200 billion cells pitched into 1.5 L starter - effect on cell count / pitching rate

[pym99]

The Situation:
I've been following Palmer's How to Brew (2017 ed) in making my starters and estimating pitching rates. I make a 1 L starter with 115 g of DME and pitch one package of Wyeast or 100 billion cells. According to Palmer (p 119), 100 billion cells pitched into 1 L of a 1.040 starter will double the cell count. I pitched one packet of 1968 London ESB and let it ferment out at 62-65 F. After 48 hours, I decanted most of the starter, leaving only the extremely compact and flocculated "slurry".

The Problem:
I've made a new starter wort to pitch the 200 billion slurry into, this time 1.5 L of 1.040 wort. My flask is only 2 L so I didn't want to go any bigger and risk blow-off, which would throw off the cell count. Palmer's chart doesn't have a value for pitching 200 billion into 1 L, only 2 L, where he lists a 2.0 growth factor. Into 3 L, it is 2.3, 4 L = 2.6, 5 L 2.8, 6 L 3.0.... However because he doesn't list a value for 200 billion pitched into a 1 L starter, I don't know what the growth factor will be. Palmer says that pitching too much yeast into too little wort will limit reproduction, but there's no formula and I don't know if I can extrapolate down (i.e. 1.5 L = 1.85, 1 L = 1.7, etc.).

Any light you can shed on this question would be appreciated. Thanks!

 

[day_trippr]

Try using the Brewer's Friend pitch rate/starter calculator https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/
You can try pretty much anything wrt starter size and capacity then decide which model (Braukaiser or White) to use.

You can skip the top section and dive right in at the first starter stage and stick any random value in for the starting cell count if you want to see what the various models have to say about saturation effects...

Cheers!

 

[IslandLizard]

I like using BrewUnited's Yeast Calculator.

100-125 billion cells is for a fresh pack, like manufactured yesterday. Cell count has been going downhill from there on.
WhiteLabs Pure Pitch packs seem to fare quite a bit better, with no less than 80% vitality after 5 months (!) of refrigerated storage.
Either can be brought to 300 billion or more in one single step.

You really should look into a stir plate, easy to build yourself. The constant supply of fresh air (21% O2) helps grow more cells faster, rather than fermenting out the starter wort.

A cold crash is often needed to flocculate all the yeast, so clear starter beer is left on top. That's what you'd decant most of, leaving some behind, to swirl up into a pourable slurry.

Look into yeast ranching too, basically making a somewhat larger starter than needed, so you can save some yeast out to make a starter from next time. And so on.

 

[day_trippr]

fwiw, Imperial cans hold 200 billion cells, roughly double Wyeast and White Labs current retail packaging...

Cheers!

 

[IslandLizard]

However because he doesn't list a value for 200 billion pitched into a 1 L starter

The inoculation rate would be too high for good growth. 25 million cells per ml is nearing the limit.

Again, use one of the yeast calcs linked to before.

 

[pym99]

Thanks for all the great info. I was shocked to see that the Brewer's Friend yeast calculator projected only 28 billion cells from a package dated from just October. That seems recent to me, but I guess it's a long time for yeast!

I've looked at the commercially available stir plates, but given the cost I have prioritized other brewery expenditures, like finally buying a chest freezer and setting up my old upright freezer as a fermentation chamber. I'll have to look into building one.

Thanks again everyone!

 

[IslandLizard]

Thanks for all the great info. I was shocked to see that the Brewer's Friend yeast calculator projected only 28 billion cells from a package dated from just October. That seems recent to me, but I guess it's a long time for yeast!

I've looked at the commercially available stir plates, but given the cost I have prioritized other brewery expenditures, like finally buying a chest freezer and setting up my old upright freezer as a fermentation chamber. I'll have to look into building one.

Thanks again everyone!

Many calculators are quite conservative and built on the same model of yeast viability vs. age. But so much depends on storage conditions and the amount of oxygen entrapped within the slurry and storage container. White Labs' Pure Pitch packs are testimony of better packaging methods to withstand the test of time better. I've successfully rebuild pitchable amounts from yeast that was stored 2 years in the back of my fridge in only 3 steps and 2 weeks. All yeast calcs show (close to) 0 viability.

Do a search for building a stir plate, a computer fan, some form of speed control, a Neodymium magnet (or 2) and a few pieces of hardware you may already have, are all that's required. Plus 1 (or 2) 1" stir beans.