On December 23 of last year, I made my usual American IPA. I call it Big Yellow Dog, in honor of my wonderful 110 pound Golden Retriever, Murphy. It is one I created on Beer Alchemy, and have made several times. It calls for one smack-pack of Wyeast 1272-American Ale II. I didn't notice, until brew day, of course, that my yeast was expired by 6 months. I figured, what the hell. After smacking, and shaking, the package began to expand, as usual.
When it came time to pitch (after an otherwise uneventful brew day... hitting all targets perfectly), I poured the yeast in (after the wort had cooled) and noticed a sour smell. Crap! I smelled the package, and it smelled like vinegar. Naturally I was worried. After 3 days, there was no airlock activity, nor any other signs of fermentation (it was in a 6 gallon carboy, for a five gallon batch, so I could see the wort.) I finally pitched a rehydrated package of Notty. Fermentation took off like crazy the next day.
Today (01-13-13) I racked over to secondary to dry hop. My FG was slightly lower than expected (FG of 1.012 vs expected FG of 1.017). But, OK. The smell was fine. When I tasted the sample, however, I felt I could taste a slight sourness. Not quite Belgian Pale Ale taste. Just faint. Could that be from the bad yeast? Anybody ever experience this?
I am going to dry hop 7 to 10 days, then keg it.
Thanks for your help.