I'm new to this list and missed the start of this discussion, but can't
resist a comment about starter cultures.....I've worked in quite a few labs
where we worked with yeast and bacterial cultures, and we never had any
trouble with contamination from the air. The flour, the water, and the
utensils would have a lot more effect. If you want to rigorously maintain
a sterile culture, you have to autoclave everything it touches or that
touches it--in the lab, this means autoclaving the broth you grow the bugs
in before you add the culture, which would do your flour in the starter no
good at all! I don't think it could possibly be worth the hassle of
sterilizing the equipment (and BTW, 20 minutes in a pressure cooker at 15
psi (1 atm) is a pretty close approximation of a typical lab glassware
autoclave cycle) before adding the necessarily non-sterile flour, unless
you were going to maintain a liquid culture--and maintaining a mixed (yeast
and bacterial) culture would probably be a lot more difficult in straight
liquid culture.
Diane Brown
brown_d@kids.wustl.edu