Harvested Yeast Cake

[Sbe2]

Normally I overbuild starters to harvest yeast. But when I wanted to brew, I didn’t follow the 7 “P’s” and therefore I didn’t have enough DME to make a starter.

Fast forward two weeks, I had about 12 oz of beer after kegging. I swirled the trub and all, and poured it in to 2 - quart size mason jars.

Should I leave it in jars and just use the trub and all in my next beer? Use a jar to make a starter? Or wash the yeast?

 

[LLBeanJ]

Use the trub. No need for a starter and definitely no need to wash.

 

[Sbe2]

Will it be ok to leave it for a few weeks in the fridge like I normally would?

Use the trub. No need for a starter and definitely no need to wash.

 

[LLBeanJ]

Yes, a few weeks is fine.

 

[RM-MN]

Will it be ok to leave it for a few weeks in the fridge like I normally would?

Yes, a few months will be fine. You will lose a bit of viability but with half the yeast cake (if I read that right) you have twice as much yeast as needed so if the viability goes down to half you have just the right amount.

 

[Sbe2]

Yes, a few months will be fine. You will lose a bit of viability but with half the yeast cake (if I read that right) you have twice as much yeast as needed so if the viability goes down to half you have just the right amount.

Yup, I have the entire yeast cake in two mason jars.

Would you recommend making a starter with one jar or just pitch it in to my next batch?

 

[RM-MN]

Yup, I have the entire yeast cake in two mason jars.

Would you recommend making a starter with one jar or just pitch it in to my next batch?

The general thought is that you only need about 1/4 of the the yeast cake for the next batch. Making a starter with it will increase the number of yeast cells so you'll be pitching quite a bit more than needed unless your yeast was stored incorrectly or for so long that you have lost a lot of viability. With all that in mind, Brulosophy did an experiment where he made 3 batches of beer and pitched different pitch rates, then had several people sample to see if they could reliably pick out the one that was the right pitch. One was pitched with 7 times the recommended amount, and another was pitched 1/5 the recommended with the third the recommended amount. That should have been an easy set up to choose the one with the right pitch but the samplers couldn't conclusively choose that one.

With a massive overpitch you can expect the beer to ferment with almost no lag time and probably to a lower FG but I don't think that 2X is a massive amount in this context. I'd just pitch one jar and see what happens. If you don't have a lot of headspace in your fermenter and/or good temperature control you will want to have a blowoff tube immediately in case it goes explosive. I understand that washing the ceiling and walls after a blowout isn't the most fun part of brewing.

 

[Sbe2]

@RM-MN thanks for the reply. I ferment 6 gallons in my 7 gallon fermonster so I am good with headspace. With my setup I always use a blowoff tube.

FWIW: