Why does sweet potato turn black?

In this guide, we will address and answer the query, “Why does sweet potato turn black?” and answer other similar related questions like “Can you eat a sweet potato that has turned black?

” and “How do you tell if a sweet potato is bad?”

Why does sweet potato turn black?

Sweet potatoes turn black due to exposure to oxygen. When sweet potatoes are peeled, the flesh is exposed to oxygen in the air which causes it to turn black. 

Sweet potatoes also turn black due to the presence of polyphenol oxidase (PPO) enzymes in the sweet potato flesh that is exposed to oxygen when it is peeled. These enzymes react with oxygen to produce melanin, a dark pigment that gives the sweet potato its black color.

This darkening of the sweet potato flesh is not harmful and does not affect the taste or nutrition of the vegetable. Sweet potatoes are still safe to eat after they have turned black.

What factors accelerate the blackening of sweet potatoes?



Bruising can make sweet potatoes black because the impact can break open the cells and release the pigment that gives the potato its color. This can happen if the potato is dropped or if it is hit by something hard.

Bruising can also cause sweet potatoes to discolor because the cells release their contents when they are damaged. This can include the pigment that gives the potato its color. When this pigment is released, it can cause the sweet potato to turn black.


One of the main reasons why sweet potatoes can turn black is spoilage. When sweet potatoes are stored for too long, the natural sugars in the potatoes can start to turn into alcohol. 

This process is accelerated by warm temperatures and high humidity. Once the alcohols start to form, they can cause the potatoes to turn black.

Fungal infection

A fungal infection on sweet potatoes will cause the potato to turn black. The fungus will cause the potato to rot and the black color is a result of the decay.

 Fungal infections can occur when the potatoes are stored in damp conditions or if they are not cleaned properly before cooking. If you suspect that your sweet potatoes are infected with a fungus, throw them away and do not eat them. 

To prevent a fungal infection, make sure to store sweet potatoes in a dry, cool place. Do not wash them until you are ready to cook them. If you must wash them, use warm water and dry them thoroughly before storing them.

How do you tell if sweet potato is bad?

The skin of sweet potato should be firm, and the flesh should be free of blemishes. If the sweet potato has wrinkled skin or soft spots, it is probably bad. 

If you cut into a sweet potato and find that it is mushy or has dark spots and if it has a bad odor, it is probably bad. Moldy sweet potatoes should not be eaten. It is best to discard a sweet potato if it has the defects above.

Can you cut a mold off a sweet potato?

Yes, it is okay to cut the mold off of a potato. Just make sure to cut at least an inch below the moldy part and to wash the potato thoroughly before cooking it.

Can you eat a sweet potato that has turned black?

Starchy vegetables like sweet potatoes tend to oxidize when exposed to oxygen. They turn from a gray color to brown color and then finally turn black.

It is safe to eat a sweet potato that has turned black due to oxidation. Sweet potatoes that turn black due to other reasons such as fungal infection should be discarded.

Is sweet potato healthy?

Sweet potatoes are rich in fiber, vitamins, and minerals. They are a good source of vitamins A and C, potassium, and manganese. They are also a good source of fiber, which can help to regulate blood sugar levels and promote a healthy digestive system.

Sweet potatoes have been shown to have a positive effect on blood sugar levels. In one study, people who ate sweet potatoes had lower blood sugar levels after eating than those who did not eat sweet potatoes.

Can you peel and slice sweet potatoes ahead of time?

Yes, you can peel and chop your sweet potatoes ahead of time and store them in a bowl full of cold water. After preparing them, toss them in the refrigerator.

For more details on how to freeze sweet potatoes. Click here

Other FAQs about Sweet Potatoes that you may be interested in.

How to reheat sweet potato fries

Can you eat sweet potatoes without cooking?

How many sweet potatoes should be prepared for a single person? 

What is the real difference between a sweet potato pie and pumpkin pie


In this brief guide, we have addressed the query, “Why do sweet potatoes turn black?”  We have also discussed “Can you peel and slice sweet potatoes ahead of time?” “Can you peel mold off a sweet potato?”

Hope you found this blog useful, if you have any questions, please let us know.