Out of date yeast

Clint · Dec 6, 2024

Hello all
As per title...
I'm brewing a dry stout and was originally thinking of using CML Five or US05 however my 2 pkts of CML Five are BBE July 24. My choice now is CML Midland which is BBE Dec 24,so fine. All have been stored in the fridge.
Would it harm to pitch a Five alongside the Midland?

Agentgonzo · Dec 6, 2024

Dried yeast lasts for years. One of my recent brews was yeast that was 6 months after its BBE date and it was fine (I just gave a bit of extra aeration to the wort to give the yeast a helping hand along the way).

> Would it harm to pitch a Five alongside the Midland?
No, it'll be do no harm at all. Both yeast will ferment your brew simultaniously, so you'll get a mix of both characteristics.

Northern_Brewer · Dec 6, 2024

They'll be fine. Dry yeast from the likes of Lallemand and Fermentis has a half-life of a decade or so; once repacked by people like CML they lose a bit of shelflife but I wouldn't worry about a few months here or there,it's really not material.

I've made bread with dry yeast that had spent 20 years on a shelf, no starter or anything just straight out of the pack - it only rose 40-50% of what fresh yeast might have done but it was still alive.

I've resuscitated liquid yeast that was 5 years past best before, with a series of gentle starters.

Clint · Dec 6, 2024

Hmm...might keep them now for a pale after the festivities.

fury_tea · Dec 6, 2024

https://underthejenfluence.beer/urcontent/2017/3/6/i-tried-it-45-million-year-old-yeast-beer

A brewery used a yeast they harvested from the gut of a 45 million year old bee.

I think you might be ok.

Kentish Mike · Dec 6, 2024

When I moved back to the UK and got my brewing stuff back from my dad's attic I found there was a good amount of malt, extract, hops and yeast that had been sitting up there for ~5years...
All was well past it's expiry date and had not been stored carefully.
Rather than toss it, I decided to throw it all in a brew. It actually turned out great, and the dry yeast was fermenting strong on day 2, with no starter.
Made a great beer too :)