Hi!
Slow yeast is just my feeble attempt to describe regular yeast - coarser
granules that are slower acting than the finer granules of "instant" or
"rapid" or "bread machine" yeast. I think I remember reading somewhere that
the temperature of the drying of the yeast is different - higher temperature
and more organisms killed in regular yeast? My mom baked bread regularly in
the 70's and going back to baking in the 90's, learned that yeast has
changed; it's been bred to be faster and stronger. Even the regular yeast
is faster than it used to be (same source of wheat she grinds for the flour,
etc. - this was the only difference she could determine). At the food co-op
I use, the bulk yeast in the cooler IS coarser than the regular yeast in the
jars at the grocery store (Fleishmann's, Red Star). I use this yeast for my
whole-grain breads, and the instant for my quick, sandwich breads.
Dulcey