commercial bakers yeast starter vs. sourdough starter
I got interested in using a starter for breadmaking several months ago. I sent for a good sourdough dry start through Friends of Carl (Oregon Trail Sourdough) and while I was waiting for it to arrive set myself up to learn the process using commercial bakers yeast. I use regular dry yeast, not instant dry yeast.
I was very happy with the result! It worked well for a long time, until suddenly it didn't. My yeast starter started going down and finally dying. I had to re-start the starter from scratch 3 times, each time it lasted a shorter period of time.
I think I thoroughly understand the requirements of proliferating yeast. I've read widely on this site and elsewhere. What I'm wondering is this, and this is my question today -- could it be that keeping the starter in the refrigerator is part of the problem? I bake only 2 - 3 times per week, so I keep the starter in the refrigerator, taking it out overnight to refresh before baking day.
Although, come to think of it, sometimes I don't do this. Sometimes I decide to bake in the morning and just remove a cup of starter for my bread, refreshing the starter and returning it to the refrigerator after an hour or two. Is this part of my problem?
The commercial yeast starter was wonderful when I first set it up, very tangy in smell and taste, very bubbly and active after refreshing. But the new starters have never been that good, even though I am careful about hygiene/prevention of contamination/using a perfectly clean mixing bowl and cover. I experimented with different kinds of covers and I use glass bowls.
Any insight would be appreciated. Now that I'm having this kind of trouble keeping the commercial yeast starter going I'm afraid to start my sourdough. I've had the dry start from Friends of Carl for several weeks and I don't want to waste it if I don't have my technique down right.