Possible failed ferment: re-boil or campden + re-pitch?

Question

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.

Thoughts?

Answer 1

I vote for #1. First of all, the reason to smack a pack is to assess the viability, not to grow more yeast. Maybe you were already aware of that. Did it swell at all? Your OG was higher than I like to direct pitch, but not so high as to give you real problems. Your wort should still be OK given good cleaning and sanitiation procedures, but you could smell and or/taste it before repitching to confirm that. IMO, pasteurization will affect the flavor and Campden won't really do anything if it's infected.

Answer 2

WY1084 can be a slow starter. On at least 3 occasions has 1084 left me with no visible signs of fermentation for 72 hours, and then it springs into life.

Give it 72 hours and then decide what to do. I'd be very surprised if the yeast really are dead. More than likely you'll see signs of fermentation.

You can use either campden tablets (1 per gallon is sufficient to kill wild yeasts in wine must, but I think that's overkill for a lightly contaminated wort.) The sulphites also help deter oxidization.

Alternatively, raising to pasteurization temperature will do the same job, although you then have the hassle of chilling it again.

Personally, I'd taste it and then decide. If you can't taste any contamination then pitching actively fermenting yeast will take care of any small levels of contaminants in the wort, and pasteurizing or sulphites are not necessary.