Racking onto old yeast cake

[A2HB]

Is that a thing people do? Instead of washing and trying to clean the yeast can I just put the new beer on top of the old yeast cake that's still in the fermenter? There is obviously trub and stuff mixed from the previous batch but they are similar styles so not worried about flavors leaching or something like that. I'm somewhat lazy and I don't want to go to the trouble of washing. Thanks for any advice

 

[botigol]

I've done it, but not regularly, and I have read that others do it as well. The only issue I see is that you are overpitching the yeast, so there could be some flavor and/or aroma loss.

 

[Yooper]

Sure, you could do that. But it all but a very few cases, it would be extreme overpitching.

Why not just use 1/3 or 1/4 of the yeast cake, scooping out the rest or pouring the rest into a sanitized mason jar to use next time? It's definitely not hard to do, and then you've got enough yeast for four or five more batches already to go.

That's what I do. After the fermenter is emptied of beer, I pick up the fermenter, swirl it around, and pour the yeast cake into 3 or 4 mason jars. Then, each quart sized jar is more than enough for my next 10 gallon sized batch. That way, I get about 5 batches of 10 gallons of beer with just that yeast from one 5 gallon batch.

There is no reason to "wash" the yeast. Just save it in a jar in the fridge.

Here's some food for thought: https://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/

 

[Jadub]

Case in point, i did that for my last 5gal IPA. I was feeling lazy, in a hurry, so i put the wort on top of a gumballhead yeast cake. Too early to tell if it affected the flavor, but man, the airlock was churning just 2 hours later. Overnight, it gurgled sludge all over the room. It continued chugging sludge out of the airlock for another 24hrs.
Go with what Yooper said. Good option.

 

[A2HB]

Awesome thanks for the replies. Yooper, that's exactly what I wanted to do, just scoop some out and save the rest. I'll sanitize the jars, pour out cake into the jars and use about 1/2 cup of the cake for the next batch. I figured it was an option but I never see anyone talking about it so thought I would ask. How long will the jars keep in the fridge like that? Do you know if they would freeze and still work?

 

[Yooper]

Awesome thanks for the replies. Yooper, that's exactly what I wanted to do, just scoop some out and save the rest. I'll sanitize the jars, pour out cake into the jars and use about 1/2 cup of the cake for the next batch. I figured it was an option but I never see anyone talking about it so thought I would ask. How long will the jars keep in the fridge like that? Do you know if they would freeze and still work?

I use mrmalty.com's yeast pitching calculator. It has an option for slurry, and it works pretty well. That is really helpful in deciding how much yeast to use.

It can NOT freeze, but stored in the fridge the yeast lasts a long time. After a month or two, it's a good idea to make a starter to "wake up" the yeast, but I've used yeast that is 7-8 months old that way.

 

[BrotherBock]

There is no reason to "wash" the yeast. Just save it in a jar in the fridge.https://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/

Can you elaborate? Why would I not want to worry about the dead yeast and trub that comes with it?

 

[fizgig]

Yeast drop the pH and create alcohol to make it hostile for other organisms, by removing the beer and adding water, you are undoing that and it could make it easier for bacteria to multiply.

 

[WoodlandBrew]

The number of cells can be approximated by measuring the settled slurry. If you are brewing all grain and pouring everything from the boil kettle into the fermentor you'll have 1-2 billion viable cells per ml. If you whirlpool or are brewing extract with specially grain 3 billion per ml is common. If you brew all extract expect 4 billion per ml.