beautiful, have large fruit, and are flavorful.” In other words, they’re perfect for supermarket shoppers who can’t tolerate heat, but a big disappointment to those who want to feel the burn. 

So what are heat-seeking cooks to do? Your best bet, Walker said, is to request pungent jalapeños from local farmers and pepper growers. You can also try your hand at growing heirloom chiles, which tend to be reliably hot. Two to look for, she said, are ‘Early Jalapeño’ and ‘Mitla’. It’s worth scanning seed catalogs, too, as some nurseries specify the average SHU for chiles. 

What’s the outlook for cooks who prefer jalapeños with big, spicy personalities? It’s bright, said Walker, because she and other chile breeders are—get this— “hot on the trail” of propagating new varieties that are not only pungent, but predictably so. 

Here is a collection of some of our favorite jalapeño recipes.