What method do you use to rehydrate a yeast cake and prepare it for pitching?
I’ll be transferring a 6% lager from primary to the secondary this weekend, and wanted to use the yeast cake right away in another lager. What method would you suggest to get that yeast healthy for next pitch?
Wouldn’t think you’d need to do anything. Just rack the new batch into the fermenter right on top of the cake.
If you were using an ale yeast, I’d suggest using only part of the slurry. But since you’re doing a lager, I’d go with the advice above.
How long has it been sitting, and what is the gravity of the new batch?
Yeast cakes should be used within a week or two otherwise I would suggest making a starter from it. Go to mrmalty.com and estimate the quantity of slurry required and pitch on that ideally within a day or two.
So from what you guys are saying, the yeast cake is ready to go to work again with out any nutrients or any type of help?
The lager has been in primary fermentation for 25 days @ 48F, with an included D-rest for 3 days @ 65F… The new humulus lager hoppy lager batch will have an expected O.G. of 1.060.
I think it will be fine, there should be plenty of viable yeast there to finish the new batch if you just rack on top of the cake like hokerer/Denny were saying. I use nutrients in all of my batches, but other than that I don’t think you need to do anything special for this yeast cake.
+1 to all, only to say that if you want to use a clean container, just swirl it (after racking your beer of course) and pour it into the new one.
You could pour it into a sanitized jar and let it settle. That’ll give you time to clean the fermenter and let you use the MrMalty site to actually measure the amount to use.
That said, when I brew back to back batches I often syphon the finished batch out of the primary and then fill it with the new wort right onto the yeast.
Thanks all, for the suggestions.
I will pitch the yeast cake as is.
Probably a stupid question, but is it preferable to use the yeast cake from the primary or the secondary (assuming a secondary is used of course)? I would think the yeast population would be higher from the primary, but in the secondary I would think the yeast sediment would be “cleaner” (i.e. less unwanted trub).
OTOH, if you use the secondary, you’re selecting the less flocculant yeast. All if which is a way of saying it doesn’t really matter all that much.
Update: Less than one hour after pouring the new wort right on top of the lager yeast cake, the violent fermentation created enough force to pop the blow off tube right off the carboy. I’ve never seen that before, especially since it’s fermenting at a constant 43F. Only 3 full days since the inoculation and it seems to be almost done.
Sounds like your making beer. 
Congrats. Hope it turns out well for you. 
What’s the rationale for only using part of the yeast cake for an ale? I know lager need larger starters but what’s the downside to using a large starter for an ale?
The growth phase of the yeast produces esters which add to the characteristic ale flavor. Overpitching will reduce those.
Or, as I often point out, according to Dr. Clayton Cone of Danstar/Lallemand, yeast growth will reduce esters. That’s been my experience with slurries.
Thanks for the link Denny.
My take on it . . . this is an important sentence. “Ester and other flavor component production or synthesis is a complex subject because there are so many variables taking place at the same time” ;) It’s very complex, and because of that I am not convinced that the effects he mentions can be entirely put into growth+/growth- bins.
I think this is important too: “I am also sure that there are beer makers that have experienced the very opposite with each of the variables.” Several of the conditions that he says “inhibits or slows down yeast growth” I call “stressing your yeast”, for example “low nutrient, low O2”, and we both agree that it will increase ester production.
There is plenty of evidence that ester formation increases with temperature, but I don’t know that those studies differentiated between high start vs high finish temperatures so I’m not going to comment on that.
I think the problem I’m having with his statement is that we know that ester production comes after glycolysis, but we also know that glycolysis is an important part of amino acid synthesis, for example valine and leucine. Those are required for all protein synthesis. You can supply them to the yeast, which explains why nutrients reduce ester formation. So inhibiting amino acid production reduces ester formation, however, that doesn’t mean that growth is inhibiting ester formation. One could just as easily argue the other side of the coin: since growth requires proteins, and protein synthesis requires amino acids, and amino acid synthesis produces esters, growth produces esters.
I think the reality is that “growth” is too macro of a level to discuss ester formation.
I refer you back to his first sentence: “Ester and other flavor component production or synthesis is a complex subject because there are so many variables taking place at the same time” ;D
Tom, I really appreciate your take on this. And I agree that the first sentence is kind of a CYA statement! But to me, it shows that it isn’t as cut and dried and some people would have you believe. The fact that my own experience pitching less slurry led to cleaner beers shows that.
As always Denny, trust your empirical results over experiments done under conditions that are not the same as your beer making.
Because of the complexities, I think you’re right, it is not as cut and dried as some people say (including me sometimes ).