In article ,
says...

Howdy,

A few days ago, I took out a piece of one of my refrigerated
storage starters, added equal weights of flour and water,
put it aside at 80F, and left it for 12 hours.

When I next looked at it, I was surprised at what I found:

Rather than appearing "frothy" as it always had after this
process, it seems "syrupy" in texture. That texture has
always indicated to me that the gluten has completely
degraded.

There were a few bubbles visible, so some gas was being
generated, but nothing near what I had come to expect. Also,
what little gas was generated, seemed to bubble right out of
the mixture rather than contributing to any increase in
volume.

Next, I tasted a bit of the mixture.

It was quite sour.

snip

Have any of you had similar experiences, and what might have
caused this to happen?

Yeah. Been there a few times. Experience is that wonderful human
ability to recognize a mistake when you make it again.

How long had it been since you last fed the starter?

How often, and how, do you usually feed it?

I found, the hard way, that when I left a starter unattended too long
bacteria that can produce lots of proteolytic enzymes take over the
culture. And they dissolve the proteins in the flour. You can add a
lot of flour and still have a weak dough in a hurry.

If your starter has a strong acetone/cheap fingernail polish remover
smell, that is another symptom.

Sadly, I have not been able to reliably rehabilitate a starter in that
condition. With lots of feeding, the bacteria that just eat starch take
over again, but it is a very tenuous thing. Skip a few feedings, and
the bad guys are back again. If this describes what is happening to
you, it is easier in the long run to discard the stuff and start (or
buy, or get from a friend, or get from the Friends of Carl, or whatever)
a new starter.

Mike