Sweet potato that’s sunken on the outside and has odd circles on the inside

What you see: Orange and white circles inside your sweet potato. Parts of the outside may be wrinkly and sunken; the sweet potato doesn’t seem like it’s rotting, but also doesn’t seem right. 
What it is: A very dried out sweet potato; it’s seen some things. 
Eat or toss: It’s not unsafe; but probably won’t taste good. 

Holy, wacky sweet potato, Batman, this is a weird one, right? But straight from reader Elana G.’s kitchen to your screen, here’s a sweet potato that’s not technically unsafe to eat, but probably won’t taste very good. This sweet potato’s been through something and has shed A LOT of water on the way. 

“This potato is severely dehydrated from being stored improperly for an extended period of time or simply stored too long, even in ideal conditions,” Brandon Parker, a research associate at the North Carolina State University Extension, explained over email. This tracks. Elana reports that she purchased this sweet potato from a farmers market in April and prepared it within days. While Elana didn’t store it for very long, given typical sweet potato growing seasons, Parker said the farmer likely harvested the sweet potato in the fall and then stored it for many months in too-warm and too-dry conditions that sucked its moisture away. 

“Sweetpotatoes naturally respire even after harvest and keeping them at a lower temp (55-60 deg. F) helps slow the respiration process down, thus preserving more energy (starch),” Brandon explained. “As they burn more energy over time they will get these air pockets like you see on the inside… You will also see these sunken valleys and wrinkled skin.”

So, basically, the sweet potato was shedding lots of water and looking to its own cells for fuel. Then, those cells deflated as dry air pulled moisture from them and as the sweet potato consumed its own starch to survive. (Because yes, that uncooked sweet potato in your pantry, like all your fresh produce is “alive,” respiring and running cellular functions until you cook it.) 

I also shared this image with Cole Gregorie, a sweet potato specialist at the Louisiana State University Ag Center. He said he had never seen anything quite like it before, but noted that it looked similar to some sweet potatoes he encountered several years ago. In that case, the fields flooded during the growing season and the potatoes dried out and looked similarly odd inside. He theorized that an influx of water plumped up the potato, making it extra easy for its cells to collapse when it later dried out. 

“I would not recommend eating this potato,” he said. “I don’t think this was unsafe, but I cannot imagine that the flavor quality of this potato was good at all.”

What are those circular patterns inside the sweet potato?

Gregorie explained the sweet potatoes grow in bundles around “poles” that run from one end of the potato to another. That’s why, if you snapped a sweet potato in two, it would break along jagged lines. In this case, he said, it’s possible that any stress it encountered in the field disrupted some of that growth. 

In any event, as moisture fled the sweet potato and cells deflated, some of that inner architecture became more apparent. The white areas are zones that—likely due to whatever trauma this sweet potato endured—are lacking the beta carotene that gives it an orange color, Gregorie said.

This sweet potato had lots of black areas after cooking

Elana, not one to be deterred by a food that looks a little unusual, proceeded with her meal prep and boiled the potatoes. This is where our story takes another interesting turn. The sweet potatoes turned black! Well, not uniformly black, but black-ish in various spots. 

When sweet potatoes blacken after cooking, that’s usually a reaction between certain protective compounds (chlorogenic acids) as well as naturally occurring iron in the sweet potatoes and oxygen in the air. Normally, when this happens, it might be more subtle and you might find it concentrated toward the ends of the sweet potato, where there’s relatively more chlorogenic acid. Here, and I need to be clear, this is just my theory, I’m wondering if stress caused the sweet potato to produce more chlorogenic acid, so there was more of it to enable the blackening reaction.

So, what did this potato taste like?

Elana and her partner tried the sweet potato, but ultimately opted against eating it. It didn’t taste quite right. And the black color was rather unappetizing. 

Could you safely eat potatoes with sunken areas like this?

As bizarre as it looks, there’s nothing obviously unsafe about this sweet potato. All its issues are physiological; there’s no sign of infection or of any circumstances that might have made it more likely to be sporting problematic levels of pathogens or chemicals that would sicken a person. On top of that, it was boiled, which doesn’t automatically make food perfectly safe, but definitely helps.