Re-pitching on to yeast cake for first time

[rochs918]

Hello all, first time poster, all-grain brewer for about 1 year now. I am making back-to-back 5 gallon batches of an identical beer, and I'm hoping that they come out identical tasting as well. I am thinking about brewing batch #2 and racking batch #1 on the same day, so I was considering re-pitching directly on to the yeast cake. I've done some research on this forum about this, but I'm still a little unsure as I don't want to screw something up and waste a whole brew day. My main questions are, do you dump/drain the boiled, chilled wort directly on to the entire yeast cake, with splashing and all for aeration? Or do you also shake/aerate the fermenter once it's all sealed up? Any advice would be appreciated. Prost!

 

[Coolmac]

If you dump straight onto the yeast cake they are unlikely to come out tasting identical since the quantity of yeast pitched does affect the flavour. Rather wash the yeast and put the correct amount back into the 2nd batch.

That said, I have dumped straight onto the yeast cake before and the act of pouring put more than enough oxygen in, considering the amount of yeast already there. The fermentation will be explosive...

 

[stevo155]

What is the beer you are making? If it is something you dry hopped, you should rinse the yeast. Otherwise, dump away but as Coolmac said, be ready for an explosion ( a blowoff tube may be in order ).

 

[onthekeg]

When I am reusing cakes, I generally only use half the cake left from the previous batch. You can add some preboiled and cooled water to the cake, swirl it up and dump half down the drain.

 

[Boodlemania]

I have pitched directly in the past with "success", but I have changed my methods on repeat beers to rinsing the yeast and putting about 1/3-1/2 of the cake back into a clean fermenter.

Essentially, I put just enough water in the fermenter to suspend the yeast and trub, then pour that out into a clean container. When ready to pitch, I resuspend the yeast and put 1/3-1/2 of the volume into the new fermenter. I do not wash in these instances as I do not reuse yeast if it's been stressed or I feel the original batch had alot of trub.

If I'm going to save the yeast, I'll follow the "Yeast Washing" directions found on this site.

 

[SickTransitMundus]

Pitching directly onto yeast cakes is a bad habit. I used to do it all the time, but I stopped. As others note, you'll be overpitching your second batches - this can cause a variety of off-flavors. I had too many subtly "off" batches, and eventually pinpointed overpitching as the culprit. At a minimum, wash the yeast and use the calculator at mrmalty.com to estimate the amount to repitch.

Personally, I use starters from fresh smack packs on each of my batches, but that's just my preference. Washed yeast should be acceptable for most repitches. I imagine that aeration of the new batch isn't necessary because the yeast already have strong cell walls from the first ferment.

 

[beergolf]

I usually bottle while I am brewing and have reused yeast a few times.

I ferment in buckets so I just sanitized a container, scooped about a cup of yeast out of the bucket. Clean and sanitize the bucket and put in the new wort and pitch the saved yeast. Works fine.

 

[HomebrewMTB]

You've basically done a 5 gallon high-gravity starter so that is way too much yeast for one batch. You probably only need 1/4 of that yeast cake at most for your next batch. If your donor batch is a big beer or you under pitched, the yeast may be stressed and it might be better to make a starter with the slurry rather than a direct pitch. Again, it's better to wash the yeast and not pitch directly on the old yeast cake. You can do whatever you want but it's not ideal pitching on yeast cake. It might make an interesting experiment for you though.

 

[gtwarren1966]

Why do you want to repitch onto the yeast cake instead of drawing out the proper amount of slurry from the yeast cake and pitching the proper amount of yeast? What benefits do you hope to gain other than avoiding a little bit of extra work?

 

[RRussellTx]

I re-pitched on my yeast cake for the first time over the weekend and I was surprised how fast and strong the fermentation kicked in. After 8 hours I could have hooked a hose up to my airlock and blown leaves off my driveway!! I'll be cutting the yeast back on future batches for safety purposes alone!