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2. Stability Of Sourdough Starters


This article is from the Sourdough Starters FAQ, by Brian Dixon briandixon at hotmail.com.

2. Stability Of Sourdough Starters

The stability of the sourdough starter symbiotic relationship
determines the stability of the starter in whatever location the
starter is being maintained. In other words, when you move a starter
to a new area, it will become bombarded by new strains of wild yeast
and lacto-bacillus that are native to the new area. If the new
microorganisms are able to live within the symbiotic environment that
the Russian sourdough starter provides, then the starter will change
characteristics (flavor, usually) as the local microorganisms
multiply in the starter. Any and all microorganisms found in your
starter are open to changes in relative concentration if the local
microorganisms are 1) different and 2) can survive in your starter.
It is even possible that the original species present in your starter
(yeast and the lactobacilli) may slowly die off, being replaced by
the species in the local area. There is no guarantee that your
starter will stay the same as the original, but there is also no
guarantee it will change.

For this reason, it is suggested that if you wish to maintain a
special starter in its original form, that you immediately dry and
save much of the original starter as soon as you can after receiving
it (see NOTE below). For example, the Russian starter mentioned
above could have been fed once, to make it fresh and active, then
dried and frozen in multiple Ziploc bags. When it is noticed that
the flavor is drifting (or any other characteristics are changing),
then you can toss the changed starter and restart some fresh from one
of the frozen bags. Every so often you should replenish the freezer
supply with freshly restored starter. This technique can result in
your special starter maintaining its original characteristics for a
much longer time. But, since you do need to feed the starter at
least once before drying and freezing the stuff, and the drying
starter is exposed to the local air, even this technique will not
guarantee that the special starter will always be exactly the same as
it was when you first got it.

The best technique is to establish a source for the starter in the
area where it originally came from.

Aside: At this time, most home-drying methods are only successful
some of the time ( more successful sometimes and less successful
other times. "Successful" means the dried starter is restorable to
an exact duplicate of the original ( in flavor and other
characteristics. Failures usually raise dough ok, but lack the
sourness of the original due to the lacto-bacillus cultures dying
during the drying and storing processes. Drying and storing
sourdough starters is still somewhat of a new science. Sourdoughs
International (SI) has figured out the process, but for business
reasons must keep it proprietary. Other commercially available dry
starters that I've seen, including a popular one (with tourists) that
associates itself with the gold mining industry, are complete
failures. To my knowledge, the best ways of storing sourdough
starters (without needing feeding and care) include the drying of
starter that is past its prime, and the blending of liquid starter
with glycerin, then freezing. Wild yeasts actually change state when
frozen, and are able to withstand it better. But freezing
temperatures are a harsh environment for lacto-bacillus and it slowly
dies off while in the freezer, hence the bland tasting starter that
you get from a failed attempt at starter storage. For this reason,
it's also a better bet to allow your starter to ferment past its
primer prior to freezing. The yeast may have suffered some, but
that's ok. It'll bounce back when it finds itself back in a good
environment. And going 'past prime' with the starter tends to
maximize the concentration of the lacto-bacillus, resulting in a
larger population and better odds going into the freezer. Blending
the starter with glycerin helps protect the cell walls of the yeast
and lacto-bacillus from the damage that occurs during freezing and
can also result in successfully stored starter.


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