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Q: Saccharomyces exiguus ( Answered,   0 Comments )
Subject: Saccharomyces exiguus
Category: Science > Agriculture and Farming
Asked by: ddemuth-ga
List Price: $5.00
Posted: 02 Mar 2003 11:45 PST
Expires: 01 Apr 2003 11:45 PST
Question ID: 169612
Saccharomyces exiguus is the wild yeast used to make classic San
Francisco sourdough bread. this spore grows/lives in the wild, and
only in a specific region, ( the S.F. bay area) due to climate,
weather conditions, geography, etc. My QUESTION is; what is the Exact
Regional boundries where this yeast will grow, from (north) to
(south), and (east to west)?
Subject: Re: Saccharomyces exiguus
Answered By: chromedome-ga on 02 Mar 2003 20:20 PST
Hello, Ddemuth-ga!

I am an avid reader of all things food-related, as befits a cooking

Just two nights ago, I came across a tolerably full treatment of this
very question in renowned chef/educator Madeleine Kamman's book "The
New Making of a Cook" (William Morrow & Co, New York, 1997).  You
should be able to find this work at any larger library; it is a
revision of her 1970 classic "The Making of a Cook."

The short version is that S. Exiguus (which co-exists in a symbiotic
relationship with Lactobacillus San Francisco, in the classic SF
starter) thrives best in temperatures of 50-65 degrees Fahrenheit, and
is partial to a moist climate.  San Francisco, with its cold fogs,
offers these organisms an ideal home.

While S. Exiguus will go on cheerfully working in other regions during
colder months, local strains of Saccharomyces will usually take over
as the weather warms up.  This will result in a frustrated baker, and
loaves without that characteristic San Francisco flavour.

So, your question does not readily lend itself to a purely
geographical answer.  You might live relatively close to San Francisco
and not have a suitable microclimate; or you might be hundreds (or
even thousands) of miles away and be successful.  In her book, Kamman
comments that Oregon, Washington, and Alaska all offer numerous
microclimates similar to that of San Francisco.  She has had success
herself in maintaining a culture of S. Exiguus in the French Alps!

By contrast, at her current home in the Napa Valley, her S. Exiguus is
only viable during the winter months, when the SF-like cold fogs roll

Don't despair, though!  If you do not live in an area that is blessed
with cool, damp weather year-round (he said, tongue in cheek) there is
an alternative.  The vegetable bin of your refrigerator provides a
suitably controlled environment and can be used successfully.

There are a few niceties to the process.  Because of the unusual
acidity of S. Exiguus cultures, you will need to use a high-protein
bread flour to get best results.  For the full procedure, see pages
1050 & 1051 of "The New Making of a Cook" (page numbers given are for
hardcover edition).  I will not reproduce it here in its entirety
because of the copyright issue.

The book is well worth owning, by the way, if you have any serious
interest in cooking.  Madeleine Kamman is one of the few French
chefs/food writers who can approach the subject in a relaxed and
humorous way.

When you set about making your own bread, you may wish to visit Joe
Jaworski's website, which includes an excellent illustrated
introduction to sourdough breadmaking.  You will find it at this link:

San Francisco and other regional sourdough starters may be purchased
online from Sourdoughs International, at this link (proprietor Ed Wood
has a book on the subject):

Search strategy

The bulk of the material above is derived (as noted) from Madeleine
Kamman's book.  The balance, and much, much, more; may be found by
searching on the following keywords:

"San Francisco" +sourdough
"s. exiguus"
"sourdough starter" +purchase

Thank you for an interesting question (I could talk about food for
hours).  I hope we'll be seeing you again.


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