Why Do Potatoes Turn Green? Is It Safe To Eat Them?

Akinwalere Olaleye
Feb 29, 2024 By Akinwalere Olaleye
Originally Published on Dec 08, 2021
Why do potatoes turn green? Find out here.
Age: 3-18
Read time: 7.4 Min

Potatoes are one of the most versatile members of the vegetable family.

Potatoes are very easy to cook as well. But are green potatoes safe to eat, and why do they turn green?

French fries, mashed potatoes, salads, hash browns, tater tots, or wedges, baked, scalloped, au gratin, or roasted potatoes are the king when it comes to tasty food. Nothing can go wrong when it comes to potatoes, or maybe that is what you think because there are times when your potatoes can go green. Yikes! It does look slightly off-putting. You might observe a person simply peeling the potato skin away. Another might cut away the green part, while someone else might simply throw away the potato. But the true question is, why does a potato turn green? And are potatoes that turn green safe to consume?

You get to see a green potato due to the generation of chlorophyll in the potato. However, it may also lead to the development of a toxic substance called solanine, which can be harmful to the human body. Thus, it is always important to be careful when you purchase a potato sack, as it may contain a green potato or two. Continue reading about what makes a potato go green and how you can store them safely, so that stored potatoes do not turn green.

If you enjoy this article, find out the answers to other interesting questions, such as why cells divide and why your ears pop!

What makes a potato go green?

Having potatoes in your kitchen is literally a lifesaver. You can just pop out to the kitchen and make any dish you like at any time. It requires little effort to make the best of dishes, so why not store enough potatoes to last a lifetime, right?

But wait. You may slowly start to notice a green color on the skin of potatoes. Is it safe for a person to eat a green potato? How did this happen, you may wonder. Well, we have the answer to your question. The greening of all potatoes occurs naturally. When a bag of potatoes is left open and exposed to light, it naturally begins to produce chlorophyll. Chlorophyll is a green pigment present in leaves, plants, and algae, which gives them their green color.

As the production of chlorophyll begins, light-skinned potatoes begin changing their color from yellow to tan to light brown. They then start developing small green spots and then their skin starts turning green entirely.

This change of color is not only found in light-skinned potatoes! Even dark-skinned potatoes slowly transition to darker pigments, so identifying it might be slightly difficult. To actually realize whether the production of chlorophyll is taking place in a dark-skinned potato, you can scratch off a part of the skin and see if there is greening going on inside. If these potatoes produce chlorophyll, you can observe green patches once the skin has been peeled off.

Chlorophyll also assists in the process of photosynthesis and aids plants in harvesting energy when exposed to light. Thus, plants are able to produce oxygen and carbs from water, carbon dioxide, and sunlight.

It is the presence of this chlorophyll that causes potatoes to start turning green. This green color is usually harmless and is present in most of the foods we consume today. So it is not that potatoes turn green after cooking; it is this pigment.

Another reason why a potato turns green is when it grows quite close to the soil surface.

Are green potatoes poisonous?

If chlorophyll helps in developing food and oxygen, it must be a good thing, right? Then why are green potatoes not always recommended? Is green skin a warning sign?

Greening in potatoes may not always be a good sign. It may indicate the production of a potentially harmful plant compound. This toxic compound is called solanine.

Exposure to light does initiate the production of chlorophyll in potatoes. However, it also leads to the production of certain other compounds which can protect potatoes against possible damage from fungi, insects, bacteria, or even hungry animals. While being toxic to all of these creatures, they are also toxic to human beings at the same time.

When it comes to potatoes, toxic solanine is present in lower concentrations in the skin as well as the flesh of potatoes. However, it is present in much higher levels in different parts of the main potato plant. Exposure to light in potatoes causes the levels of solanine to increase. Even damaged potatoes are seen turning green.

The presence of chlorophyll in potatoes is, in fact, a good indicator of high concentrations of solanine in any potato. However, it may not always be an accurate measure, as the generation of both is independent of the other. Depending on the type of potato, one type may be seen turning green much sooner than another but may have a moderate concentration of solanine. Other types may turn green slowly but have much higher levels of solanine.

Thus, the greening of potatoes is one of the early symptoms of solanine being developed in a potato.

The presence of solanine in a green potato can make it dangerous to consume.

What happens if you consume too much solanine?

With solanine being a dangerous toxin, it is advisable to throw away any potato which seems to be turning green. However, there may be situations when you unknowingly consume such potatoes (maybe while eating street food). So, what truly happens if your body is exposed to solanine?

The solanine present in potatoes works by inhibiting a certain enzyme which contributes to breaking down neurotransmitters. It may also damage the cell membrane in the human body. Eating a green potato might also affect the permeability of your intestines.

It has not been deduced how much solanine will make someone sick. This differs from person to person, their health, and their tolerance. Many have fallen sick and suffered from solanine poisoning, but it is always recommended to keep safety in mind and throw away any potato which may be turning green.

Mild symptoms may heal quickly within a day or two. You may experience headaches, diarrhea, stomach pain, vomiting, and even nausea. In extreme cases, solanine poisoning may cause a coma, breathing problems, paralysis, convulsions, or sometimes even death.

With so many health issues, it is considerably better to discard the entire potato rather than peeling off the skin of the green portion. Do not cut away the green part and use the remaining section either, as you may still fall sick.

While eating a potato, if you experience a bitter taste, simply discard it, as a bitter taste is a sign of solanine being present in the potato. Cooking a green potato does not contribute to reducing the solanine levels either. Hence, it is considered best to discard the potato rather than cook it.

How can you prevent a potato from turning green?

Now that we know that green potatoes may be bad, the next question which comes is how to stop the green color from developing on the potato skin. We have the answer to your question!

Thankfully, cases of solanine poisoning are actually quite rare. Potatoes containing a high level of solanine often do not end up at grocery stores. However, if proper storage of potatoes has not been made, then you can expect green potatoes in large quantities stored in the warehouses of supermarkets or in people's kitchens.

Exposure to light, physical damage to potatoes, and even extremely high or extremely low temperatures are some of the main factors which contribute to the development of high levels of solanine, which is a toxin. Thus, proper inspection of potatoes is important before purchasing them; else, you can say hello to green potatoes.

Once you have brought your bag of potatoes, make sure to store them all in a cool, dark area. Preferable cool, dark spots include a basement and a root cellar. As sunlight causes the generation of solanine, it is advised to pack potatoes in either a plastic bag or in an opaque sack.

You may think that a refrigerator is an ideal place to store potatoes away from sunlight. But low temperatures of a refrigerator are not recommended for potatoes, as they can generate this toxin. Storing them away in a pantry or simply keeping them on the surface of the kitchen counter is also not advisable, as it may be too warm.

It is always advisable to buy smaller portions if you think you cannot store potatoes safely. Make sure to keep them away from light in a cool, dark place.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our article about why potatoes turn green,then why not take a look at our articles on why we need food or why leaves fall?

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Written by Akinwalere Olaleye

Bachelor of Arts specializing in English Literature

Akinwalere Olaleye picture

Akinwalere OlaleyeBachelor of Arts specializing in English Literature

As a highly motivated, detail-oriented, and energetic individual, Olaleye's expertise lies in administrative and management operations. With extensive knowledge as an Editor and Communications Analyst, Olaleye excels in editing, writing, and media relations. Her commitment to upholding professional ethics and driving organizational growth sets her apart. She has a bachelor's degree in English Literature from the University of Benin, Edo State. 

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