Home Bread-Bakers v107.n036.1
[Advanced]

Re: The changing taste of sourdough

Mike Avery <mavery@mail.otherwhen.com>
Sat, 08 Dec 2007 10:33:14 -0700
v107.n036.1
Allen Cohn asked Bob,
>Are/were you feeding all these starters with the same flour? Perhaps 
>it's not the same air that's making them all start to taste the 
>same, but rather the same flour. The literature I've read says that 
>all flour has some microorganisms attached...so perhaps in time the 
>organisms in your flour come to outnumber whatever different strains 
>used to be in your world tour of starters.

I've thought about this topic a lot, and done more than a bit of 
research on the matter.  If you look at the romance of starting a 
starter, many people feel that you catch a starter from the 
air.  More recent information suggests that while it is not 
impossible to do this, it is very unlikely.  The concentration of 
yeast and bacteria on flour is much, MUCH higher than what is in the 
air.  Dr. Ed Wood wanted to catch a :"real" Egyptian starter, so he 
had some flour sterilized by having it irradiated.  When he put out 
containers of water and flour, he had a very high failure rate.  When 
some people in rec.food.sourdough wanted to replicate this, the 
poured boiling water on flour to have a poor man's 
sterilization.  And they found that they had over a 90% failure rate 
in starting starters, where normally they took success for granted.

So, the critters ARE on the flour, and will most likely be the source 
of a starter.

Similarly, the concentration of critters in an active and well 
maintained starter is many orders of magnitude higher than on 
flour.  It is unlikely that the critters in the flour will take over 
a culture. Cultures tend to be, if well maintained, very stable over 
long periods of time.

So where do changes in flavor come from?  There are two major areas 
where change can come in.  If you, like most people, have a natural 
starter you started with flour and water, it is a blend of different 
strains of yeast and bacteria.  (In Germany, it is common practice 
for a baker to order the exact strains s/he wants from a bakery 
supply house and have a very pure culture.)  In the natural culture, 
over a period of time one strain of yeast and one strain of bacteria 
will become dominant by orders of magnitude.  The rest are still 
there... biding their time. If you change the conditions under which 
you maintain your starter, the dominant strains can become minority 
strains, and the starter will change.  An all too common example of 
this is when strains that produce lots of proteolytic enzyme take 
over a culture.  Proteolytic enzymes break down protein.  A little of 
this is not a bad thing, it makes the dough extensible.  A lot of 
this is very bad, it turns the dough into soup.  These bacteria 
become dominant when the starter isn't fed enough and the critters 
that can eat protein instead of starches have an advantage.  (As an 
aside, starters that go down this path are best discarded.  You can 
partially rehabilitate them, but the next time you skip a few 
feedings, the balance will change and the proteolytic enzyme 
producing bacteria will be back in the drivers seat.

If we assume good starter management, where do changes in taste come 
from?  Hunters prize boars that have been feasting on acorns - it 
gives the meat such a nice taste.  (Or so I am told.  If anyone can 
send me care packages so I can try this treat myself, please send me 
an email. And French farmers feed their geese special herbs to give 
the birds livers a great taste that will be in the pate the livers 
will be used in.  If you have ever nursed a baby, or lived with 
someone who has, you have probably noticed the baby is sensitive to 
what mom eats.  What mom eats is expressed in her milk.  And the baby 
may decide not to feed until the baby is really hungry or that taste goes away.

If what a large organism eats can affect the taste of the organism, 
or its products, in a fairly short time frame, we shouldn't be too 
surprised that what a sourdough culture is fed will affect its taste. 
Flour is a commodity, but it is not as standardized as salt or sugar. 
There are differences from brand to brand, season to season and mill 
to mill.  So, even though the sack has the same name on it, the flour 
may not really be the same.  If you want to see a dramatic example of 
the differences flour can make, switch your flour to, or from, whole 
grain flours.  In just a few feedings, you'll see and smell amazing 
differences.  The differences between brands of white flour will be 
more subtle, but they will be there.  An independent confirmation of 
this is the baker's folk wisdom that says  if you want to duplicate 
another baker's bread, don't try to steal his sourdough culture, find 
out what kind of flour he is using.  Flour is the biggest part of 
bread, so this isn't a big surprise.

Mike

Mike Avery      mavery at mail dot otherwhen dot com