Here are some quick ways to tell if a sweet potato has gone bad:
- It smells foul or rotten
- It is shriveled, wrinkled, or mushy
- It has black or brown spots
- It has mold on the skin or flesh
- It tastes bitter, sour, or unpleasant
One of the first signs that a sweet potato has gone bad is its appearance. A fresh, good sweet potato should be firm and smooth, with no wrinkles, shriveling, or mushy spots. The skin should be intact with no cracks or bruises. The flesh inside should be bright, vibrant orange or yellow with no darkening or greying.
As a sweet potato starts to spoil, you may notice these changes:
- Wrinkling or shriveling of the skin as moisture evaporates
- Soft or mushy spots as starches start to break down
- Grayish, brown, or black discoloration inside the flesh
- Mold or bluish-black spots on the skin or flesh
- Cracks, bruises, or wet spots on the skin
- A watery or milky substance oozing from cracks
These are all signs that the sweet potato’s tissues are breaking down and it is rotting. The sweet potato is past its prime and should be discarded at this point.
In addition to checking the appearance, you can judge the freshness of a sweet potato by its texture and feel. A firm, unspoiled sweet potato will feel heavy and dense. The skin should be taut and difficult to pierce. Pressing the flesh lightly should leave no indentations or fingerprint marks.
As the sweet potato starts to go bad, you’ll notice these textural changes:
- Lightness or a loss of weight as moisture is lost
- Soft indentations when pressed due to the breakdown of starch
- Spongy or mushy feel throughout
- Wrinkled or shriveled skin that has lost tautness
- Skin that is easily pierced when pressed
Sweet potatoes that exhibit these signs of textural changes should be discarded and not eaten.
Sniffing a sweet potato is one of the easiest ways to detect spoilage. A fresh, unspoiled sweet potato has an earthy and starchy smell that is not unpleasant. There should be little to no odor.
If your sweet potato smells anything like these, it has gone bad and should be thrown out:
- Sour, fermented scent
- Alcoholic odor
- Fruity or vinegar-like smell
- Ammonia scent
- Rotten or moldy smell
These odors indicate microbial growth and the breakdown of starches into alcohols, organic acids, and gases. Even if the sweet potato looks alright, strong unpleasant odors mean it should not be eaten.
The final check for freshness is tasting a small piece of the flesh. A good sweet potato should taste sweet, starchy, and a bit earthy. There should be no bitter, sour, or unpleasant flavors.
Here are some tastes that indicate spoilage:
- Sharp bitter taste
- Acidic or vinegary tang
- Alcoholic flavor
- Fermented, yeasty taste
- Moldy or musty taste
- Slimy texture
These off-flavors show that the sweet potato’s starches and sugars have broken down into other chemical compounds. Discard any sweet potatoes with an odd taste straight away.
In addition to checking for signs of spoilage, you can avoid bad sweet potatoes by storing them properly. Here are some storage tips:
- Store whole, unwashed sweet potatoes in a cool, dark, well-ventilated place around 55-60°F.
- Do not refrigerate raw sweet potatoes. The cold converts their starch to sugar, giving an unpleasant taste.
- Place them in a basket or bowl, not sealed in plastic, so air can circulate.
- Consume within 1-2 weeks for best quality and freshness.
- Cooked sweet potatoes can be refrigerated for 4-5 days.
With proper storage conditions, sweet potatoes will stay fresh longer and avoid premature spoilage.
Signs of Spoilage in Specific Sweet Potato Varieties
There are many different varieties of sweet potatoes, and each may show signs of spoilage a little differently. Here are some specifics:
Orange-Fleshed Sweet Potatoes
- Look for black/brown spots, soft wet spots, mold, and wrinkling.
- Smell for a fermented, alcohol-like odor.
- Taste for a tangy, bitter, or fermented flavor.
White-Fleshed Sweet Potatoes
- Look for graying, wet spots, mold, and very wrinkled skin.
- Smell for a rotten, sulfurous odor.
- Taste for a sharp bitter, medicinal flavor.
Japanese Sweet Potatoes
- Look for very wrinkled, deflated skin and dark discoloration.
- Smell for a sour, vinegar-like scent.
- Taste for a very acidic, tangy flavor.
So in summary, be on the lookout for discoloration, wrinkling, mold, wetness, and other signs of breakdown in the skin and flesh. Rely on your nose to detect rotten odors. And use taste to discern any sour, tangy, bitter or fermented flavors.
What to Do With Spoiled Sweet Potatoes
If you determine your sweet potato has gone bad, the safest thing to do is throw it out. Do not try to eat spoiled sweet potatoes, as they can make you ill. Here are some other tips for handling spoiled sweet potatoes:
- Discard the spoiled sweet potato in the trash or compost. Do not try to preserve it.
- Remove any other aging sweet potatoes from storage to prevent cross-contamination.
- Wash your hands after handling rotten sweet potatoes.
- Clean any containers, bins or baskets that stored the bad sweet potato.
- Consider masking unpleasant odors by placing coffee grounds or baking soda in the compost.
With vigilance checking for signs of spoilage, prompt removal of any bad sweet potatoes, and proper storage conditions, you can keep your sweet potatoes fresh and delicious.
Frequently Asked Questions
How can you tell if a sweet potato has gone bad?
Look for wrinkled skin, mushy or discolored flesh, mold, and bruising. Smell for foul odors and taste a piece to check for bitterness, sourness, or off flavors. If in doubt, throw it out.
Do sweet potatoes go bad?
Yes, sweet potatoes will eventually spoil and go bad once harvested. Properly stored whole sweet potatoes can last 1-2 weeks at cool room temperatures around 55°F. Cooked sweet potatoes last 3-5 days refrigerated.
Can you eat a sweet potato that has mold?
No, you should not eat sweet potatoes with mold. Mold is a sign of spoilage and can cause health issues if ingested. Discard any sweet potatoes with mold on the skin or flesh.
What happens if you eat a bad sweet potato?
Eating a spoiled, rotten sweet potato can cause foodborne illness leading to nausea, vomiting, stomach cramps and diarrhea. Moldy sweet potatoes may cause allergic reactions. It’s best to avoid bad sweet potatoes.
Can sweet potatoes make you sick?
Fresh, unspoiled sweet potatoes are not harmful. However, spoiled, moldy, or rotten sweet potatoes can make you sick. Consuming them can lead to food poisoning or allergic reactions in some cases.
- Discard sweet potatoes with wrinkled skin, bruises, mushy spots, mold, or discoloration.
- Sniff sweet potatoes and throw away any with a foul, fermented, or rotten smell.
- Taste a small piece and toss sweet potatoes with a bitter, sour, or odd flavor.
- Never eat moldy or rotten sweet potatoes, as illness may result.
- Promptly remove spoiled produce and sanitize storage areas to prevent further spoilage.
Checking sweet potatoes for signs of spoilage by appearance, texture, odor, and taste will help you determine if they are bad. Discard any that are wrinkled, moldy, foul-smelling or unpleasant tasting. With proper storage at cool room temperatures and using within 1-2 weeks, you can enjoy delicious fresh sweet potatoes and avoid food safety issues from consuming bad ones.