Dietmar Tietz Dietmar.Tietz at agrar.uni-giessen.de
Fri Nov 18 03:35:40 EST 1994

On 16 Nov 1994 sdigby at TIGGER.STCLOUD.MSUS.EDU wrote:

> In article <3aa2f3$gkg at mserv1.dl.ac.uk>, Dietmar Tietz <Dietmar.Tietz at agrar.uni-giessen.de> writes:
> >
> >
> >Dear Bionetters:
> > 
> >I have the following question:  
> > 
> >In the USA, boiled potatoes usually change from yellowish to grayish or 
> >brownish colors.  In Germany, most of the potatoes retain their nice 
> >yellow color even until the next day.  What is the reason for this?  Does 
> >this depend on the potato variety, cultivation (i.e., fertilization, kind 
> >of soil), and/or climate?
> > 
> >Thanks in advance,
> > 
> >Dietmar Tietz
> >
> Dietmar,
> on checking a plant physiology book - the change in color seems to have
> something to do with the oxidation of chlorogenic acid and chlorogenic acid
> may be involved in protection against pathogens.  On the other hand, is
> anything added to the water in which the potatoes are boiled in Germany (e.g.
> vinegar?)  This might be why they do not change color.
> Stephanie 

thanks for the information explaining the physiology of the color change in
boiled potatatoes.  In Germany, we do not add anything to the boiling 
water other than a little salt.  But that did not make a difference when 
I cooked my potatoes in the USA.

According to a response I received from Beverly Erlebacher, Toronto 
Canada, the loss of yellow color has something to do with the variety. 
She wrote: "For some reason, yellow-fleshed varieties of potatoes have 
not been popular in North America, although they are common in Europe.  Recently
a yellow-fleshed cultivar called Yukon Gold was developed at the University
of Guelph in Ontario and is becoming widely available.  It is usually sold
at a somewhat higher prices than 'ordinary' potatoes.  I've both grown and
eaten this variety, and they are tasty and productive potatoes with a nice
yellow colour even after cooking.  Some farmers in Prince Edward Island 
have recently developed and released another yellow-fleshed variety 
called Island Sunrise, so yellow potatoes may be taking off on this side 
of the Atlantic."

An interesting question is, whether these yellow-fleshed potatoes contain 
less chlorogenic acid and are less resistant.  Could that be a reason for 
North-Americans to prefer other varieties?

Thanks again,

Dietmar Tietz
Giessen, Germany

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