Roy,

Thank you for the informative and in depth response. I have loaned my
copy of Reinhart so I cannot confirm that I have attributed him
correctly. For the moment let me strike the offending reference to
malolactic.

The "sense" of Reinhart's information is that beneficial enzymatic
activity occurs during the retarding period. This activity converts
additional starches to sugars which are then available further
fermentation.

Perhaps there are Reinhart fanatics out there. I hope I haven't
offended them either.

Will

Begin forwarded message:

From: (Roy Basan)
Date: Sun Feb 22, 2004 6:23:01 PM America/Chicago
To:
Subject: Fwd: Sourdough bread/starters

William Waller wrote in message
news:mailman.45.1077468308.204.rec.food.sourdough @mail.otherwhen.com.
..
There's quite a bit going on during that cold cycle in the
refrigerator. I would recommend reading Peter Reinhart's chapter on
cold fermentation in
the "Bread Baker's Apprentice" for the details. He offers a good
discussion on the enzymatic processes that accompany fermentation.
Very
briefly, there is malolactic conversion of flour starch to sugar
occuring. When the dough is removed from the cold these newly released
sugars are available for additional fermentation. Net result...
additional flavors develop.

Malo Lactic fermentation?
Allow me to analzye the proposition (in chemical terms to be
precise).
That chemical reaction happens spontaneously only in wine making.
What is meant here simply is the malic acid which is a regular
component of fruit acids but absent in cereal produced acids is
converted to lactic acid by the Leuconostoc and pediococcus species,
sometimes by the lactobacteria.
But based on experiments usually the two leuconostoc and pediococcus
as the culprit. In particular leuconostoc oenous. For more
information, look at a textbook about industrial fermetation and
industrial microbiology.
This is a complex chemical reaction with varied pathways of its origin
and several enzymes take part in this process
To make it simple,
Before that We have to remember first that malic acid is the
predominant acidulant in green apples. But we do not add apple juice
in sourdough nor use apple puree as part of the fermentation for
sourdough either.
Indeed in some rye flours their are infinitisimal amounts of malic
acid but they vanish during dough making amd baking.
I don't think that the offending organism can convert that to lactic
acid as malo lactic fermentation occur after alcoholic fermentation(
or the enzymatic reaction of sugars to alcohol.
But in any bread fermetation their is no such endpoint.EVen if the
dough is overproofed alcoholic fermentation is still existent.
I do not see the reason (or even evidence) that the sourdough organism
can syntheze malic acid either from carbohydrates..

Anyway,
The chemical reaction comes out like this:
COOHCG2-CHCHOH-COOH( malic acid) ---- COOH-CHOH-CH2(lactic acid) +
CO2
The net effect of these is that the malic acid being a stronger acid
is into weaker lactic acid which results in the change of taste of
wine ( usually most detrimental and in some wines beneficial) .Even
in this case it does not affect flavors.
How does this malo lactic fermentation occur?
It is usually during the end of the alcoholic fermentation of wine in
the presence of offending bacteria that may have contaminated the
wine yeast used.
( or purposely added if the malo lactic fermentation is desired).
Supposing the soudough starter is populated with a series of
lactobacilli. L. Brevis, fermenti, diasticus,San francisoc, etc, and
they have the minimal capability to convert malic acid; but where
they can find such acid to convert enyzymatically?

Another thing there is an antagonism between the yeast and the
leuconostocs oenus. Yeast will usually predominate.
And even if both of them are present it is likely that effective
conversion by the sleuconostoc could occur as the population growth is
hindered as well as the deteriorative enzymatic activity.
Besides what are the components of bread flavors that are
distinctively found in the sourdough?
It is usually pyrazines,pyrolles,furanones, lactones,
aldehydes,ketones, and esters.
If we have to consider the latter in particular as ethyl maleate
which is the result of the reaction of malic acid and alcohol.
I have looked into the list of flavor components for sourdough (
Fenaroli's Handbook of Flavor Ingredients by CRC press ,volume 2.
but I could not find that ethyl malate or diethyl maleate ( the
possible result of the reaction(esterification) of malic acid and
ethahol)is found in it in the esters section of the sourdough flavor
components.
There is ethyl lactate and ethyl acetate but nowhere is that malic
acid derivative found.
How did Reinhart reach such a strange conclusion?

BTW,I am sorry If I offend some die hard Reinhart fanatics here.
Roy
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