White Labs WLP001 stored incorrectly - can I still use it?

[thj]

Hi,

I'm planning my first brew, but unfortunately I stored White Labs WLP001 at 73F for a day and a half before putting it in the fridge.
So the question now is if I can still use the yeast, or if it's dead. How fragile is it?

Thank you!

 

[jack13]

73 degrees for a couple days is fine. More important is the manufacture date. It should be on the packet somewhere. The link below will give you an idea of how many of the 100 billion cells are left (enter date second blank on send line). You can also enter other info if you'd like.

http://www.brewunited.com/yeast_calculator.php#

 

[thj]

73 degrees for a couple days is fine. More important is the manufacture date. It should be on the packet somewhere. The link below will give you an idea of how many of the 100 billion cells are left (enter date second blank on send line). You can also enter other info if you'd like.

http://www.brewunited.com/yeast_calculator.php#

Thank you very much. The yeast is manufactured 04-13-2019, so that gives a viability of 39%. Is that okay?
I'm brewing 2,5 gallons (10 liters).

 

[jack13]

You'll get all kinds of thoughts on this, but my opinion is that if it's not a high OG beer you'll be OK with a half batch.

 

[Staticsouls]

Make a yeast starter and find out. This will likely be the best way to tell. The other thing about that is if the yeast count is a little low, the yeast population will increase with the starter.

 

[kh54s10]

A pack/vial is approximately half of what you need for a 5 gallon batch when fresh. Some, including the manufacturers say that a pack is plenty. This is questionable.

So, IMO, a fresh pack would be the right amount for your 2.5 gallon batch, but with 39% viability I would say you only have 39% of what you need.

I always make starters when using liquid yeast.

But in answer to the question, sitting at room temperature for 1.5 days is not a problem.

 

[jack13]

Make a yeast starter and find out. This will likely be the best way to tell. The other thing about that is if the yeast count is a little low, the yeast population will increase with the starter.

The yeast population will definitely increase with a starter, but doing this would not tell him if using only the yeast pack he has in-hand would have been enough.

 

[Staticsouls]

Only a microscope and someone who knows how to count yeast could.

 

[deadwolfbones]

It will make beer. Pitch it and see what happens (unless you have time/the equipment to make a starter).

 

[thj]

I pitched it, and there's activity. Time will tell if it's enough
Thanks for your thoughts.