Use yeast a second time

[run4thebrew]

People talk about saving yeast from a carboy and re-pitching it in new wort. Is it OK to just leave it in the bottom of the primary and just throw new wort on top of it? If so should I do it immediately, or can I do it in the next day or two? Is this a totally crazy idea? Thanks for all of your wisdom.

 

[pannell77]

Yes you can pitch right on top of the yeast cake. I would do it right away to avoid possible infection, I have never tried waiting a couple days. i am sure someone else will chime in with some more wisdom though.

 

[run4thebrew]

Not to sound lazy, but how many times can I do that? Can I harvest the yeast after that second pitching and throw it in a jar and refrig for use at a later date.

 

[pannell77]

yep, no problem with doing that at all. There are some great writeups on here about yeast washing. I have some yeast that I have re-used on 4 batches so far.

 

[masskrug]

Is it OK to just leave it in the bottom of the primary and just throw new wort on top of it?

You can, but it is a serious over-pitch. You only need about 100ml of clean yeast. I use one jar to scoop out about 3 cups of yeast. My jars are sanitized with Starsan beforehand. I let that settle out and pour just the creamy white top part (along with some beer) into another jar. Pop that into the fridge until brew day. Let it warm up to room temperature for about an hour before you pitch.

http://www.mrmalty.com/calc/calc.html

Click on "Repitching from Slurry"

Good luck!

 

[Toga]

MassKrug hit it on the head. You are way over pitching if pitching right onto a cake. I recommend taking a stab at yeast washing. You can easily harvest enough pitch-able yeast for your next batch and have enough for to do make starters from for a couple batches or more. If you are going to brew in just a couple days you can also just sanitize a ladle and scoop a cup or so of the cake into a sanitized jar or even a zipper bag. The mr malty calculator will tell you approximately how much slurry you will need. I many cases it over estimates and does not give the yeast much credit when it comes to viability when storing washed or rather rinsed yeast.

Here is a link to an easy washing method that seems to work well for many including myself. https://www.homebrewtalk.com/f163/yeast-washing-illustrated-41768/

 

[run4thebrew]

Thanks a lot! Love this forum as much as I love my new hobby!

 

[KeystoneHomebrew]

For the homebrewer not trying to over complicate, repitch on the cake only once, ideally with a second beer that is higher gravity. Have your 2nd batch wort cooled, then transfer off the cake into wherever its gotta go, then add the wort right onto the cake.

Eventually the yeast is going to mutate, but you'll have other problems like all the hop matter and whatever else got in there pose a problem before that happens.