Science of Cooking: Ask the Inquisitive Cooks!

" Does a green potato=poison? "

I'm always a little concerned when I see green on potatoes. My wife tends to be more casual about it. Tonight we have local potatoes grown here in Palmer, Alaska; 'golds', I think. They are definitely green but have no sprouts. Joy says, 'Don't use sprouted potatoes that are green as the green portions as well as sprouts are poisonous.' Since there are no sprouts, are the green portions not so bad or does green=poison?

—Concerned in Palmer, Alaska

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The greenish hue is actually chlorophyll, but it is also an indicator that an alkaloid, called solanine, may be present under the skin of the potato. Solanine develops in potatoes when they are stored in the presence of light (which also encourages chlorophyll formation) and either at very cold or quite warm temperatures. It is toxic, however it would take a very large number of green potatoes to make you ill.

Since solanine collects just under the skin, it is safe to peel away the skin and a thin layer of white flesh before you cook the potato. And you're right about the sprouts: They too can be toxic and shouldn't be eaten, though it would take many sprouts to make you ill.

It's best to check potatoes for any green coloring before you buy them. Then, store them at cool room temperature in a dark, dry place.


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