Maybe not a proper gardening question but a lot of the potatoes we buy in
the supermarkets just now ,turn green.The green appears to be only on the
peel but I have read somewhere that green potatoes can be poisonous.Has
anyone in the group noticed this and also should we be worried ??

"keith" wrote in message
...
Maybe not a proper gardening question but a lot of the potatoes we buy in
the supermarkets just now ,turn green.The green appears to be only on the
peel but I have read somewhere that green potatoes can be poisonous.Has
anyone in the group noticed this and also should we be worried ??
Yes I've noticed it on my aunt's potatoes but she ate them with no ill
effects

"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

"Gary Woods" wrote in message
news
"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

Thanks Gary and Robert. I feel better now !I remember when I used to grow
spuds if any pushed through the soil when growing they turned green and I
just dumped them in case.
Robert,Nothing to do with spuds or gardening but it is nice to see someone
from Plymouth. I spent a lot of time there in 1940s and 50s in Drake
barracks and on different ships .

"keith g" wrote in message
...

"Gary Woods" wrote in message
news
"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

Thanks Gary and Robert. I feel better now !I remember when I used to grow
spuds if any pushed through the soil when growing they turned green and I
just dumped them in case.
Robert,Nothing to do with spuds or gardening but it is nice to see someone
from Plymouth. I spent a lot of time there in 1940s and 50s in Drake
barracks and on different ships .
Oh I see, Drake's still there as you know I expect although the city is
changing fast these days. You must have been serving during the war?

Hi Keith,



Don't be worried but take care! I started this thread because several of my
main crop potatoes had been exposed to sunlight and showed large areas of
green but I didn't want to throw them away. I have since become both
confused and, at the same time, blasé about the topic because I've read (not
really meaning to!) many articles on potatoes both before and since my
original question to the group and the answers seem to depend on where you
look and what you read.



According to this group, cutting away the green part and eating the rest,
cooked, is okay - and that's what I think, agree with, and intend to do. I
believe they to be right.



However, I would like to add some statements that I have since found and
read on various websites on the Internet. I know you really can't trust all
you read on the Internet but the following points sound reasonable to me and
do come from sources that have a certain amount of authority.



Firstly, the on-line New York Times says that potatoes (a relative of deadly
nightshade) naturally produce small amounts of solanine as a defence against
insects, but the levels increase with prolonged exposure to light and warm
temperatures. The green, caused by chlorophyll in the potato, therefore, is
an indication that the level of solanine has also increased above the normal
amount. This "greening" can occur both when the spuds are growing and lie,
uncovered, above the ground and when they are stored - so make sure you keep
them in the dark. I use the strong, lined paper sacks in which greengrocers
get their potatoes delivered and then put the bags in the garage.



The above article also goes on to say that, according to a report by a
gentleman by the name of Alexander Pavlista, apparently a professor of
agronomy and horticulture at the University of Nebraska, Lincoln, a 100 lb
(just over 7 st.) person would have to eat a full 1 lb of fully green potato
to get sick.



Yet another article (from Wikipedia) says that solanine can be partly
destroyed by cooking at temperatures over 170 °C (or 340 °F), which is way
above boiling temperature.



What I didn't know before was that all potatoes contain a small amount of
solanine, anyway, so the best thing to do, it seems, is to cut away the
green parts and fry the rest as chips!



I must admit, the older I get the more I realise how dangerous this eating
and drinking business is! I'd give it up but it's become a habit, now!



Regards,



John

"keith" wrote in message
...
Maybe not a proper gardening question but a lot of the potatoes we buy in
the supermarkets just now ,turn green.The green appears to be only on the
peel but I have read somewhere that green potatoes can be poisonous.Has
anyone in the group noticed this and also should we be worried ??

Whoops! Sorry Keith but this is not actually the same thread I started! I
made the mistake because the title you used is the same as the one I used!

I apologise but hope what I said helps you. It's the same problem, in a way.

John

"keith" wrote in message
...
Maybe not a proper gardening question but a lot of the potatoes we buy in
the supermarkets just now ,turn green.The green appears to be only on the
peel but I have read somewhere that green potatoes can be poisonous.Has
anyone in the group noticed this and also should we be worried ??

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

Thanks Gill,

That's answered the question brilliantly!

I'm surprised (but shouldn't be) at the different answers to the question
that you can find in books and the Internet so this clears it up nicely.

I am sure you are right so thanks again.

Just a couple of points that I would like clarified, please.

You say about 70% of the solanin is stored in the outer 5mm of the potato.
Is this true of both the green and ordinary potato? I would assume so. If
so, wouldn't it be better, and safer, to peel all potatoes? My wife insists
on not peeling potatoes because of the fibre in the "skin" - would you
consider this to be a safe thing to do or not?

You say, "is not likely to be destroyed by ordinary cooking temperatures"
but doesn't the high temperature of baking remove some of the solanin - and
the hot fat when cooking chips?

Thanks again!

Regards

John

"Gill Matthews" Try the wrote in message
T...
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

In article ,
"John Vanini" writes:
|
| You say about 70% of the solanin is stored in the outer 5mm of the potato.
| Is this true of both the green and ordinary potato? I would assume so. If
| so, wouldn't it be better, and safer, to peel all potatoes? My wife insists
| on not peeling potatoes because of the fibre in the "skin" - would you
| consider this to be a safe thing to do or not?

No. Something like 80% of the ascorbic acid is, too, and that counteracts
the solanin.

| You say, "is not likely to be destroyed by ordinary cooking temperatures"
| but doesn't the high temperature of baking remove some of the solanin - and
| the hot fat when cooking chips?

The former, yes. I don't know if solanin is soluble in fat.

| 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.

They typically also have a high sensitivity to bitterness.


Regards,
Nick Maclaren.

On Fri, 3 Aug 2007 18:22:03 +0100, "keith" wrote:

Maybe not a proper gardening question but a lot of the potatoes we buy in
the supermarkets just now, turn green.

Supermarket lighting + clear plastic bags can cause potatoes to go
green in 12 hours. :-( Look at them in the shop and don't buy them
if they are starting to go green. Once you get them home take them out
of the plastic bag (moisture encourages greening, it's part of the
process of growth after all) and keep them in a paper bag (ideally an
old potato sack) in a cool dark place.

NB, Not refrigerated, fridge temperatures cause potatoes to spoil.

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

Potatoes, Solanum Tuberosum, come from the same family as deadly
nightshade. 8-((

The greening which is simply chlorophyll accompanies the development
of alkaloid poisons (one of which is Solanine) which are at high
levels in the green parts of the plant (stems and leaves) and the
fruit but normally at very low levels in the tubers, they have been
bred to be like that, so don't eat wild potatoes if you find any.

Mild cases of poisoning cause the same symptoms as other digestive
upsets, griping in the gut, squitters etc. and probably go
unidentified and unreported. Rarely, serious cases have caused deaths
in humans, none AIUI since WW2. Historically the story goes that
serious poisoning has occurred when starving people have had nothing
else available to eat but green potatoes.

The only safe recommendation has to be don't eat green potatoes, or
potatoes which have sprouted. It is not sufficient to cut away the
greened part, and cooking does not destroy all of the poisons. The
eating of green potatoes by pregnant women is suspected to be a
possible cause of foetal damage or stillbirth.

Has anyone in the group noticed this and also should we be worried ??


No need to worry, you'd need to eat several pounds of them to cause
serious symptoms. Women of child-bearing potential should perhaps be
more circumspect.

DG

"Robert (Plymouth)" remove my other
hobby to reply wrote in message ...

"keith" wrote in message
...
Maybe not a proper gardening question but a lot of the potatoes we buy in
the supermarkets just now ,turn green.The green appears to be only on the
peel but I have read somewhere that green potatoes can be poisonous.Has
anyone in the group noticed this and also should we be worried ??
Yes I've noticed it on my aunt's potatoes but she ate them with no ill
effects

I usually just cut off the green bits, and I think I'm still alive!

In message , Gary Woods
writes
"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.


My understanding was that it wasn't the green pigment (which I assumed
was chlorophyll) but an alkaloid (solanine) which is coproduced. (All
parts of potatoes, other than the tubers, are poisonous.)

http://www.actahort.org/books/38/38_20.htm

I also doubt that cooking is sufficient to destroy solanine; one
anecdote that I've heard is of a variety which didn't make it to market
because a chap at the research station fried up a batch of tubers, and
consequently went down with solanine poisoning.

http://en.wikipedia.org/wiki/Solanine
--
Stewart Robert Hinsley

In article ,
Stewart Robert Hinsley writes:
|
| My understanding was that it wasn't the green pigment (which I assumed
| was chlorophyll) but an alkaloid (solanine) which is coproduced. (All
| parts of potatoes, other than the tubers, are poisonous.)
|
| http://www.actahort.org/books/38/38_20.htm

Yup. Except that even the tubers are, though only very slightly.
Solanine seems to be one of the many natural toxins where a long
term, low dose does no significant harm - cyanide is another.
Quinine is not.

| I also doubt that cooking is sufficient to destroy solanine; one
| anecdote that I've heard is of a variety which didn't make it to market
| because a chap at the research station fried up a batch of tubers, and
| consequently went down with solanine poisoning.
|
| http://en.wikipedia.org/wiki/Solanine

That's what I found in the research papers, too.


Regards,
Nick Maclaren.