Why Do Sweet Potatoes Turn Brown?

January 28, 2023

Sweet potato is one of the best versatile root vegetables that I love the most. It’s not only me; as humans, the love we have for root vegetables runs back thousands of years, and the best part of them for me is the unmatchable earthy flavor. Usually, sweet potatoes are resilient and got what it takes to remain edible for an appreciable period of time. However, sweet potato browning is one common issue that comes as part and parcel of the game. Why do sweet potatoes turn brown? I have the answer that you are searching for; let’s get started.

So, Why Do Sweet Potatoes Turn Brown?

As you most probably would know, keeping peeled sweet potatoes overnight is kind of a challenging job. But they tend to go brown even before you peel off; why? Here are some of the reasons that I figured out.  

Failing to Use Them Timely

The main reason for brown spots on sweet potato that I can point out is keeping them unused for a long time. Although you bring them down to your kitchen, you might not have gotten a chance to cook them.

So, take a minute and think about how many days you have left them without cooking before you put the blame on other factors. As I mentioned, I do like sweet potatoes, and when I buy them, I ensure to cook within ten days to eliminate the risks of spoilage.

Improper Storing

Sweet potatoes, in fact, all root veggies for that matter, must be kept away from moisture when you store them. If not, anticipating a prolonged lifespan is nothing but a joke.

So, why do sweet potatoes turn brown? Perhaps it’s you who did the wrongdoing by providing faulty storage conditions. It doesn’t demand much from you; just store the sweet potatoes in a place where they get no moisture; they call it cool and dry!

Also, do not store them with or near onions as it will lead both parties to get spoiled within a short period of time. For those who bought the canned version, it will last at least up to a year or so. Maybe that is irrelevant to the topic but essential, I guess.

Damages during Transport

Due to the sturdy nature of sweet potato, it might be difficult for you to spot the damages at the point of you buy it. Damages are bound to happen during the supply chain, and over time these damages can promote the growth of mold.

Finally, you would end up with brown holes in sweet potato. So, I want you to spend some time with the yams without just putting them in your cart.

Those are the three main factors that contribute to brown patches or holes on unpeeled sweet potatoes. However, understanding such factors is not rocket science, and you don’t have to read this article to figure them out on your own.

All you have to do is have an eager look at the veggie. In almost all such occurrences, you can simply cut off the problematic area to use the rest of the root without much of a problem.

But, you can never predict the brown spots inside sweet potato until you cut it. Even the smoothest appearing sweet potatoes might be spoiled inside. In fact, these are the spots that you have to worry about rather than the ones on the skin. 

Why Do Sweet Potatoes Turn Brown after Peeling?

Do sweet potatoes discolor after peeling? Indeed they do. This discoloration is called sweet potato oxidation, and it is more of a chemical reaction. Let me explain this a wee bit.

Sweet potato is a veggie that is full of phenolic agents, and a molecule called chlorogenic causes dark spots to appear inside of it when combined with oxygen and iron ions. I highly recommend you to cook your yam right after you peel to minimize this issue. 

You have a few hours at your disposal if you are cooking on the same day, but in order to use the cut pieces day after, you must put them in a water-filled bowl and store them in the fridge. 

How to Prevent Sweet Potatoes from Turning Brown before Cooking?

So, you have cut the sweet potato, and something happened and want more time to cook the cut pieces. By following the simple methods below, you can keep them from browning until you cook. 

First, take a bowl with water and add the pieces into it. This will help the sweet potato pieces to stay away from air. Then, add a pinch of salt into the water; keep in mind to rinse off the pieces before you cook. 

Alternatively, you can add lemon or lime juice to the sweet potato. Not that it will prevent the pieces from getting brownish, but also bring out bright color from the flesh of the yam. If possible, always try not to prepare the sweet potatoes ahead of time; that is the easiest way to keep them from turning dark. 

why do sweet potatoes turn brown

How to Prevent Sweet Potatoes from Turning Brown after Cooking?

Have you ever come across sweet potato darker inside after cooking? Chlorogenic is the culprit again. The chemical reaction that I mentioned previously can create the same issue because of the water as well.

If you put water into the recipe (unavoidable, right?), there is a high possibility of dark spots after the cooking. That is the main reason for sweet potato discoloration after cooking. 

How to Keep Sweet Potatoes from Turning Brown after Cooking?

Suppose you took every possible action up until now to keep the shape and color of sweet potato, and you want it to remain the same even after you cook. Most probably, you want your dish to preserve for future use. In that sense, you must know how to store them safely. 

In order to keep sweet potatoes from turning brown after cooking, put them in a shallow container or a food storing zipper bag before you store it in the fridge. 

If you follow this process, there shouldn’t be an issue in keeping them edible for at least up to five days. Keep the Chlorogenic reaction in mind, and never allow air into the cooked yam when you store it in the fridge.

Do you know how to reheat sweet potatoes using different methods?

If Sweet Potatoes Turn Brown, Can I Still Eat Them?

The most likable side of the story is that you can easily remove the brownish part of the yam and consume the rest without much of an issue, especially when the problematic part is on the skin.

That said, I do not recommend consuming sweet potatoes that have shrivels. Such indications tell that the moisture of the yam is vanished out and is unpleasant to eat. 

Another exception is mold. Although you can cut off the dark spots in order to use the rest, you cannot do the same with the ones that have mold growth. When it comes to inner flesh, it is alright to cook when there are tiny little holes here and there. If there are black holes all over the place, I’m afraid such yams only deserve the trash bin. 

Wrapping up..

Sweet potatoes are yummy and nutritious when they are in their optimum condition. You can still consume even when there are brownish spots on them as long as you follow my instructions. That’s the core message of this article. With that, I say goodbye, and if you have anything to ask with regards to why do sweet potatoes turn brown, the comment section is all yours. 

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