[Sca-cooks] German Breads

[Terry Decker]

> I really do not think milk is EVER necessary in a sourdough starter.
> Nor is commercial yeast.
>

In the long run, I think they are detrimental.   Milk may increase the 
chance of mold infection in the starter.  Saccharomyces cerevisiae doesn't 
do well in the high acid enivronment of a sourdough starter.  A starter 
begun with a commercial yeast can lose potency over time as the acidity of 
the starter kills off the yeast cells.  Additionally, in the acid 
environment, lactobacilli apparently produce a cycloheximide that can attack 
and destroy many organisms, but does not bother yeasts in the genus Candida.

I've made starters with and without yeast and I am of the opinion that 
spontaneous fermentation will produce a better sourdough.  I would reserve 
yeast based starters to places where mold is a problem.  If the spontaneous 
starter isn't as active as you like, the place to add yeast is when you make 
the dough.

> Flour that has not been sterilized contains all the microorganisms
> and the necessary nutrients for them. Add water to the flour, put it
> in a warm place and let it do its thing. It will take a while to get
> going but that is normal, this is not something you can rush and it
> requires a lot of effort to keep a healthy starter going.
>
> The yeast that naturally grows on the grain kernels is very capable
> of breaking down the complex starch in the grain to produce sugars it
> can metabolize. Among the sugars produced by the yeast enzyme are
> lactose and maltose. Both of these sugars are then metabolized by the
> lactobacillus to produce the lactic acid.

The yeast doesn't break down the starch, nor does it usually grow on the 
grain kernals.  If they did, they would attack the flour immediately after 
milling.  Yeast spores settle on the grain and are processed through with 
the wheat into the flour, which is why you can cover a bowl of starter with 
plastic and it will still ferment.

When one adds water to the flour, hydrolysis begins to decompose the starch 
which in turn initiates an amylase reaction converting the starch to maltose 
and sucrose, which are broken down by maltase to glucose and fructose to 
feed the yeast.  The yeast produces maltose, CO2 and alcohol as part of it's 
metabolic reaction, while the lactobacilli produce glucose, lactic acid and 
acetic acid as part of theirs.

>
> Care and feeding of a starter is something that is worthy of a book
> on its own, I won't even attempt to go into it here as I have not the
> time to do it justice. All I can really say is that much of the
> "conventional wisdom" on the subject published in many books is
> wrong. If you really want to get into the vagaries of sourdough and
> starters, I highly recommend starting with the rec.food.sourdough FAQ
> at http://www.faqs.org/faqs/food/sourdough/faq/preamble.html
>
> Now I am not arguing against the use of milk products in the dough.
> They do produce a softer, more tender dough (professional bakers
> classify milk and oils as tenderizers). They can also add to the
> flavor of the dough depending on exactly how much is used. All I am
> saying is that milk is NOT necessary for the lactobacillus strains to
> propagate, the flour contains all the nutrients that the yeasts and
> the bacteria need. Proper feeding, storage etc. are what is important.
>
> Dragon

The idea behind the milk is that it contains lactose, which the lactobacilli 
can convert easily to lactic acid.  Presumably this would accelerate the 
production of lactic acid increasing the sour taste.  Most lactobacilli 
don't produce the sour taste of Lactobacillus sanfrancisco (or L. 
sanfranciscensis, if you prefer).  Recipes that call for the addition of 
sour cream or vinegar are trying to add a sour flavored agent to the 
starter.

I have encountered an interesting statement that I have yet to check out, 
that the yeast in San Francisco sourdough is now named Candida humilis, 
previously C. milleri, and originally identified as Saccharomyces exiguus.

Bear