Wyeast Smack Pack 10 Months Old

[Jer]

I have a Wyeast Smack Pack that is 10 months old... Manufactured May 2015

Although well refrigerated I didn't realise that the yeast cells die off with age and would have used a similar aged pack in my last TTL... which showed no signs of activity (after 24 hours) so I re-pitched with So4

As an experiment I decided to go down the yeast starter route on this next pack... having smacked the pack it took 36 hours to swell... smacked Monday... results on Wednesday... I left in my fermentation fridge at 18 degrees until Thursday and did a yeast starter... for the first time with 1.5 litres of water/dme mix

I have posted a pick today Saturday... looks promising.. an education to me that the yeast smack packs could take some time to swell... patience is a virtue here and of the importance of going down the starter route

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Having got this far I am wondering what the next steps could be... e.g.Could I do a 23L Batch of TTL tomorrow and just pitch from my flask... now I know that fermentation is happening... or am I best waiting for the mini fermentation to finish and chill and decant ready for a brew next weekend?

[Jim]

Interesting experiment. I suppose as long as some cells survive and the pack remains sterile it would theoretically be possible to revive it. However the fewer cells you have the more chance of wild yeasts getting a hold in your starter if you only follow normal home brewing hygiene practices (as oppose to using true sterile conditions as in yeast propagation).

One of the things to watch out for is that even though it survives, the yeast may not behave true-to-type.

[zgoda]

I use such old smack packs on regular basis. The oldest one I had was 24 months after mfg date, that's 18 months past bbe.

Of course I always make starter from any liquid yeast, maybe except for fresh Weihenstephan / wlp300.

[orlando]

Interesting experiment. I suppose as long as some cells survive and the pack remains sterile it would theoretically be possible to revive it. However the fewer cells you have the more chance of wild yeasts getting a hold in your starter if you only follow normal home brewing hygiene practices (as oppose to using true sterile conditions as in yeast propagation).

One of the things to watch out for is that even though it survives, the yeast may not behave true-to-type.

Jim makes some good points here. The moment you open that smack pack the slope starts to get slippery, sanitation is no longer as effective at every stage, sterilisation becomes much more important. With an already compromised yeast pack it becomes even more important. Have a look at aseptic technique to find methods that help to keep you ahead of the nasties. Most of the home brew I try suffers from one or another problem caused by sanitation that is not up to it.

[McMullan]

The yeast are probably not in the best condition, Jer, even if they are showing signs of population growth and fermentation activity. Assuming you didn’t brew yesterday, I’d incubate them at 4*C for 2-3 days (this will help the rehabilitation process) then pour off the spent starter wort and replace it with some fresh wort containing a pinch of complete yeast nutrients. (A match-head sized dollop of Marmite is probably better than nothing at all). Ferment it out then back in the fridge until needed. Pour off the spent wort and resuspend the yeast in some fresh beer wort before pitching. This would maximise your chances of success.

[Jer]

Thank you all for your replies on this one.

I can see where Jim is coming from and will keep in mind that the yeast may not behave true-to-type

I have followed McMullans advice and gone for a second starter step... this time with 1.5 litres of water DME Mix... as per the photo this has resulted in a much more vigorous fermentation... now on the way down

I will follow up in 60 days with how the beer turned out... brew day is probably Monday now... TTL

[npg]

It can be a slippery slope indeed. Without a microscope it's guesswork. You can step it up as if you were propagating from plates, but your viable cell count is a stab in the dark as well as the eventuality of an infection.

What cell count are you aiming for?

[McMullan]

The idea that we have to pitch X cells is a curiosity. The difference between the 'minimum' and 'maximum' must be huge enough not to require any microscopy, in terms of cell counts?