"Allen Cohn" <allen@cohnzone.com> wrote :
>Here's another way to justify using start just at the same point
>when one would normally refresh it:
>
>When one makes bread using yeast, one measures it out so that you
>consistently have the same number of yeast cells in the dough. By
>using the sourdough starter just at the refreshment point, one can
>have the same confidence that one is putting the same number of
>yeast and bacteria cells in.
Actually, I wouldn't, and don't, do that. First a bit of background
information that might seem unneeded.....
There are a number of cycles after the feeding of a starter. How
long each cycle lasts depends in many factors, such as the culture,
the hydration of the starter, the temperature of the starter, and the
vitality of the starter.
All cultures are, to some extent, different. Some are faster than
others. A higher hydration, or wetter, starter tends to work more
quickly than a thicker one. Lower temperatures reduce activity
levels, higher ones speed things up - up to a point. And a starter
that has been in storage will be sluggish, and not just due to it's
temperature.
First there's a lag phase as the critters start to digest the food
and multiply. This could be as little as a few minutes or it could
be several hours. During this time, the starter looks like it's not
doing anything. As an old physicist's joke has it, "I may not look
like I'm doing anything, but at a subatomic level, I'm a blur!"
Then there's a growth phase, where the dough (or starter)
rises. This can take an hour or five or six hours.
Then there's a plateau where the tendency for the dough to collapse
and the effort of the starter's critters to make it rise are
balanced. That's where the starter has reached it's peak and stays
there for a while. This is usually a number of hours, and as many as
5 or 6 with a thicker starter.
Then there's a decline in the activity level of the critters and the
starter recedes, or collapses. This can take hours, or longer. Many
starters will take about 8 to 12 hours to go through the cycles and
wind up at the same level as when they were fed, assuming 100%
hydration, a healthy starter, and room temperature.
Then there is a period where the critters slow down and start to die
off for lack of food.
If the previous phase is extended enough, unpleasant things will
happen. Among them, your starter could die or develop unpleasant
behaviors if you try to revive it. When teaching classes, I tell my
students a starter is a living thing, like children or pets. If you
don't feed them for a while, they get cranky. If you don't feed them
for long enough, they die. So, feeding them often is important.
We usually feed the starter when it is into it's decline phase,
largely to keep from winding up with too much starter, or starter waste.
However, I have not found that to be the best point at which to USE
the starter. I like to use the starter when it is at it's peak and
before it declines. When you make dough, it goes through the same
phases as a starter when it is fed. If your starter is already in
decline, the lag before the dough starts to rise is extended. The
bread making process is more predictable when you use the starter at its peak.
A lot of the work I've done with sourdough has the goal of making it
predictable. When I started, sometimes the dough would rise quickly,
other times it took a good while, and other times nothing
happened. I knew that the bakeries that used sourdough couldn't
afford that sort of inconsistency, so I read and experimented to get
a more stable process. And for me, that means using the starter when
it's at its peak.
Mike