On Saturday I brewed my 89th batch, an all-grain Irish Red Ale, SG 1.049. Pitched Wyeast 1084 from an "Activator" smack pack dated May 2012 that I'd struck around eight hours earlier, then aerated the wort using a paddle-mixer drill attachment for two minutes. None of these are new procedures to me, although I typically smack the pack the night before brewing instead of that morning (or make a starter on a stir-plate). It's been around 40 hours and there's no sign of fermentation and no drop in gravity.
I will give it another day and a half before I call the fermentation failed and in the meantime will order new yeast from a more reputable source. I probably won't receive the new yeast until Thursday or Friday, so I'm curious about what the best approach is for potentially sterilizing the wort before re-pitching should it come to that. I can think of three options:
1) Don't do anything. Assume the wort is still essentially sterile after one week in the fermenter, pitch the new yeast and aerate again.
2) Pasteurize the wort by bringing it up to around 180 degrees F, chill, pitch, aerate.
3) Add Campden tablets at some appropriate rate, let the wort sit for 24 (?) hours for the sulfites to evaporate, pitch and aerate.