Anyone know how to step up frozen yeast and make a starter?

[FswBG]

Resurrecting old comments here:

It‘s my understanding that you don‘t want/need to let each step ferment out if you‘re propagating, i.e., trying to build up cells. The growth phase is only at the beginning, and AFAIK is usually done in about 24h. You get much better growth if you can keep the yeast in respiratory mode, i.e. not fermenting, which can be (partially) achieved my maintaining enough oxygen and having enough FAN. Yeast in the correct conditions have a doubling time of about 90 minutes. After the exponential growth phase you can/should step up, AFAIK.

Can anyone confirm or refute this?

Not really refuting you on it as I know people that do it that way and have no issues. The reason I prefer to chill and decant is to reduce the spent oxidized beer from propagation. At the same time it's removing leftover trub, esters, and other fermentation biproducts that could impact the flavor of your beer. There's also the thought that there would be benefit to the yeast having already gone through a stationary and cleanup cycle. It would have the advantage of being fortified metabolically with thicker cell walls and more glycogen reserves. Trying to guess at peak log phase when to pitch could impact both your pitch consistency and compensation of OG calculations in my mind.

When slanting or stepping up from a frozen stock I follow this member's method

 

[joshbuhl]

Not really refuting you on it as I know people that do it that way and have no issues. The reason I prefer to chill and decant is to reduce the spent oxidized beer from propagation.

Not letting it ferment out is not the same as not decanting, which I definitely do for the same reasons...don't want a liter or more of thoroughly oxidized "beer" in the product!

There's also the thought that there would be benefit to the yeast having already gone through a stationary and cleanup cycle. It would have the advantage of being fortified metabolically with thicker cell walls and more glycogen reserves.

My understanding is that they build up these reserves, etc., in the lag phase and that these get spent in the stationary phase, so you'd actually be depleting reserves, AFAIK. (can someone please knowingly confirm or refute this?)

Trying to guess at peak log phase when to pitch could impact both your pitch consistency and compensation of OG calculations in my mind.

If you always step up after 24h, that'd be consistent...do a cell count after 24h and if you've hit 2x10^8 cells/mL, step up.

All that being said, my goal is not to step up at all, but pitch the thawed frozen yeast sample into a fortified 1 Liter starter two days before brew day, have enough cells after 24h, cold crash so that I can decant and pitch on brew day. I also just don‘t think spinning it for a week is making healthier cells.

The difference between these two ideas/approaches is exactly what I'd like to hear somebody who knows it for sure to school us on... Any takers?

 

[joshbuhl]

When slanting or stepping up from a frozen stock I follow this member's method

Just watched the vid, which was interesting (and got me thinking about getting a bottle of oxygen…)

Do you know what the idea is behind adding ascorbic acid to the cryopreservative? I follow the method described in detail on Homebrew Notes, and haven‘t heard of adding ascorbic acid before.

 

[FswBG]

Just watched the vid, which was interesting (and got me thinking about getting a bottle of oxygen…)

Do you know what the idea is behind adding ascorbic acid to the cryopreservative? I follow the method described in detail on Homebrew Notes, and haven‘t heard of adding ascorbic acid before.

Yes, Ascorbic acid is generally used as an antioxidant to extend the shelf life. Especially when banking since glycerol will oxidize over time. It also benefits by scavenging ROS, neutralizing free radicals before they can damage the yeast cells.