I accidently activated a package of “Wyeast 1272 American II” four months ago. The mfg date is 29 May 12 (5 months, 1 week), and its been stored in the refrigerator all the time. The package is still swollen. I intend to use it for a HALF batch (2.5 gals) of American style Ale.
Question: Can I get away with simply pitching the ENTIRE package into the half batch, letting the batch size compensate for its age and swollen state, or do I really need to do a starter? I’ll do a starter, but would simply prefer to simply pitch the whole package and call it good.
Of course, what I prefer doesn’t matter if the only viable solution in this situation is to do a starter. I just don’t have enough experience to know yet. The FAQ on the Wyeast website says its OK to delay use on an activated package, but I don’t think they were talking about a four month delay. But their advice is based on a full batch.
Again this wouldn’t even be a question if I was doing a full batch - a starter would be a no-brainer in this situation. But I’m assuming the half-batch size is the key to the answer. Thoughts?
I would do a small starter on a 4 month old smack pack either way. It might work just fine but why take the chance. Mix up a 1 qt. starter and give it a 2 or 3 days to get ready to go. That way you know it’s good to go.
I am not sure that activating the pouch matters so much here. Plug your numbers in to mr malty and see what it says. Maybe plug it in as 125ml (or whatever) of harvested dregs with the harvest date at the 4 month mark? The fact that the pouch is still swollen means nothing, it is sealed and the co2 was released. It’s not going anywhere fast.
You could pull off a pint or so of your wort or make a simple starter early on brew day and pitch the pouch into that. you should see some activity by pitching time if the yeast is still good. Plus it’ll give the buggers a boost.
I’m not exactly a yeast expert, but it’s my understanding that bringing yeast out of hibernation with a small amount of wort means they won’t be able to rebuild their reserves for extended storage. That would mean activating the pack weakened all the cells and then they were stored for 4 months with no food. If this is true, then 10% viability is definately a best case scenario.
A brand-new pack (100 billion cells) would be about right for 2.5 gal of average-gravity ale. The rule of thumb for refrigerated storage is 25% viability loss per month, so after five months it should be in the neighborhood of 25% viable - 25 billion cells left in the pack. I doubt that smacking the pack made a huge difference either way. I’m sure it will ferment just fine if you pitch the pack, but a 500-750 mL starter would get it back to the proper cell count.
Just wondering. I use Mr.Malty and/or Yeastcalc for these type questions and both have a 10% viability at 5 months. Where does the 25%/month rule of thumb come from?
The MrMalty calculator assumes that viability drops linearly from 100% to 10% over a period of ~3.5 months, then stays at 10%. Which is obviously a very artificial-looking curve, but probably close enough not to cause any problems until you get to very old samples.
Who originated the 25%/month rule, I don’t know, but it does track well with cell counts I’ve done on stored slurry.
