Solanine poisoning – how does it happen?

Have you ever wondered why parts of your raw potatoes were green? Did you ask yourself if they were safe to eat?

February 7, 2014 - Author: Jane Hart, Michigan State University Extension

I recently had a call from a woman wanting to know if the potatoes she had were safe to eat. They had turned green under the skin, and she had heard one shouldn’t eat them if they are discolored this way. She wondered if what was “bad” on the surface of the green potato would go all the way through it, like food coloring did when she soaked the bottom of a peeled potato in colored water in elementary school science class.

A study done by Purdue University stated that the green coloring in a potato is caused by chlorophyll. Chlorophyll is caused when the vegetable is stored in light. Potatoes grow underground and should be kept in the dark. When they are stored on a counter or a place that gets regular light, chlorophyll is produced.

Potatoes that grow at the top of a hill can especially be affected by chlorophyll which is why in the store some are green. The chlorophyll then turns the white of the tuber green under the skin. The more light, the greener they become.

The green part of a potato should be discarded. It is bitter, and more than that, it contains solanine, which eaten in great quantities can cause illness. Solanine is an alkaloid which is colorless. Symptoms of solanine poisoning include:

Because it’s bitter, most people have learned to scrape the green part off before eating the potato. Michigan State University Extension urges you to wash all produce before preparing and eating in order to avoid illness from bacteria and pesticides. Also be sure to peel the green and “eyes” off a potato before cooking to avoid solanine poisoning.

Our ancestors knew best on how to store produce. They would keep their root cellars full throughout the year. We can learn from them and keep our unprocessed foods, like potatoes, in a cool, dark place. The plastic and netted bags most potatoes come in from the store allow light in, so find a burlap or brown paper bag in which to store them.

If you don’t have a dark storage place, buy only enough that will be used in a short amount of time. But if that isn’t done, at least you will have the natural warning of the green potato to keep you from eating the alkaloid solanine! Nature has a way of warning us through looks (greening) and bitter taste.

Tags: food preservation, msu extension, safe food & water

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