So the other night, we are eating at a restaurant after my son’s basketball game. (His team didn’t win, but thanks for wondering.) In the midst of enjoying our meal, my 12-year old daughter picks up a waffle fry and asks “Mom, why is my fry green?” Being the good mom that I am, I respond “That is a GREAT blog topic!”. Needless to say, that wasn’t exactly the answer she was looking for. She rolled her eyes and said “Fine as long as you give me credit for the idea, but really, why is my fry green?”
Green areas on potatoes are caused by exposure to light. As a root crop, grown properly, potatoes do not see the light of day until harvest. Under the cover of soil, they have no green color whatsoever.
The green color in any vegetable is called chlorophyll. It is a really important part of helping the plant take in the sunlight and convert it into energy so that the plant grows at a healthy rate and produces a healthy vegetable for us to eat.
However, if potatoes are grown with exposure to sunlight, the area exposed begins to develop chlorophyll in the skin tissue. Of course we know that potatoes are not supposed to be green, but it’s not the chlorophyll that is the problem. A potato’s exposure to light also causes these areas to become bitter which is a result of too much “Glycoalkaloids” accumulating in the same area as the chlorophyll. (Hang in there with me, I’m not going to get too science-y).
Glycoalkaloids are natural compounds that contribute to the flavor of vegetables, but in high concentrations, can be bitter. If too much of these compounds are eaten, they can have some not so pleasant side-effects, such as nausea and diarrhea. (uugghh) So it’s a legitimate fact not to eat green potatoes. Small amounts are not a problem, but the general advice is to cut out the green portion of potato and discard or compost it.
Potatoes can also become green tinged after harvest while at the grocery store, exposed to continuous lighting which contributes to the changes in color. It can also happen at your home. Anytime the potatoes are exposed to too much light. The “greening” of potatoes happens more quickly at temperatures above 65 degrees Fahrenheit, and generally does not happen at less than 40 degrees. A good reason to store your potatoes in a cool, dark place. That’s why a lot of old farm houses still have “root cellars”, an old fashioned form of cold storage.
Other Random Potato Facts:
So what other funky facts can I tell you about potatoes?
If you’ve ever cut into a potato that is hollow, it has what is called “Hollow Heart”. This results from some sort of environmental stress, usually an extreme heat fluctuation during the early growing season when the potato is most fragile.
Brown center is another condition consumers may find when cutting up a potato. This can also be caused by heat stress but also by dry soil conditions or not enough nutrients available for the plant to keep the potato from being stressed. Neither one of these conditions is a result of disease, but due to stress the plant may have undergone during a critical stage of the growing season.
If you’re a backyard gardener and want to grow potatoes, you should have a plot large enough to rotate to a different location each year. Divide your space into quarters and don’t go back to the same section for 4 years. This is due to the soil diseases that potatoes are susceptible. Don’t plant tomatoes, legumes, or strawberries after potatoes as these crops are susceptible to the same soilborne diseases. Planting them in the same location year after year builds up those diseases. We used to grow potatoes, and now we grow Roma tomatoes and strictly follow a 4-year crop rotation so that the crop stays healthy and the soil replenishes itself. Crop rotation is always advisable for both farmers and gardeners and is considered a best management practice. Your garden plot should also be well-drained. Potatoes do not like standing in water
Potatoes prefer a soil pH of 5.2 to 5.5. Check your pH soil fertility before planting and incorporate any amendments into the plot before planting. Backyard growers typically over-fertilize potatoes resulting in large vine growth but poor potato production. If you use manure, make sure it is composted manure.
Potatoes can be part of a nutritious diet for consumers. Potatoes are high in potassium and a good source of Vitamin C and fiber. Potatoes themselves are not fattening. They have no fat or cholesterol. How WE prepare them and of course our portion size can make them fattening.
The popular notion that the majority of nutrients in a potato are found in the skins is false. Nutrients are found throughout the entire potatoe.
I know this is way more than you wanted to know about potatoes… but some curious mind, like your 12-year old daughter, might ask and so now you know!