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.


  • 1
    This is why I keep a few packets of various dry yeasts in my fridge.
    – baka
    Commented Sep 4, 2012 at 19:24

2 Answers 2


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.

  • Thanks Denny. As for the smack pack, it seemed to swell slightly but I can't be sure it was actually going; I should have done it the night before and confirmed a really swollen pack. The previous time I'd done that it swelled so much in 24 hours that I was sure it was going to burst. Tasting it is a good idea. I've never had this happen before, so I'm surprisingly lost, despite the number of brews I've got under my belt.
    – cswingle
    Commented Sep 4, 2012 at 17:08
  • You have done enough brewing that I can give you my favorite piece of advice....deal with it! :) You know how things work and your ideas were good. All you need to do is apply your knowledge and experience to the situation and make your best guess. That's what any of us who advise you are doing!
    – Denny Conn
    Commented Sep 4, 2012 at 19:39
  • More fun to deal with it here with your online buddies who can feel your pain and maybe offer an idea you didn't think of. Talking to my wife about such matters is like talking to a wall!
    – Dale
    Commented Sep 19, 2012 at 23:57

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.

  • mdma, Thanks. Tasting it before re-pitching (should that be necessary) is an excellent idea that oddly didn't occur to me. Good to know 1084 is slow. The last time I used it was 1994, and I pitched at 80 F, so it probably took off back then.
    – cswingle
    Commented Sep 4, 2012 at 17:20

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