I’m planning a ~1.067 5 gallon IPA Monday and I only have a couple of packs of S-05. The expiration dates are 9/2015 and 11/2015. I wasn’t planning on doing a starter and may not even re-hydrate (older posts when I’ve mentioned this some have said why bother).
Should I use both of these packs? From what I’ve read they are produced 2 years prior. Mr. Malty calculates I should use 2.1 packs. Thoughts?
I could buy new dry yeast, just lazy.
I would re-hydrate and pitch both packets.
Both sachets should be plenty (rehydrated or not [I prefer rehydrating]). Dry yeast is pretty hardy, particularly the cooler it’s stored. You can even store them in your freezer without issues for a very long time.
I pretty much did exactly what you’re planning last week. I brewed a 1.069 IPA and pitched two packs of old S-05 (8-2015). Just checked it last night and it was down to 1.008. Didn’t rehydrate or anything like that. Brewed on 12-9.
Even at that age the packs were probably still 40-50% viable.
It takes years for dry yeast to “expire”. I would use them like normal. The best by dates are bogus.