—Yeast does best in temperatures of 100°F to 115°F which is 1-2 minutes in my 1100 watt microwave depending on how much milk I am warming up for this. If you get the milk too hot, you will kill the yeast.
—Use milk that tastes too “off” to just drink, but no chunks; the more sour it smells, the better the bite the sourdough will have.
—This can be left on the counter overnight if you find you don’t have the time to finish it once you started it because something came up unexpectedly, but no more than that.
—All yeasts are pretty much the same: bread machine yeast; 3 pack strips; bulk 2 lb yeast from warehouse stores. It is all in the amount that you use & pretty interchangeable; sometimes you knead more too. I have yeast in the freezer for the last 10 years because I bought in bulk, that still works.
—If in 15 minutes, this starter has not bubbled or foamed up, then the yeast is probably not alive—courtesy of Fleischman’s in the 90’s when I called them because my yeast never foamed up.