General Category > Yeast and Fermentation

pitching on a yeast cake

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You need to take sanitary precautions, but you are pitching sanitary wort onto yeast. The environment the wort is going into should be sanitary, you just have to make sure you arent introducing anything wild while transferring. If you are doing it pretty quickly and covering the yeast in between transfers you should be good to go.


--- Quote from: mwhammer99 on March 15, 2013, 06:30:29 AM ---Dumb question from a newb here, but if you pour wort on an existing cake, doesn't that mess with your sanitation?

--- End quote ---

I don't see it any different than re-pitching yeast.  Your fermenter should have been sanitized the first time so the real danger is introducing bacteria when you open it to siphon out or add the new wort.  What I will do, and its working for me, is to brew a 5 gal batch of beer and then split that yeast into a new bucket so that I have 1/2 of the yeast as a "re-pitch" and 1/2 directly on the old cake.  I only do this once because I do have sanitation concerns so I don't continually re-use the same cake without a clean out.  I do think that you will have some over-pitching concerns if you use the whole cake for an ale.  And yes, it's gonna take off like a rocket so be ready with a blow off tube if you are using a carboy.  For a lager, I will put the wort on 100% of the old cake because I've been told you can't really over pitch a lager.

The thing with washing yeast is that it is really not "washing", it's rinsing and you won't remove any bacteria.  In fact, if you're not careful you can also introduce bacteria just like anytime you have the yeast open to the air.  I've never done a true acidic wash and I don't think too many people do. 

Sanitation is not much of a concern, assuming the beer you had in there previously was sanitary. Over pitching definitely is. Also dead yeast cells are a concern. Also the braun hefe on the side of the carboy is a concern because it has some bitter and nasty flavor compounds you probably don't want in your beer. Left over hop compounds might be an issue as well.

Unless you are going from a very low gravity beer to a high gravity beer (ordinary bitter to barley wine) I think you are much better off collecting the yeast slurry, using the pitching calc at and approximating an appropriate pitch from there. You are better off pitching "the right" amount of yeast than overpitching, everytime.

Joe Sr.:
Everything Keith says is correct, IMO.  It's so easy to just swirl the carboy and pour the yeast cake into a sanitized container that there's no real reason to repitch into a gunked up carboy.

However, there's no great harm in doing so and it will ferment and make beer.

You're better off taking the extra step.


--- Quote from: davidgzach on March 15, 2013, 04:30:33 AM ---Yep.  Lag timeframe is a different story!  It will take off fast.....

If you do not pull out some yeast, you should pitch a higher gravity beer. 


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I don't want to pitch a higher gravity beer

I frequently do this with my Mild's and Scottish Ales.


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