General: Potato Question

Subject: Potato Question
From: David Fulford-Brown (nospam-david.fulford-brown at
Date: Wed, 22 May 2002 20:08:37 +0100

Can anyone tell me please, when potatoes start growing the little tube things (sorry, don't know what they're called), are they still safe to eat? Likewise, we have green coloured potatoes. Are they still ok to eat?

Thanks for your help.

David F-B
From: Peter Aitken (paitken at
Date: Wed, 22 May 2002 19:17:28 GMT
The sprouted potatoes are safe but in my experience are usually past their prime and do not taste that great. You should not eat the sprouts themselves but trim them off as well as the section they are growing from. Green potatoes should be avoided. The green areas taste bitter and contain solanine, which is toxic.
From: nancree at (Nancree)
Date: 22 May 2002 19:58:03 GMT
Food Science Australia Fact Sheet

February 1994

Greening of potatoes

Why do potatoes turn green?

The role of a potato tuber for the potato plant is to produce the next generation of potatoes. It therefore contains nutrients in the form of starches, sugars, proteins and minerals for the new potato plant. When a potato tuber is exposed to light it turns green by producing chlorophyll and then can make extra energy for the new plant through photosynthesis. The green patches act in the same way as leaves do.

The potato plant also has the interesting ability to produce its own protective chemicals which can make it lethal to insects, animals and fungi which attack it. These protective chemicals (glycoalkaloids) are at high levels in the leaves, stems and sprouts of the potato plant and are normally at very low levels in potato tubers. However on exposure to light the potato tuber will produce elevated levels of these protective glycoalkaloids, with the highest levels being in the sprouts as they emerge from the tuber.

Potatoes will also produce high levels of glycoalkaloids (such as solanine) in response to bruising, cutting and other forms of physical damage, as well as to rotting caused by fungi or bacteria. In these instances high levels of glycoalkaloids are present in the potato. However in non-damaged potatoes, greening is a warning sign.

Are green potatoes safe to eat?

Green potatoes may cause food poisoning and since some of the symptoms are similar to gastroenteritis it is possible that some undiagnosed cases of gastroenteritis have been caused by eating green potatoes.

Human and livestock deaths have been recorded as a result of the consumption of greened or damaged potatoes with very high glycoalkaloid levels. It should be noted that glycoalkaloids are not destroyed by cooking processes, even by frying in hot oil. Consequently potatoes with pronounced greening or with signs of damage should not be eaten.

It is advisable that green or damaged potatoes are avoided by pregnant women or women who are likely to become pregnant, as there is some evidence of possible foetal damage or loss of the foetus from glycoalkaloid poisoning in animals.
From: Peg Haine (mlh4 at
Date: Wed, 22 May 2002 16:06:46 -0400

When potato eyes begin to sprout, the spuds are still OK to eat, as long as they're not mushy. But you don't want to eat either those sprouted eyes or any skin that's turned green. Remove both before cooking. I can't remember what the chemical is that's included in both those parts, but it'll give you one hell of a bellyache.