Old yeast

So I went to the LHBS today and got some WLP833 for an upcoming Oktoberfest. I just now noticed that the manufactured date on the package is from January 2016. According to MrMalty, that's 10% viability which has me concerned, also the "best by" date was July 19.
I plan on stepping up the starter to the appropriate cell count. Should I go ahead with it or get a newer vial?

 

I find the yeast calculators to be way too conservative in estimating viability. I did a brew with a 2 year old smack pack, which was supposedly 0% viability. Yes, it took some time to wake up and I had to step it up but it fermented just fine. As long as you don't have to brew tomorrow, go ahead and get a starter going and you should be fine.

The calculators also seem to be too conservative in their estimated growth rates. YeastCalc has a great link to an article by Kai on growth rates with stir plates. His research seems to show that most calculators underestimate growth rates by about half. YeastCalc offers an option to use Kai's calculations for your starter that lead to much higher yeast counts.

The bottom line is you'll be fine with that yeast. Just treat it right.

 

Earlier this year, I resurrected the yeast out of a bottle of 2010 Duvel Tripel, it took about a week for it to fully wake up and start reproducing again. Take it steady, you should be good to go

 

I made a starter from some harvested 001 from 2013 last week. Stepped from 125ml up to 2L over the course of a week (to harvest some more) and it's now fermenting away in a ipa.6 hour lag from pitch to krausen.

 

So essentially, I have no idea how many cells I will end up with and should just pitch it (I'm going to step it up 3 times) as long as the yeast are active.

 

If the yeast is only 10 percent viable on the best by date then it isn't really best by. Someone is in error, either it is Mr. Malty or White Labs. I am using WLP810 right now and it is working though it is past the best by date.

 

I've come to accept that we don't really have a good feeling at all as to how many viable cells are in a pack. Unless it's a pretty new pack and I'm confident that it got to me in good order (whether via mail or from an LHBS), then I assume that there are just enough cells to make a good starter.

If it's 5 million or 60 million, if I make a starter that's big enough based on my lowest assumed cell count, then I'm happy. I don't worry about over pitching, though I'm sure plenty of folks would argue that possibly over pitching by 50 million cells is overkill.

That said, I usually harvest from my starters and save in mason jars, so my cell counts aren't scientific to begin with. I don't know exactly how much slurry I've got, nor do I know the viability of those cells. I just assume a reasonably estimated number and go from there. Hasn't seemed to hurt me yet!

 

The dates on the packages are not "best by dates". They are production dates or expiration dates.

 

That's pretty much the conclusion I came to after a little research. The science is there to estimate cell count but there are so many variables that contribute to the viability in the vial/package. Additionally, if the calculators and literature over/underestimate, we have no idea what we have in terms of cell count, even if conditions are perfect for cell survival. So basically, I'm just going to make a starter for normal gravity beers and step up once or twice for higher gravity beers and lagers.

 

Good idea. The simpler I've kept things, the better my beer has gotten!

 

If that is true then White Labs is mis-representing their product by writing "best by" on the package.

 

Oh, I see. I have never bought one of these new packs. They have changed how they are labelled.

I have never seen a "best by" date on any yeast before.