Wrong Nimrod. The purple color is carotenoid pigment like in all Solanaceae.
Potatoes also come in yellow, orange, pink and red even though you seldom
see those colors in general cultivation.

http://www.foodsubs.com/Potatoes.html

http://edis.ifas.ufl.edu/CV283


"martin" wrote in message
...
On Wed, 24 Mar 2004 00:50:43 -0600, "Bella" wrote:


"Jaques d'Alltrades" wrote in message
...
The message
from martin contains these words:

My wife has planted potatoes that are purple inside. She tried
cooking
some this evening, they lost their purple colour when cooked. Whoops!

Add a little white vinegar to the water when you're cooking them... a
small
amount (teaspoon?) shouldn't affect the taste noticably, but ought to be
enough to preserve the colour. (at least make it appear less grey)
I love using them... took me ages to convince my aunts that I did NOT add
blue food colouring to the mash potatoes last thanksgiving
I'll try growing them this year (BF's mother was our usual supply, but
they
live so far away...)

I guessed that the purple is caused by iodine reacting with starch.