The sourdough stuff I promised in the last post hasn’t gone too well so far. I made the plates I mentioned but doing things with them has not gone well.
The idea is to do a few things:
- Compare the organisms in three sourdough starters
- Evaluate the properties of the yeasts I can isolate
- Try to learn a thing or two about lactic bacteria
- Try to cultivate a new starter (the third from above) from scratch, which I hadn’t done in a while
So the fourth bullet is sort of working, but not without some problems. I made an effort to use sanitized glasses and silverware to handle the starter so that I could be reasonably sure the organisms were coming from the flour and not from my environment. It took a long time but I can’t say whether that is due to that or some other reason. After a lot of strange stages (producing what I think is DMS, since it smelled a lot like cooked corn) it looks like it is becoming a viable starter. However, I messed up one day and stuck an unsanitized fork in there. It was just starting to turn around, but it sped up its turnaround after that. Having recently worked with other starters it could be I “contaminated” it with known-good organisms.
(As a side note, I always wonder if the number of environmental bugs is sufficient to overcome whatever is in the flour, but I suspect that is highly complicated and not subject to a simple yes/no assessment. I wish I had access to irradiated flour so I could put it to some sort of test.)
The first three require me to plate the starters. My first effort at this was destined to fail: I tried to streak after dipping a needle in the starters. I got some bugs from the early 2nd day stage of my new starter, some bacteria I can’t identify (yellow colonies on PDA). The other plates grew only a handful of yeast colonies but the plates grew tons of mold before I could do anything else with them. In any case, the bits of liquid dough along the streaks made it quite difficult to tell if things were growing at first.
I repeated the effort this unplanned long weekend, since I was home from the storm. I went with spreading a sample of sterile water that had a bit of starter dipped in it. After 24 hours there is no growth at 75F. We’ll see what happens in the next couple of days.