Home Bread-Bakers v104.n016.8

Sourdough Seminar

Maggie Glezer <glezer@mindspring.com>
Tue, 23 Mar 2004 22:55:32 -0500
Hello Fellow Bread bakers:

I know that the readers of this digest are very interested in the science 
of bread baking, so I thought I would let you know about a fantastic 
seminar I attended at the Bread Bakers Guild of America in the Retail 
Bakers Association annual convention this past weekend. The Guild organized 
six of the top sourdough experts in the world--a sort of sourdough dream 
team--to speak about the biochemistry of sourdough and to give practical 
baking advice about sourdough baking in "Sourdough: The Science, and Its 
Practical Application in Your Bakery".

I learned a tremendous amount, and thought I would pass on (see below) a 
few of the really juicy but scattered tidbits that I learned at the seminar 
and afterward interviewing the speakers.  For those interested in the whole 
pie, a DVD was made of the talks, and a CD was made of the power point 
presentations, and both will be available soon from the Bread Bakers Guild 
of America.  Contact Gina at gina@bbga.org for more information.

All the best,

Maggie Glezer

PS: Hi back to Michael!

 From Walter Hammes, professor of general food technology and microbiology 
at Hohenheim University in Stuttgart, Germany, who informed me that he has 
been studying sourdough microbiology for 27 years:

During slow, cool yeast fermentations, the extra flavor gained is not from 
the enzymatic release of sugar in the damaged starch granules, which 
happens relatively quickly in the dough, but from a multitude of other 
compounds called flavor precursors released by the activity of yeast and 
bacteria. The flavor precursors become flavors during the browning reaction 
of baking in the crust of the bread.

Some sourdough bacteria are homofermenting, meaning they produce only 
lactic acid, while others are heterofermenting, meaning they produce 
primarily lactic and acetic acid or lactic acid and ethanol, depending on 
the ambient temperature and other conditions.  What I found particularly 
fascinating was that the same amount of lactic acid is always produced, 
while the acetic acid varies.

Warmer temperatures  and wetter doughs favor the development of the milder 
lactic acid (think yogurt) while cooler temperatures and stiffer doughs 
favor the development of the much sharper and more aromatic acetic acid 
(think vinegar).

The balance of lactic acid and acetic acid determines part of the flavor 
profile of sourdough breads.  This balance is called the FQ, for 
fermentative quotient.

Sourdough fermentations have numerous benefits including increasing the 
bioavailability of minerals in the flour, removal of toxins and mycotoxins.

Sourdough breads also have a much improved glycemic index, and do not cause 
the blood sugar to spike and drop as dramatically as ordinary yeasted 
breads. The reason is as yet unclear.

The origin of many sourdough bacteria remains a mystery.  Some of the 
bacteria thrive in nature in extremely odd places, like the teeth of 
children in South America, the human digestive track, or duck's throats. 
Prof. Hammes cannot answer how they find their way into starters, but once 
there, they become extremely dominant and stable.

 From Hubert Chiron, master baker (a real master baker) from the National 
School for Milling and Cereal Industries in Nantes, France:

French customers admire what Professor Raymond Calvel calls a "wild crumb" 
meaning a vastly irregular crumb structure with abundant huge holes.  The 
holes develop as a result of air bubbles in the dough coalescing, and 
forming super bubbles.  To achieve this gorgeous _alveolage_, or crumb, he 
recommends moderate mixing (which is never a problem at home), to prevent 
the formation of too many air bubbles (nucleation); a long thorough 
fermentation (_pointage_), a good rest after rounding the dough, skilled 
shaping, and a relatively short proof (_apret_).