Starter Repitching from Slurry Question

[yournotpeter]

I have posed this question before and don't think I asked it correctly.

I'm going to use some washed German Hefe (WLP 300) in a batch. The MrMalty pitching rate calculator says I need 136 milliliters of slurry (based upon harvest date, OG, etc...). I easily have 136 milliliters of washed yeast but still want to make a starter to wake those refrigerated yeast up.

How big of a starter do you think I should make? I don't want to grow more yeast, just wake up the ones I have.

 

[a10t2]

A liter should be plenty. I'd start it ~8 hours before you brew. Hopefully that will put the yeast into the main wort at high krausen.

How old is this slurry? 136 mL seems like a lot.

 

[yournotpeter]

A liter should be plenty. I'd start it ~8 hours before you brew. Hopefully that will put the yeast into the main wort at high krausen.

How old is this slurry? 136 mL seems like a lot.

I harvested it on June 13 of this year.

Unless I'm using the calculator wrong....it's based upon a 1.050 OG, harvest date of 6/13, and the defaults for yeast concentration and non-yeast percentage.

 

[a10t2]

No, I'm sure you're using it right - it just makes some assumptions that don't match up with what I've seen. For slurry that's been stored in the fridge for more than a few days, bump the density up to 4+ billion/mL. (I found 4.3 based on a density measurement, YMMV). I think 2.4 (the default) is for slurry that's coming directly out of a fermenter and has been stirred up, not packed yeast. I also like to calculate viability based on the pitching date rather than the harvest date. Most of the viability loss will be in the time the yeast cake is in the fermenter prior to being harvested.

Anyway, I end up calculating about 90 mL. You're in the ballpark, but for a hefeweizen I'd prefer to under-pitch if anything.

 

[yournotpeter]

I think 2.4 (the default) is for slurry that's coming directly out of a fermenter and has been stirred up, not packed yeast.

Interesting - and after contemplating this, I think you're absolutely right. That certainly changes the totals!

So, with the assumption of using 90 mL of slurry, you'd still suggest the 1 L starter to get those yeast woken up?

 

[TotemWolf]

I'm not saying that this is the way to do it but here's what I do. I brew every weekend and for the most part only use two types of yeast.
I harvest the yeast from the primary about a week after pitching that way I get the flocculent yeast that I want. I chill the yeast in the fridge until needed. This also packs the yeast thickly together.
Two days before brewing I make a 1 L starter. I let the yeast set and warm a little before I pitch the amount of yeast called for by Mr Malty. I use the settings of 3.2 billion cells/ml and 15%.
After a day, when the starter has done it's thing I chill it to drop the yeast. I then pour off most of the 'beer' and pitch the yeast.

I always get fast starting good fermentations. The yeast is not sluggish and flocculates like it should. Great beer every time.

Edit to say.... I haverst from the primary so I use the harvest date for viability

 

[yournotpeter]

Two days before brewing I make a 1 L starter.

Do you use a stir plate? Shake? I have a stir plate, but I'm brewing two batches and one batch is using new yeast from a vial that I need to grow...so that yeast is getting the stir plate. Looks like I'm just going to have to use the shake method for the washed yeast starter. Any advice on that end?