DALLAS — Love hot peppers?

My co-worker Mateo does. And he’s been wondering something about the markings you can find on the outside of a jalapeño.

“Do these stretch marks actually indicate that they're hotter?” he asked.

“Who knew that was thing?” I said. 

“My mother-in-law says so,” Mateo said.

To figure this one out, I'm looking at agricultural research papers and talking to Daniel Cunningham in a community garden at Temple Emmanu-El in Dallas. He’s a horticulturist with Texas A&M AgriLife Research.       

“What do those cracks indicate?” I asked Cunningham.

“Really, they just indicate that outside skin, that exocarp, has split," he said. "Really, that's just the pepper growing faster on the inside then the outside skin can keep up."

This study in the journal HortScience backs that up. It concludes "cracks are a sign of maturity."

So older peppers tend to crack. And Daniel says older peppers are also hotter peppers. 

A paper in the journal Plant Science also appears to back that up. The compound that makes peppers hot is called capsaicinoid. It found "higher capsaicinoid abundance tended to occur in older fruit."

“If these were all hot jalapeño peppers and you let some of them mature longer, what would happen?” I asked.

“Generally, the more mature peppers are going to be spicier," Cunningham said. "And if the more mature peppers are the ones that crack the most, then logically, we could assume that more of the cracked peppers would be spicier as well."

And then we did a little research of own by first eating a younger jalapeño.

“A little bit of heat coming off," Daniel said. "On the back end, it does get a little spicier. But mellow, even spicy."

Now for one with cracks.

“Oh, that's going to be hot,” I said immediately after taking a bite. 

“Thirty to 40% hotter,” I concluded as tears streamed down both of our faces.

So, the presence of stretch marks on peppers generally does mean hotter peppers.

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