Skip to Content

What does bad sweet potato look like?


Sweet potatoes are a delicious and nutritious root vegetable that can be a tasty addition to many meals. However, like any fresh produce, sweet potatoes can sometimes go bad. Knowing how to identify bad sweet potatoes can help you avoid wasting money on inedible ones at the grocery store, or accidentally using spoiled ones in your cooking. In this article, we’ll cover everything you need to know about how to tell if a sweet potato has gone bad.

What Causes Sweet Potatoes to Go Bad?

There are a few main reasons why sweet potatoes can spoil:

Storage Conditions

Sweet potatoes are living organisms that continue to respire after harvest. This means they still undergo metabolic processes that require oxygen. If stored in a low oxygen environment, sweet potatoes can begin to ferment which leads to spoilage. Ideal storage conditions for sweet potatoes include a well-ventilated area at around 55°F with high humidity.

Physical Damage

Sweet potatoes that get bruised, cut, or physically damaged are more prone to microbial growth like mold which causes them to decay faster. Avoid purchasing sweet potatoes with cracks, soft spots, or other physical defects.

Length of Storage Time

Fresh sweet potatoes will usually last 3-5 weeks when stored properly. The longer they are kept past their prime, the more likely they are to become shriveled, moldy, and inedible. Try to buy only what you plan to use within a few weeks.

Diseases

Various fungal and bacterial diseases can infect sweet potato crops while growing in the fields. Diseased sweet potatoes often start to decay and develop unappetizing textures or appearance soon after harvest. Only purchase sweet potatoes that look fresh.

Signs that a Sweet Potato Has Gone Bad

Here are some of the most common signs that a sweet potato is past its prime or spoiled:

Mold Growth

The appearance of mold on the surface of a sweet potato is a clear indication it has gone bad. Mold can vary in color but is most often fuzzy and white, grey, green, or blue. It may cover small patches or large areas. Moldy sweet potatoes have an increased risk of harboring mycotoxins and other harmful compounds and should always be discarded.

Shriveled or Sunken Skin

Fresh, high-quality sweet potatoes have smooth, taut, and unbroken skin. As sweet potatoes start to spoil, the skin will start to shrivel, wrinkle, or become sunken and softened. A lack of moisture causes the skin to pucker and shrivel.

Soft Spots

Press gently on the surface of the sweet potato. It should feel firm and rigid. Any indentations, squishy spots, or areas that give way under light pressure indicate spoiled flesh underneath. This is a sign of bacterial or fungal infection.

Discolored Flesh

Cutting into a sweet potato can reveal discoloration inside. While the flesh of a fresh sweet potato should be vibrant orange, spoiled ones may have greying, brown, black, purple or beige internal flesh. This happens when microbial growth and enzymes begin to break down tissues.

Strong Fermented Smell

A fresh sweet potato should smell earthy, starchy, and sweet. If you notice a sour, fermented odor coming from the potato, this is a red flag it has gone bad. An ammonia-like smell also indicates spoilage.

Liquid Oozing

Exudate is the release of liquid from inside produce as it deteriorates. If you notice any sticky fluid or oozing coming from a sweet potato, it means the interior structures have started decomposing into liquids.

Presence of Mold Spores

Even if you can’t see actual mold growth, inspect sweet potatoes closely for white/grey dust or particles on the skin surface. This is a sign mold spores are present which can quickly develop into mature mold given the right conditions.

Unusually Soft Texture Throughout

A freshly harvested, high-quality sweet potato should feel hard and dense when you squeeze it gently. An all-over soft or mushy texture indicates the starch has begun breaking down due to age or bacterial action.

How to Check a Sweet Potato for Freshness

Follow these simple steps when selecting sweet potatoes to find the freshest ones:

Inspect Skin

Avoid sweet potatoes with cuts, cracks, bruises, or other defects. The skin should be taut and smooth without wrinkles, shriveling, or sunken areas.

Check Weight and Shape

Choose firm, heavy sweet potatoes that feel dense when lifted. Avoid ones with rounded or misshapen ends which often signal improper growth.

Look for Mold

Check all sides for visible mold growth. Also look for grey, brown, or black soft spots which are signs of subsurface mold.

Feel for Firmness

Gently squeeze each potato. Pass on those with a spongy or mushy texture. Opt for ones that feel hard and rigid all over.

Smell Aroma

Give sweet potatoes a sniff. The aroma should be pleasantly earthy and sweet, not sour, fermented, or unpleasant.

Examine Cut Surfaces

For a more thorough inspection, ask a grocery produce worker to cut a small slice so you can check the interior flesh for odd colors or softness.

What Do Spoiled Sweet Potatoes Taste Like?

It’s important not to taste sweet potatoes that show any signs of spoilage. Consuming spoiled or moldy produce can cause food poisoning.

However, some descriptions of the taste of a spoiled sweet potato include:

– Fermented, sour, bitter flavor
– Unpleasant starchy or cloying taste
– Ammonia-like or rotten taste
– Moldy earthy taste
– No sweetness detectable

The natural sugars in sweet potatoes break down as they spoil, so they lose their characteristic sweetness.

Can Spoiled Sweet Potatoes Make You Sick?

Yes, it is unsafe to eat sweet potatoes that are past their prime or visibly spoiled. Consuming decaying produce introduces potentially hazardous bacteria, mold, and toxins into your body which can cause illness.

Potential health risks include:

Food Poisoning

Common foodborne pathogens like E. coli, salmonella, and listeria can grow on spoiled produce and lead to nausea, vomiting, diarrhea, cramps, fever, and chills after ingestion.

Allergic Reactions

Mold spores present in decaying food can trigger allergic symptoms in sensitive individuals. Reactions may include skin rash, sinus congestion, breathing issues, and other problems.

Toxicity

Mycotoxins and other chemical compounds produced by molds on spoiled food have toxic effects in the body such as organ damage, neurological issues, and immunosuppression.

Serious Infections

People with compromised immunity are more vulnerable to potentially life-threatening illnesses caused by eating microbiologically contaminated produce.

Long-Term Health Effects

There are concerns that regularly consuming moldy produce may have chronic adverse health effects over time such as cancer risk and liver disease. But more research is needed.

Safe Food Handling of Sweet Potatoes

When dealing with fresh sweet potatoes, adhere to good food safety practices to keep them in prime quality for as long as possible:

– Wash hands before and after handling
– Scrub sweet potatoes thoroughly before cooking
– Avoid cross-contaminating cooking spaces and utensils
– Refrigerate whole unwashed sweet potatoes between uses
– Cook sweet potatoes within a few weeks of purchasing
– Never leave cut potatoes out for over 2 hours
– Discard any potatoes that smell bad or appear spoiled
– When in doubt, throw it out!

What to Do With Bad Sweet Potatoes

If you discover spoiled sweet potatoes, do not try salvaging them. Any washed, peeled, or cut sweet potatoes that show signs of spoilage should be immediately discarded in the trash or compost bin.

Whole raw sweet potatoes that are going bad can be safely turned into livestock feed provided they are still firm and have no mold. Always err on the side of caution and throw them out if you have any concerns over their safety or quality. Prevent waste by purchasing only what you plan to cook within a week or two.

How to Store Sweet Potatoes Properly

To extend shelf life, be mindful of how you store fresh sweet potatoes:

Cure Them First

Before storage, cure fresh sweet potatoes for about 5-7 days in a warm, humid location around 85°F. This helps heal scrapes, thicken skins, and extend storage life.

Choose a Cool Spot

Ideal storage temperature is 55-60°F with high humidity around 85%. A basement or pantry cupboard works well. Avoid refrigeration.

Provide Ventilation

Ensure storage area has good airflow. The respiration process causes moisture loss so ventilation is key. Use breathable containers like burlap sacks or wire baskets.

Protect From Light

Exposure to light causes sweet potatoes to start sprouting and deteriorate faster. Store them in a dark cupboard or opaque bag.

Avoid Moisture

Wet conditions breed bacteria. Keep sweet potatoes dry by lining containers with paper towels to absorb excess moisture.

Check Frequently

Inspect stored sweet potatoes every week and remove any that are spoiled. One bad potato accelerates spoilage of others.

How Long Do Sweet Potatoes Last?

With proper post-harvest curing, storage methods, and minimal handling, fresh sweet potatoes can potentially last:

– Whole, unwashed sweet potatoes: 3-5 weeks
– Whole, cured sweet potatoes: 1-3 months
– Cooked sweet potatoes: 5-7 days in refrigerator
– Canned sweet potatoes: 12-18 months when unopened
– Frozen sweet potatoes: 8-10 months

The shelf life depends largely on the initial quality and minimizing damage. Buy only fresh, uncracked tubers and store them carefully in a consistently cool, dark, and ventilated place.

Summary

Aging, physical defects, poor storage conditions, and diseases are all factors that can cause fresh sweet potatoes to deteriorate in quality. Signs of spoilage include mold, wrinkled skin, soft spots, discoloration, bad aromas, exudate, and an abnormal texture. Spoiled sweet potatoes are unsafe to eat and should be discarded. Choose firm, uncracked sweet potatoes with intact skin, proper curing and storage in a cool dark space can maximize their shelf life and freshness. With vigilance, you can avoid bad sweet potatoes and enjoy their optimal flavor, texture and nutrition when used in your cooking.