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Gill Matthews · 04-08-2007, 08:26 AM posted to uk.rec.gardening

In article , says...
"keith" wrote:

The green appears to be only on the
peel but I have read somewhere that green potatoes can be poisonous.

It's caused by exposure to light, before or after harvest. I forget the
chemical name; the green pigment is toxic, but is destroyed by heat. So
unless you eat your spuds raw (I went to a talk by a potato and tomato
breeder, and he does just that to test), I wouldn't worry.

Gary Woods AKA K2AHC- PGP key on request, or at home.earthlink.net/~garygarlic
Zone 5/6 in upstate New York, 1420' elevation. NY WO G

Because of the interest provoked by the other green potato thread I looked out
the original new scientist article which was actually one of the last word articles.
I then back checked in my lecture notes (my degree was in plant biochemisty)

The green colour is chlorophyll and is not toxic, However it is a symptom that a
toxic chemical called solanin is being produced in the potato. Solanin is not
soluble in water and is not likely to be destroyed by ordinary cooking temperatures.

properly stored potatoes ie not green contain between 100-200mg per kg of solanin. In
green potatoes this can increase to 1000mg per kg about 70% of the solanin is stored
in the outer 5mm of the potato it is distributed throughout the skin not just in the
green bits.

Toxic doses of solanin are 3-6mg per kg of body weight so a person weighing 50kg (about 8 stone)
would be able to eat up to 750g (1.6lb) of properly stored unpeeled potato without risk of ill
effect. The safe dose would go down to 150g (5oz) of unpeeled green potato. If only one end
of the potato was green and you cut it off, but cooked the rest of the potato with its skin
on or only scraped it you may run into trouble, but if you peeled the potato all over then
you could safely eat quite a lot (depends on depth of peeling)

Solanin tastes bitter (apparently) and I would therefore not eat any potato that tated bitter
I would hesitate to serve green potatoes to children because they have a low body mass and
a large appetite.

Solanin is a neurotoxin at low doses is causes dry mouth and palpitations at higher doses
it causes halucination and paralysis followed by death. solanin toxicity and death in humans
has been reported but here my stats are hopelessly out of date as it is a long time since I
left Uni

Gill M