Eating sprouted potatoes that have gotten soft is generally not recommended. However, whether or not it’s actually unsafe depends on a few factors.
What causes potatoes to sprout and get soft?
Potatoes sprout and get soft when they have been stored for too long. Over time, the starch in potatoes starts converting to sugar. This causes the sprouts to grow and makes the potato flesh soften.
The conversion of starch to sugar is a natural process that occurs due to the potatoes trying to grow new plants. The sprouts are the new shoots and stems trying to emerge. Meanwhile, the softening occurs as the starch structures break down.
Are soft sprouted potatoes safe to eat?
Soft sprouted potatoes may not be outright unsafe to eat, but they tend to have poorer flavor and texture compared to fresh potatoes. The high sugar content gives them an unpleasant sweet taste, and the soft flesh feels unappealingly mushy when cooked.
Overly softened sprouted potatoes also have reduced nutritional value. Levels of vitamin C and various B vitamins deteriorate during prolonged storage. So very old sprouted potatoes provide less nutritional benefit.
Of greatest concern is the potential buildup of toxins in soft sprouted potatoes. Two types of toxins can accumulate to unsafe levels:
- Solanine – A bitter, poisonous glycoalkaloid produced naturally by potatoes as a defense against insects and disease. Solanine levels are normally very low in potatoes, but they increase as potatoes age and sprout.
- Acrylamide – A potential carcinogen that forms in starchy foods when they are cooked at high temperatures. Longer storage leads to higher sugar levels, which can increase acrylamide formation during cooking.
Research shows solanine and acrylamide levels are significantly higher in soft, sprouted potatoes compared to fresh ones. Frying or baking older sprouted potatoes is particularly problematic, as the high heat greatly accelerates acrylamide production.
Reducing potential toxins in soft sprouted potatoes
If you want to consume soft sprouted potatoes, there are ways to reduce potential toxins:
- Cut away green spots and sprouts – These contain the highest concentrations of solanine.
- Peel the potatoes – Much of the solanine accumulates close to the skin.
- Soak in water – Soaking helps leach out some solanine.
- Boil or microwave – Cooking with lower heat prevents acrylamide formation.
- Limit portion size – Eating small amounts reduces toxin exposure.
However, these preparation methods cannot completely eliminate the risks. Peeling and cutting away sprouts does not remove all solanine or acrylamide precursors. And boiling does not get rid of toxins that have already formed within the potatoes.
How can you tell if sprouted potatoes are unsafe to eat?
It can be difficult to determine if the toxin levels in a sprouted potato are high enough to cause illness. There are some signs that may indicate a potato is too far gone and potentially dangerous to eat:
- Very long sprouts (over 1/2 inch) emerging from multiple areas on the potato
- Extremely shriveled, wrinkled appearance
- Severely softened flesh throughout the entire potato
- Greenish, grayish or blackish colors inside the potato
- Strong bitter taste, especially around sprouts and green spots
- An overall foul, rotten odor
Potatoes displaying these traits are at very high risk of having toxin levels capable of causing food poisoning. It’s best to discard sprouted potatoes with these characteristics.
Can you eat mashed or fried soft sprouted potatoes?
Mashing or frying soft sprouted potatoes is not recommended. These cooking methods do not get rid of toxins already present:
- Mashing – Mashing or pureeing potatoes distributes solanine and acrylamide precursors throughout the entire dish. This ensures any toxins are consumed.
- Deep frying – Frying accelerates acrylamide formation in sprouted potatoes due to the high heat. Deep frying at temperatures above 300°F has been shown to increase acrylamide levels by 10-fold or more.
Boiling is the safest cooking method, as it leaches out some toxins and prevents further acrylamide formation. However, boiling cannot remove all the risks of eating old sprouted potatoes. It’s generally better to avoid cooking soft, sprouted potatoes altogether.
What are signs of solanine or acrylamide poisoning?
Solanine and acrylamide poisoning can cause similar symptoms. However, solanine poisoning tends to occur soon after eating contaminated potatoes. Acrylamide exposure builds up over time with regular consumption.
Possible signs and symptoms include:
- Nausea, vomiting, and diarrhea
- Abdominal pain and cramping
- Headache and fever
- Confusion, dizziness, and hallucinations (in severe cases)
- Weakness, paralysis, and impaired motor function
- Liver and kidney damage
- Increased risk of cancer over the long term
Seek medical attention if experiencing severe or persistent symptoms after eating sprouted potatoes. Immediately call emergency services if rapid onset of vomiting, diarrhea, confusion, hallucinations, paralysis, or other serious symptoms develop.
Can you eat sprouted potatoes if you cook them thoroughly?
Thorough cooking does not necessarily make soft, sprouted potatoes safe to eat. Cooking helps reduce potential foodborne illness from bacteria or fungi. However, it does not get rid of toxins like solanine and acrylamide:
- Solanine withstands cooking and is not easily broken down by heat or other food preparation methods.
- Acrylamide forms during high temperature cooking like baking, roasting, broiling, and frying. Boiling does not create acrylamide.
In fact, cooking at very high heat can make sprouted potatoes more toxic by rapidly increasing acrylamide formation. While thorough cooking eliminates risks from bacteria, it does not remove the hazards from solanine or acrylamide in old, sprouted potatoes.
Can you eat potato sprouts?
Potato sprouts should not be eaten. The sprouts contain very high levels of toxic glycoalkaloids like solanine. Just 3-6 mg of solanine per kilogram body weight is enough to cause poisoning.
One laboratory analysis found solanine concentrations between 5.6 to 13.4 mg per 100 g of potato sprout material. Eating even a few sprouts could easily deliver dangerous amounts of solanine.
Eating soft, sprouted potatoes is generally unsafe due to the potential for solanine and acrylamide toxins. While taking proper precautions like soaking, peeling, and boiling can reduce some risks, they cannot completely remove the danger.
Discarding severely sprouted potatoes showing signs of very high toxin levels is advised. If you choose to eat softened sprouted potatoes, stick to small portions of boiled potatoes for the least risks. But avoiding sprouted potatoes altogether is the safest option.