Expired Yeast Taste & Smell

[tjashing]

I've seen multiple posts that expired yeast can still be good past its expiration date, but not too many on how the yeast should taste and smell.

What should healthy yeast smell and taste like, and how to know if its gone bad?

I have 2 packages of the white labs purepitch yeast, packaged mar 2017 & best before sept 2017. I'll be brewing with this yeast mar 2018 (26% viable cells - so I pitched 2 packages with a a 1L starter). When I opened the yeast, it looked like any other liquid yeast, smelt ok but sort of had a sour taste. Is this normal for liquid yeast (I've never actually tasted liquid yeast before, so not sure if this is typical.

I'm wondering if its worth pitching this yeast starter or buying new liquid yeast packages?

 

[Jayjay1976]

What you've got yourself there is a GILF yeast. The taste/smell of the yeast won't tell you much about it, you need to ferment a batch with it to evaluate. Even if there are only a few hundred viable cells left, they will cannibalize the dead yeast as nutrients to multiply, then ferment your beer much as fresh yeast would. The quality of beer produced on a very high level might be variable, but you will still end up with very tasty, drinkable beer. Maybe grow a 2l starter or brew a 1 gallon batch as both a test and as a step-up to attain proper piching population, then go for a full 5 gallons. I never toss old yeasts, they are tough lil' buggers.

Edit: It's been stored in a fridge, right? If you've at least stored it cold, it will be just fine. That's $16 worth of yeast there, don't toss it out.

 

[tjashing]

Thanks for the reply. The yeast was refrigerated and our batch size is approx 3.5Gal - which is why I went from a 1.5 L starter to a 1L starter. I could add some more DME if no activity starts.

 

[Jayjay1976]

Thanks for the reply. The yeast was refrigerated and our batch size is approx 3.5Gal - which is why I went from a 1.5 L starter to a 1L starter. I could add some more DME if no activity starts.

It might lag for a few days before krausen is evident, but that's okay. My first AG batch (a 1 gallon kit) took 8 days to show any activity. Dry yeast sachet was 12 months past it's expiration date.

 

[BitterSweetBrews]

I just used some s-04 yeast I harvested in Feb 2017. 3 pints, stored in the fridge all year. I decanted the liquid, swirled up the dregs and pitched all 3, without making a starter, into a 3 gallon batch. It was bubbling right along after 18-24 hours. As was said before, those little buggers are tough.

 

[65C]

5 month out of date, kept reasonably well - it'll be just fine

sometimes can be slow to kick off so worth doing a starter if you've time

there is so much FUD about old yeast and about quantities required to make a brew

I've made sourdough for years - sometimes I've lost interest for months and have had to revive an old crusty/mouldy bit of yeast scraped out of the bottom of the old starter pot in the fridge - a teaspoon of the soft stuff under the red furry mould - a couple of feeds - and it's good as new

one of my current brewing yeasts (a Ringwood) is on it's 10th batch - still as good as it was when it was first pitched - four of them were back-to-back on the yeast cake without washing the carboy

I needed to do an extra brew a few weeks ago and had no yeast kicking around - but I found an old packet of BRY-97 - I hydrated for 20 mins and dropped straight in to an 8% - was fine