Expired Dry Yeast

I was searching the nets the other day for info on using expired dry yeast, and didn't come up with much (might not have searched enough?) This past Sunday, I used a pack of safale s-04 that was about 1 year past the expiration date, and fermentation took off just like expected in about 24 hrs. Seems to be working fine? Just wanted to share that in case it useful for others.

I will check the attenuation in a couple weeks.

The typical problem for old dry yeast is viability percentage drops over time by a variable amount so it becomes hard to tell if you are pitching a sufficient amount for your batch... It will usually make beer (and I keep expired yeast for repitching emergencies too) but you may get some off flavors from stressed yeast - or not...

I'm actually starting to wonder if I'm using too much yeast when I pitch a pack of S-04 into a Bitter or Mild (OG < 1.040). I think you get more ester production when under-pitching, right?

So you might notice a more fruity character if the viability went down low enough.

If the yeast is too old, just toss it into the boil in the last 10 minutes, and use it as yeast nutrient. That's better than worrying yourself over wondering if it will kick off the fermentation or not.