Yeast viability model and Wyeast smackpack swell time, viability question...

[dusdau]

I used an online calculator to model a two-step yeast starter for a DIPA, OG 1.069. I have two packs of Wyeast 1056 two months old, which the model gave 55% viability.

So that's what I used when designing the starter volumes and getting to where it says I need to be...390B cells or so.

Now...I smacked my packs, put in room at 71-73 degrees or so, and three hours later they seem like they are about to bust.

Should I assume the viability to be 55% still (swelling a tiny pack isn't necessarily indicative of higher viability), or should I perhaps adjust higher given they responded so quickly?? Still leave at 55%?

Thanks for any input.

***EDIT: Based on their site, it seems that a fast swell verifies viability, which makes sense...but not sure what % viability to change calculator to...'65%, 80%, etc. based on huge swell at 72 degrees or so in a few hours'***

Dustin

 

[jdauria]

Don't have an answer how what viability would be, maybe take an average from the two big name calculators out there (MrMalty and Yeastcalc)? Swelling just means the yeast that is viable was eating the wort in the pack.

Just an FYI, when making starters, you don't need to smack the yeast pack, you can just open and add it to your starter.

 

[plinythebadass]

Don't have an answer how what viability would be, maybe take an average from the two big name calculators out there (MrMalty and Yeastcalc)? Swelling just means the yeast that is viable was eating the wort in the pack.

Just an FYI, when making starters, you don't need to smack the yeast pack, you can just open and add it to your starter.

It is a nice insurance policy, you can at least see if there good before you make a starter with them. Plus it's like...a starter for your starter right (i'll be here all week)?

Honestly, I'd say 55% is a very number to model the probability of yeast viability if your getting full swell on your packs within a few hours. My vote would be to inch it up a few ticks closer to 76-81% just to be safe. Even still, this is just a model for your starter, it should take pretty easily. This is tough stuff brewers yeast, it'll ferment fright out of the smack pack but making a starter makes it 10000X times more efficient in the fermentation stage. Basically what I'm saying is, unless your doing a massive beer (barley-wine, imperial IPA) you should be OK making a 1.060 starter and rocking out on your stir plate for 24-36 hours.