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re: Sourdough evoloution

"Mike Avery" <mavery@mail.otherwhen.com>
Sat, 16 Mar 2002 17:40:19 -0700
v102.n013.8
On 10 Mar 2002 at 1:45, Brianjwoody@aol.com wrote:

 > The evolution is a result of local airborne yeasts slowly overcoming
 > the original. If you start with a San Francisco culture, and live
 > there too, it will stay as is for ever (except that local things
 > evolve too!). If you start in England with SF, as I did, it will
 > slowly change. How slowly depends on how you nurture the culture, but
 > change it will. You can freeze some of the original and reactivate at
 > intervals, after throwing away the one you have been using. That keeps
 > near the original for much longer. Cheers, Brian

There is so much mythology surrounding sourdough that it's often hard to 
tell what is going on.

A number of experiments have been done with trying to catch a culture using 
sterilized flour.  The success rate when using sterilized flour is much 
lower than when using plain off-the-shelf flour.  Using less processed 
whole wheat or rye flours instead of white flour further increases the 
chances of success.

This suggests the "culture from the air" theory is likely to be an old 
husbands tale.  In short, it doesn't seem very likely that yeast or 
lactobacillus from the air are that significant.... if starting a culture 
from local air is difficult, then there probably isn't enough in the air to 
take over a healthy, established culture.

My feeling is that the largest potential source of infection in the culture 
comes from the flour added to the starter.

And the greatest chance for the added flour to overwhelm the starter comes 
when the starter is not maintained in a healthy condition, or when the 
starter is given a very large refreshment.

Under test kitchen conditions starters have remained unchanged for 50 
years, and the test isn't over.

So, keep the culture healthy, and don't give it overwhelming feedings.

Mike