I’m gonna be kegging a lager next week after doing a D rest and I’m wondering how much of the slurry you’d recommend for the next batch? I am planning on splitting the slurry from a 5 gal batch of 1.060 wort into two batches if possible. Given the amount of slurry that is left after 5 gals, I’m assuming that there is more yeast in 1/2 of the slurry than in a starter but I thought it best to check. The other option would be to split the slurry and make 2 starters but I don’t really imagine this is necessary.
So, would 1/2 the slurry from a 5 gal batch be enough for the next 5 gal batch? I checked Mr. Malty and with a medium range thickness and the highest possible non-yeast percentage, it says I need about a cup so I think I should have lots. Just never sure with that program how accurate my assumptions are about thickness and non-yeast percentage.
Thanks
The most accurate way to determine the proper consistency is to count the cells on a hemocytometer under a microscope. However I look at the consistency of the slurry. If the slurry is like a thick gravy, I would consider that to be approaching a thick slurry. It also depends on the yeast, WLP002 is a very viscous yeast whereas WLP 830 is fairly thin. You’ll have to make a judgement call on it.
Another consideration is the yeast cleanliness. Are you going to rinse the yeast? I assume not…right? If not you’ll have to account for the trub and hop carryover from the BK as well.
FWIW - I use half a cake for the same size batch of reasonably similar gravity lagers. That leaves half for another batch or if too much time passes, I will make a starter with some of it.
300ml of the slurry is all you’ll need - that’s just a bit more than a cup. I routinely brew two lagers in a row - ferment the first one for about 10-14 days, and then, two weeks after the first brew day, brew and re-pitch slurry into the next lager.
What size batches are you doing? If it’s clean and fresh yeast that’s over a trillion cells, which for a 5-6 gal batch at average gravity is around 4 million/mL-°P, about three times the standard lager pitching rate.
I guess I need to better understand what you are calling slurry. I am referring to the sediment on the bottom of the carboy as it sits today. Not washed yeast which has had most of the trub removed. I’m picturing siphoning off the beer, dumping the carboy into cleaned and sterilized bowl and dividing this equally between two new 5 gal batches.
If the new beers are roughly average gravity, that would be pretty significant over-pitching - not that that’s the worst thing to do to a lager. I’ve never had a slurry come out of a fermenter that was less than ~3.5 billion cells/mL. So even if your viability is low and the non-yeast percentage high, 200 mL is about the maximum you’d need for an average-gravity lager.
Lagers are hard to overpitch at the homebrew level IMHO. I use half a yeast cake more or less. But I am usually using the yeast from a primary that has gone a full month at pretty cool temperatures (<50F for lagers usually). No science there, I admit, but I prefer a slight overpitch on lagers to an underpitch.
