Black Spots On Sweet Potatoes – What Does It Mean?

Delicious and nutritious, sweet potatoes are in kitchens everywhere, and rightly so. From pies to fries, sweet potatoes are a colorful all-purpose vegetable.

Whether you’re baking, boiling, or BBQing your sweet potatoes, black spots can be concerning and unappetizing.

What do black spots on sweet potatoes mean? If your sweet potatoes have small black dots, they are still safe to eat. These can mean anything from bruising and oxidization to chemical reactions from cooking. However, if your sweet potato has deep black pits, that is a sign of rot and you should discard it.

If you want the most out of your spotty sweet potatoes without wasting the entire bunch, this article will explain why your sweet potatoes get black spots, what to do about it when it happens, and how to prevent them as much as possible.

Black Spots on Sweet Potato Skin

Like almost any vegetable, sweet potatoes are not immune to bruising. Small black spots on the surface of sweet potatoes that aren’t indented can be caused when they are being harvested and packaged.

Generally speaking, they are not handled like delicate eggs, but rather plucked from the ground and tossed into bins to be packaged and shipped.

With all the roughhousing sweet potatoes go through to get to your kitchen, it’s not unusual for them to have some battle wounds.

Black spots can simply be a little bruised skin, or they can be caused by a wound that allowed bacteria to get in and grow a bit of mold.

Luckily, little spots of mold on the sweet potato skin aren’t too much of a problem. Most of the vegetable is still totally fine. Just cut out the black spots as you’re peeling the potato and cook as planned.

However, be wary of sweet potatoes with deep black pits that bleed into the flesh below the skin. This is black rot and is unsafe to consume.

Black Spots on Peeled Sweet Potatoes

Even if you thoroughly check your sweet potatoes for black spots prior to peeling, it’s not uncommon for them to turn black or grey after being peeled. In fact, it’s almost guaranteed to happen.

Why do sweet potatoes turn black after peeling? Oxidization. Just like other kinds of potatoes and some fruits like apples and bananas, when the flesh is exposed to the air, it oxidizes and changes color.

This might look gross, but it makes no difference to the edibility or flavor of the sweet potato. 

To avoid the color change in the sweet potato when you are peeling, put them directly into a bowl or pot of cold water. You can further prevent blackening after peeling by adding a little salt, vinegar, or lemon juice.

The acids halt the oxidation process, allowing them to keep their delightful color while you are prepping the rest of your meal.

Black Spots on Cooked Sweet Potatoes

Sometimes you can get all the prepping right and the sweet potatoes still change color and turn black in the cooking process.  

Sweet potatoes are actually kind of delicate. They don’t always show their bruises right away, so the color develops slowly as they cook and the structure of the potato changes.

Sweet potatoes can get deep bruises just from being stored. Having them sitting in a pile for too long can result in internal bruising that doesn’t show when the potato is raw.

Another reason for blackening during the cooking process is a chemical reaction that sometimes happens when other ingredients are added before the potatoes have fully cooked.

You can avoid this by simply adding all your other ingredients to the sweet potatoes after you can easily push a fork into the potato.

Miscolored sweet potatoes may not be as pretty as you had imagined, but their flavor shouldn’t change noticeably. 

Black Spots Inside Sweet Potatoes

Spots in the middle of a sweet potato could have a couple of different causes. Sweet potatoes are fussy about how they like to be stored. 

The Goldilocks of the potato world, if sweet potatoes get too hot or too cold, they will spoil. They prefer their temperature to be consistently just right.

Ideally, your sweet potatoes should be stored in a cool (not cold), dark place and in a single layer, whenever possible, to avoid bruising. 

Try to visually inspect each sweet potato before storing them. If you notice any visible damage or punctures, separate that potato and use it as soon as possible, always keeping an eye on the damage and removing any mold that may develop. 

If you find just a couple of black spots inside your potatoes, you can just cut the spots out and carry on cooking.

If the concentration of black spots is close to overwhelming the natural orange color of the potato, it might be best to cut your losses and chuck that one into the trash.

Brown Spots Inside Sweet Potatoes

If you find yourself with a sweet potato that has brown spots inside of it, it could be just a bruise and you could leave it or cut it away.

To know if the spot is a bruise and not something even less appealing, have a look, feel, and smell of the sweet potato in question.

If the discoloration is just one or two little spots, the quality of the potato is likely not compromised in any way. You can leave the spots or cut them out, depending on your personal sensitivities and how you’re preparing the potatoes.

If your sweet potato smells foul, it’s spoiling and should be tossed immediately. Any vegetable that smells like rot should never be eaten.

You can also give your sweet potato a little squeeze. Sweet potatoes should be consistently firm. If you notice that the sweet potato is soft, squishy, or spongy, it’s time to toss it.

A sweet potato that is not good and firm is on its way to spoiling and the texture issues you’re detecting with your hand will also be apparent when you eat the cooked version.

How To Tell If Sweet Potatoes Are Bad

Sweet potatoes are not shy about letting you know when they’ve gone bad. Normally, sweet potatoes are firm. Soft spots on a sweet potato are the first sign that the vegetable is going bad.

Thoroughly soft potatoes are ready for composting, especially if they’ve transitioned from spongey to mushy and start to leak liquids.

However, this is not the same as a firm sweet potato leaking white liquid. We have a separate article if you’re curious about what this is.

Bad sweet potatoes will also be very smelly. Even if you could stomach the sight and smell, you should not eat sweet potatoes that have gone this bad.

Sometimes the opposite happens, and sweet potatoes get dehydrated. If you have a sweet potato that is getting shriveled and wrinkly, it has also passed its prime and will likely taste bad.

Occasionally, if the conditions are right, sweet potatoes will start to grow right in your cupboard.

If they have only a few eyes you can easily cut or pull them off. If you have a full-on plant about to bloom, it’s probably better to put it in the ground rather than eating it.

Related Questions

My Sweet Potato Is Growing Roots – Can I Still Eat It?

Sometimes we let sweet potatoes sit in the pantry for longer than intended. If we get lucky and they don’t spoil, they could start growing. 

If your sweet potato is starting to throw out little white roots, what do you do? These new roots can easily be plucked, peeled, or cut off. If you get to your potato early enough, there will be no effect on how it tastes.

If the sweet potato has grown lots of roots and even leaves, it will have changed in flavor and texture. A mature sweet potato that has transformed into a plant will have a woodier texture and lose the majority of its sweetness and flavor.

Why Do Sweet Potatoes Discolor After Peeling?

Similar to an apple, if you peel a sweet potato and leave it uncovered, it will start to turn a greyish, black, or brown color.

This happens because, when the flesh of the sweet potato is exposed to the air, a chemical reaction occurs and it starts to oxidize. 

Oxidation happens to a lot of fruits and vegetables but luckily, aside from looking less than perfect, it’s normal and safe and won’t alter the taste or texture of your food. 

Up Next: Recipe – Spanish Sweet Potatoes