[Sca-cooks] German Breads

[Dragon]

Terry Decker wrote:

> > 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.

Commercial yeast are grown in molasses, they are adapted for using 
the easy food they get from sugars and don't do well in the long run. 
The wild yeasts are adapted to a different food source (the grain).

>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.

I've found that the key is maintaining a healthy starter, the problem 
is that to do so requires a lot of attention to keep the starter 
properly fed and happy. It's not a lot of work but it does require 
regular attention several times a day. The main issue is that 
detrimental byproducts of fermentation build up and inhibit the 
activity of all the microorganisms in the starter. Combatting this 
requires that the starter be fed regularly with a lot (relative to 
the inoculating culture) of new flour and water. The instructions 
given in most recipes are ridiculous in terms of both quantity of 
ingredients used and the feeding schedule and are just about 
guaranteed to produce a less-than-optimal starter.

A lot of the instructions out there deal in CUPS of flour when 
feeding a starter. This is absurd for the home baker, you really only 
need a small amount which is a lot easier to feed and maintain than a 
large crock full of wasted flour. When I was baking regularly, I 
never had more than 1/2 cup of "mother starter" around at any given 
time, it was usually much less than that. My starter was so active 
that I had to put it in a container 10 times its volume when feeding 
it or it would blow out over the top. As I no longer have the time to 
devote to this, I have not baked sourdough in a long time.

This particular starter was begun by simply adding a teaspoon of 
water to a teaspoon of flour. It got fed every 8 hours in the first 
week, after that I was feeding it twice a day. I kept a tablespoon of 
each ripened batch and got rid of the rest before feeding it again 
with 1/4 cup of flour and water slurry (100% hydration). This 
resulted in an extremely active starter after about 3 weeks. I never 
had to supplement the dough with commercial yeast when I used this starter.

> > 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,

There has been a lot of argument over this in the sourdough community 
and the scientific arena. However, at least a few of the 
microorganisms (and possibly the yeast that occurs naturally in 
flour) appear to produce amylase (a starch degrading enzyme) and 
maltase (an enzyme that breaks down complex sugars to simple sugars). 
Though it is possible that these enzymes are also of plant origin and 
may occur in the grain naturally, they definitely are produced in the 
grain if it is germinated (that's part of the reason for malting 
grain, to make these enzymes available for mashing and brewing).

>nor does it usually grow on the
>grain kernals.  If they did, they would attack the flour immediately after
>milling.

Yeast require a relatively large quantity of water to survive in 
their active state, there is not enough moisture for this to occur in 
the grain or the resulting flour. Even with relatively "green" grain.

>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.

Yeast are anaerobic organisms, they do not require oxygen except for 
reproduction. While you feed a starter, a sufficient quantity of 
oxygen is usually mixed into the slurry to enable the synthesis of 
protein and the budding of new yeast cells. Once they enter the 
fermentation stage, the yeast can survive just fine without oxygen.

>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.

This is relatively consistent with what I have read.

>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.

I understand the concept. I fervently believe it is wrong. For one 
thing, lactic acid does not have the sharp sour taste a lot of people 
associate with San Francisco style sour dough, that is actually 
derived from acetic acid.

In fact, to understand the difference, the slight sourness in a 
product like salami is from lactic acid (the product of the 
conversion of lactose to an acid), it is mild and unobtrusive and it 
does not smell sour. The sharp acidity of vinegar is from acetic acid 
(the product of the conversion of ethanol to an acid).

And I contend (and empirical evidence confirms) that lactic acid is 
produced without adding milk products. The Ph of a properly fed 
starter is quite acidic without the addition of any extra lactose.

>Most lactobacilli don't produce the sour taste of Lactobacillus 
>sanfrancisco (or L.
>sanfranciscensis, if you prefer).

There are essentially two main classes of lactobacilli, 
homo-fermentative that produce only lactic acid and 
hetero-fermentative that produce both lactic and acetic acids. The 
exact balance of acids produced by the hetero species is very 
dependent on temperature during the fermentation.

The species designations of all the different strains is somewhat 
cloudy and probably won't be sorted out until somebody takes the time 
to do genome sequencing of various cultures.

Bottom line is that the sharp sour flavor in San Francisco sourdough 
(something I an not a huge fan of) is from acetic acid in combination 
with the lactic acid.

>Recipes that call for the addition of
>sour cream or vinegar are trying to add a sour flavored agent to the
>starter.

Personally, I don't care for such recipes. I like my sourdoughs to be 
plain, simple lean breads without anything beyond the starter, flour, 
water and salt.

>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.

Again, genome sequencing needs to be done to determine if it is a 
unique species, I'm not too hung up on that part of it really. It may 
be unique, it may not. I think the difference in results that are 
achieved have more to do with the way the starters are grown and 
maintained than anything else.

Dragon

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