Have you ever peeled a sweet potato and left it on the cutting board for a few minutes just to come back and find that it had turned brown?
Skin discoloration is a phenomenon found in most fruits and vegetables when cut and left in the open for some time. Sweet potatoes are no exception.
If you dislike how fast your sweet potatoes can turn brown when peeled, then this article is for you. Read on to learn how to keep your sweet potatoes fresh.
Why Do Sweet Potatoes Turn Brown?
Most fruits and vegetables go brown for two reasons. If they’re discolored the moment you cut them up, then that’s mold, and the vegetable or fruit you got has gone bad.
If you cut them up, and they slowly obtain a brown or gray tint, then it’s due to oxidation. This is when the chemical composition of an object changes as it reacts with the surrounding oxygen.
When it comes to sweet potatoes, an enzyme called polyphenol oxidase is the main culprit. This enzyme’s purpose is to protect plants against parasites. It’s sealed within the vegetable’s skin.
When any breakages happen to the rind of the fruit or vegetable, this enzyme is activated. It then subsequently reacts with oxygen and results in these brown-and-gray spots we dislike.
Because sweet potatoes are chock-full of it, they turn brown in such a short time.
These changes cause the exposed skin of the sweet potatoes to not only lose their firm bright appearance but also to lose their appetizing taste.
5 Tips to Prevent Sweet Potatoes From Turning Brown
If you want to know how to preserve your sweet potatoes, buckle up as we discuss all the probable strategies you can try.
1 – Place Them in a Bowl of Water
The best way to slow the process of oxidation is to place the peeled or cut pieces of sweet potatoes in a bowl of cold water. Store them in the refrigerator if you have to.
Water molecules will act as a layer of insulation that will prevent the skin from interacting with the oxygen in the air. Adding a pinch of salt can act as a preservative as well.
With this assortment, you can store your peeled sweet potatoes up to a day before cooking them. For optimum results, use a glass or plastic bowl.
2 – Use an Acid
Adding a small amount of white vinegar and/or fresh lemon juice can be extremely helpful, too. Acids help prohibit the enzyme polyphenol oxidase from activating.
You can apply these acidic elements by rubbing the sweet potatoes with them once peeled or cut. You can also splash them into the bowl of water they’re soaked in.
If you’re worried about flavor changes, here’s a useful tip: add one teaspoon to every half gallon of water. This ratio will sort everything out.
It’s worth mentioning that acids don’t only prevent browning, but they also make it brighter, and thus more appealing.
3 – Parboil Them
Parboiling is when you boil a vegetable or fruit for a short amount of time, without fully cooking it.
It’s well-known that a key component to having enzymes work is to place them at their optimum temperature.
However, boiling removes this element from consideration, and therefore, the enzyme simply becomes inactive.
Just like soaking sweet potatoes, parboiled ones can be stored for a day before turning bad. They can also be frozen, for longer preservation.
4 – Use a Glass Cooking Dish
It’s also been proven that aluminum and metal containers can react with sweet potatoes, and cause them to brown quickly.
5 – Wait Right Before Cooking
The easiest step you can take is to simply wait. Don’t peel or cut the sweet potatoes until you have everything else prepared and ready to immediately cook them.
How to Tell If Your Sweet Potatoes Are Bad
Whether you’ve stored them or just got them anew, sweet potatoes are the type of vegetable that can easily go bad.
Learning how to notice the signs of a bad sweet potato can save you a lot of time and effort. Here’s how to detect the signs of a rotten sweet potato:
1 – Discoloration
It’s no surprise that sweet potatoes turn brown/gray when left out a lot. However, this doesn’t mean it’s immediately inedible.
Rotten sweet potatoes often have a darker blackish tint, though. This usually isn’t enough of a sign, but it’s the first one we notice.
2 – Check the Texture
Just like regular potatoes, sweet potatoes have a seamless firm skin. If that’s not the case, then you might want to hold back from eating it.
Having a spongy and soft texture is often one of the first signs that this sweet potato has started to go bad.
3 – Non-Uniform Surface
Look out for the presence of any odd extrusions on the surface of the sweet potato. These growths can be rot or mold, and thus should be immediately discarded.
Eating mold can be detrimental to your digestive system.
Be mindful of sprouts, though. They might look like weird protrusions but their presence is as natural as can be.
It’s safe to say that sweet potatoes might not keep as well as regular potatoes, and there’s a reason for that. Sweet potatoes are jam-packed with oxidizing enzymes that are highly reactive.
However, there are many ways you can prevent them from oxidizing and turning brown. When done right, you can easily store them well, with or without refrigeration.
One thing you can do is soak them in chilled water. You can add salt or acids for optimal preservation. You can also rub acids like vinegar or lemon juice on them before storage for further protection.
Acids further ameliorate the skin’s appearance by making it brighter, and by prohibiting the oxidizing enzymes present. Parboiling can deactivate them as well.
However, all this can go to waste if the cooking container can react with the sliced pieces of sweet potatoes. Therefore, it’s recommended to use a glass cooking dish for good measure.
This process is enough to ward off any browning, as well as rot or mold, and will keep your sweet potatoes from going bad for as long as possible.
Sarah is the founder of Baking Kneads, LLC, a blog sharing guides, tips, and recipes for those learning how to bake. Growing up as the daughter of a baker, she spent much of her childhood learning the basics in a local bakery.