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Food Science: Why Potatoes Turn Green

2008_09_09-GreenPotatoes.jpgOur post the other week on the best place to store potatoes brought up an interesting food science (and food safety!) issue: why the skin on potatoes sometimes takes on a greenish color.

 
 

Potatoes naturally contain two types of alkaloids called solanine and chaconine - between 2 and 15 milligrams per quarter-pound according to food scientist Harold McGee.

Higher levels of these alkaloids can give potatoes a bitter taste and result in digestive problems. Very high levels can also cause neurological problems and can potentially be life threatening, though these cases are rare.

Stressful growing conditions and prolonged exposure to light can cause the alkaloid levels to steeply increase. Exposure to light also triggers chlorophyll formation in the skin and upper layers of the potato, causing the potato to turn - you guessed it - green.

Since they're both related to light exposure, greenish skin can indicate high alkaloid levels.

Again according to Harold McGee, you can still eat these potatoes if you peel away all the green skin and surface layers of the potatoes. If the greening is very deep or the potato tastes noticeably bitter, it should be discarded.

Related: Food Safety: Is It Safe to Order Hamburgers Rare?

(Image: Emma Christensen for the Kitchn)

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Food Science, Health, Ingredients - Vegetables, food safety, potato, green potato

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Comments (2)

after last weeks post, i seriously threw away all of my green, sprouting potatoes.. my mom always warned me, but since when did we ever listen to our parents advice??? haha

posted by deeboyayay on September 11th 2008 at 6:01am
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I am sure that many years ago I remember reading that potatoes that had this green (including potatoe chips), were dangerous for pregnant women to eat?

posted by gymfly on September 13th 2008 at 10:01am
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