Help - Wyeast Viability Question

[Norcs]

Having a look a both Beersmith and the Mr Malty website it is indication that the packet of Wyeast 3725-PC that I have on the way from Craftbrewer will be in no have enough viable yeast (manufacture date of May 2012) for 10L of 1073 SG wort.

In fact it seems that even if I make a starter (wasn't planning on it for 10L), I would need multiple packets.

So I guess the questions is .... is the estimate of only 7-10% viability accurate and if so, am I buggered given that I wont have time to get anymore yeast sorted by Friday.

 

[warra48]

I've always thought the Mr Malty viability figures are pessimistic.

I've used smakpaks as old as yours. Just grow it up, and you should be fine.
I've even grown up a 1/4 split of a smakpak kept in a test tube for 12 months, and it grew up OK.
Just go by your own eyes as you grow up your culture.
I reckon if I have grown 2 to 3 times or more visible yeast, compared to what's in a smakpak, I'm good to go.

 

[mckenry]

Hey Norcs,
The idea of a starter is that you don't need multiple packets.
7% is a fair estimate, so do your starter, you'll be fine. I ran your numbers in yeastcalc and it predicts 1% viability
If you can no-chill, do that on friday still. Make a 2L starter today, ferment it out. Tip the beer off the yeast cake, feed it another 2L and you'll be in the ballpark for cell count. Pitch your cube when the yeast is ready. I normally chill, but no-chill when this kind of thing happens.

FYI - I just fired up an Irisn Ale (Wyeast 1087??? cant remember now) that I split in March 2011 - That's 2 years old.
www.yeastcalc.com - the best IMHO - stated viability 1% - its actually less than 1 by then, but that's the lowest it goes. 3 days later I had a 5L starter, enough to pitch into 53L of 1.050
I had to no-chill this batch as the yeast was slower than I estimated to fire up, but being >2 years old I let it slide...this time..
Yeast is hardier than this board makes you think sometimes.

 

[Norcs]

Thanks for that lads, I will hopefully get the starter up and running this afternoon unfortunately I only have a 1L starter vessel so will need to step it up a few more times especially as I have no stir plate.

I will chill down to pitching temp and leave the fermenting fridge at that temp until I am ready to pitch (I figure Sunday or Monday). Hope it goes alright as I have never given the style a go before.

 

[carniebrew]

3l no name juice bottle is a cheap alternative....