quick question regarding racking a new brew onto an old yeastcake

when you rack a new beer onto a yeastcake, do you aerate it? or do you just pour the wort onto it, and cap it?

Aeration isnt as important in this case, but I usually aerate for 15 to 20 min anyways. It makes me feel better.

- magno

you are still gonna need aeration. In line would be the easiest way to do it. but I have had good luck racking onto my yeast cake shaking it up to get the yeast into the suspension and then throwing the o2 stone in for a few minutes.

Kind of a trick question. Pitching on a yeast cake will ferment an oxygen depleted wort. Oxygen is needed to increase cell numbers for a compete fermentation but a complete yeast cake contains more than enough yeast cells already to do this. However, the growth stage of yeast makes up part of the overall flavor profile of beer, reason for not pitching with too much yeast.

You really just need to pitch part of the yeast cake and aerate the wort.

I rack on it, then give it a 45 second shot of O2.

I always aerate on the theory that letting the yeast go though a growth phase makes it stronger. Even with aeration, that phase will be very short, only a couple generations.

I'll be racking a new brew onto a yeast cake tomorrow. I'm doing my "5 Count" house IPA on top of a yeast cake from an Alpha King clone. My aeration choices are shake the bucket up or stir it for a few minutes. What are the differences? Pros/cons. How hard/long should I shake it? The beer I mean...

a few more hours and its a weekend of seeing a Flaming Lips concert, brewing and football. Damn I love the fall.

I think I read somewhere that aeration of the yeast itself is bad as it breaks down the cell walls. I'll aerate the wort in the kettle then toss that on top of the yeast cake. PT Ray is right though. You don't need the whole yeast cake.

Pitching Rate calculator from Jamil Z.
http://www.mrmalty.com/calc/calc.html

I also agree that you do not need the whole yeast cake. Just scoop out the best stuff and use that for the next beer. The yeast pitching rate calculator is an awesome tool.

screwing around with the calculator...i never used the options for aeration before. i never realized how much of a difference intermittent shaking has...i've been making my starters too big!