Learn More About a Topic
The green is nothing more than chlorophyll, a harmless compound found in all green plants. However, when potato tubers turn green there is usually an increase in a glycoalkoloid compound called solanine. Consequently, it is important to store potatoes in the absence of light to prevent greening. The green color of the potato is caused by exposure to light. According to PennState Extension, light causes the potato to produce chlorophyll and also solanine. Solanine has a bitter taste and is an irritant to the digestive system that can cause paralysis in large quantities.
When people worry about green potateos being poisonous, they should actually be worried about the toxic effects of all potatoes. Potatoes are, to a certain degree, poisonous, though not in a deadly manner, and usually not enough to make anyone sick. The leaves of potatoes do contain high levels of a certain poison, and are direct relatives of nightshade, a poisonous plant. Green potatoes, the lf spuds, may contain just a little more of this poison than do white ones, and reflect improper storage or growing methods.
The green color is not the issue. This is merely a sign that a potato has been exposed to light, prompting it to produce more chlorophyll, and chlorophyll is potwtoes toxic to how to be a project engineer. What creates the problem with green potatoes is that exposure to light also produces a substance called solaninea glycoalkaloid, which has been shown to be toxic when consumed in great quantities.
Scientists have sought to determine exactly what quantity of green potatoes it would take to cause human toxicity, and it turns out that an adult would have to eat about 4. There are some theories about whether regular consumption of potatoes that have gone green might reduce levels needed to produce poisoning. It is thought that it takes the body over a full day to clear solanine from the body, how long to hike kilimanjaro so eating potatoes that are green on a daily basis could have some cumulative affect or accumulate toxic levels more quickly.
This may leave cooks wondering whether they ought to eat green potatoes or discard them. For greatest safety, it is probably what if potatoes are green to discard potatoes that are green, to avoid consuming solanine.
Scientists have tried to assess exactly how much poison results from green potatoes, and here people may be in for a surprise. Some potatoes will retain their white color but have been exposed to light, and still have higher than normal solanine levels, and some greener potatoes have lower levels of this toxin.
One study in published in the Journal of Agriculture and Food Chemistry found that improperly stored potatoes accumulate most solanine in the peel. This might suggest that peeling the potatoes is the best way to get rid of this toxin, no matter the color of the potato underneath. She is especially poratoes about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.
Please enter the following code:. Login: Forgot password?
Dec 04, · That’s green-all-over potatoes. Alexander Pavlista at the University of Nebraska, Lincoln says that a lb person would have to eat about one pound of fully green potatoes to get sick. That is equivalent to one pretty large baked potato. His report recommends cutting away the green parts. Green skins contain mg/kg total glycolkaloids. Jan 22, · Green potato skin may be caused when a potato is stored on the kitchen counter or window sill, or even when the potato is grown too close to the soil surface, hence the recommendation to grow potatoes in a mound and store harvested potatoes in a completely cool, dark area. Green Potatoes. Q. Why do potatoes go green? Potatoes will often go green when they’re not stored properly and they're exposed to light. This is due to formation of chlorophyll (which is found in all green plants), however the green colour is a useful indicator that levels of certain toxins that are harmful to humans, known as glycoalkaloids, may be increased.
Want to learn how to plant sprouted potatoes to grow your own food? Just click the "Read More" button to the right. If you grow potatoes, you have probably seen some of them turn green. If so, you might be wondering what the green color on potatoes means, and how to prevent it.
So, why do potatoes turn green in sunlight? Potatoes turn green in sunlight due to the production of chlorophyll. Chlorophyll is a natural chemical produced by plants to aid in photosynthesis turning light into sugar.
Potatoes that turn green from chlorophyll may also contain solanine, which is a toxic substance. Of course, there are things other than sunlight that can cause potatoes to produce the toxic substance solanine.
Sunlight exposure is not necessary, but it does make potatoes produce solanine faster. Chlorophyll is a chemical produced by plants that makes them green. Chlorophyll also plays a key role in photosynthesis, or the process of turning sunlight, water, and carbon dioxide into sugar.
When a potato tuber the part of the plant that we eat! This is what causes the potato skin and possibly the flesh underneath to turn green. There are a few different factors that determine how much green appears on a potato, and how fast it happens. These factors include:. According to the University of Nebraska Lincoln, even low levels of light exposure for a short duration can cause greening:.
This means that potatoes still attached to the plant and exposed to strong sunlight can turn green in only one day. Even potatoes that have already been harvested and left out in the sun to dry can turn green in a single day.
However, light is not the only culprit in making potatoes turn green. Soil temperature also plays a role. Temperature makes a big difference in terms of whether a potato will turn green and how fast it happens.
At low temperatures, little or no greening of potatoes occurs. At warmer temperatures, potatoes can turn green fast. According to the University of Nebraska Lincoln:. This means that potatoes in cool soil are less likely to turn green for example, during the early fall.
On the other hand, potatoes that mature during summer and stay above the surface of the soil will soon turn green. Keep in mind that potato tubers can turn green whenever they are exposed to light — either outdoors or indoors.
This means that potatoes stored on a countertop where they are exposed to natural or artificial light will turn green. According to North Dakota State University:. The green comes from the pigment chlorophyll. Potato tubers exposed to light will become green naturally as the plant seeks to harvest the light.
In addition to light levels and temperature, the variety of potato also makes a difference in how fast potatoes turn green. In general, white-skinned varieties tend to turn green more easily than red- or russet-skinned varieties. Regardless of what type of potato you are growing, light is necessary for the production of chlorophyll to make the potato turn green.
According to Wikipedia, solanine is a glycoalkaloid produced by potatoes. Solanine is also produced by other plants in the nightshade family, such as tomatoes and eggplants. Most of the solanine in a potato tuber develops close to the skin. Potatoes produce solanine to help protect potatoes against natural enemies, such as:. The leaves, stems, and shoots of a potato plant all contain high levels of solanine.
However, the potato tubers the part we eat that grows underground can also produce high levels of solanine. According to Wikipedia:. This is a natural defense to help prevent the uncovered tuber from being eaten. This makes sense, since the tubers need to sprout in order to reproduce and make the next generation of potato plants. As mentioned earlier, potato tubers produce chlorophyll when exposed to sunlight. As it turns out, potatoes can produce solanine without light. However, light does speed up the process of solanine production.
While chlorophyll is tasteless and harmless if eaten, solanine is colorless but bitter, and it is toxic if eaten in large amounts. A potato can produce both chlorophyll and solanine at the same time. However, potatoes can also produce one without the other. So, a green potato may or may not contain solanine. Similarly, a potato that is not green may still contain solanine and be unsafe to eat!
Solanine is present in all parts of the potato plant, including the sprouts, roots, leaves, flowers and fruits.
Solanine can also harm human beings if eaten in large amounts. As mentioned earlier, potatoes can also create solanine without sunlight and without turning green. There are several things you can do throughout the growing season to prevent your potato tubers from turning green. One of the most important things is hilling, which is done during the growing season. Hilling your potato plants means that you put extra soil at the base of the plant, where the stem meets the soil line.
The purpose of hilling is to keep the tubers covered with soil and out of the sunlight. Potatoes produce tubers above the point where the seed potato was planted. Without proper hilling, some of the tubers produced later in the season will grow above the surface of the soil.
After exposure to sunlight, these tubers will turn green and start to produce solanine. To avoid this, simply use hilling a few times during the growing season.
All you need to do is pile a few inches of soil in a mound around the base of your potato plant as it grows. When the plant gets taller, just add a little more soil to the mound.
When you start to hill potato plants, begin when the plant is 6 inches 15 centimeters tall. Add 4 inches 10 centimeters of soil to cover all but the top 2 inches 5 centimeters of the plant.
Repeat this process throughout the season. By harvest, the hills around your potato plants could end up standing 12 inches 30 centimeters above the surface of the soil! When planting in containers or raised beds, I recommend a depth of 24 inches for potato plants.
This leaves enough room for both root growth and hilling during the season. A grow bag with a depth of 16 inches would be sufficient for growing potatoes. This method would also make it more convenient to harvest the tubers at the end of the season. You can learn more about the depth and space requirements for potato plants in my article here. In order to avoid frost damage to potato plants, it is important to plant them on time so that they can mature before frost arrives in the fall.
You can learn more about when to plant potatoes in my article here. It is also important to harvest potato tubers before the first fall frost. This avoids any cold damage that could cause tubers to produce solanine. Otherwise, use a pitchfork instead of a shovel. It is too easy to cut into the potatoes and cause damage with a shovel. You can also use a soil sifter to separate the potatoes from the soil watch out for those pesky rocks though!
Another idea to avoid injury during harvest is to grow potatoes in a bin with a door that lets you pull out the tubers easily without digging. Instead, put them in a low-light or completely dark place. Keep them at high humidity and cool temperatures of 45 to 50 degrees Fahrenheit 7 to 10 degrees Celsius for optimal storage.
Then, allow the tubers to sprout and plant them the following spring to produce more potato plants. If you are interested in learning more about this, check out my article on planting sprouted potatoes.
Another option is to cut off the parts of the potato that are green. If just a little bit of the skin is green, you might be able to salvage part of the potato for cooking. However, make sure to try a little bit of the potato before eating the whole thing. Remember that cooking does not remove chlorophyll and solanine. The potatoes will still be green after cooking them, and they will still contain toxic solanine that can make you sick!
Green potatoes can make you feel sick, but they can do more damage than that. According to the Iowa State University Extension:. They may also cause an upset stomach and more serious health problems. When in doubt, avoid eating potatoes that taste bitter or look green.
Now you know why potatoes turn green in sunlight. You also know what to do to avoid green potatoes and solanine. I hope you found this article helpful. If so, please share it with someone who can use the information.