Reuse yeast cake?

[AZBeer]

I have an IPA in primary now, and I have a different IPA as my next brew. I want to bottle on a Saturday, then brew the next batch on a Sunday.

Can I just throw the fermentor in the fridge with the yeast cake, and reuse it the next day?

 

[RedlegEd]

I have an IPA in primary now, and I have a different IPA as my next brew. I want to bottle on a Saturday, then brew the next batch on a Sunday.

Can I just throw the fermentor in the fridge with the yeast cake, and reuse it the next day?

Hi. The short answer is yes, you can. A better practice would be to leave a little beer in the fermenter, swirl to thoroughly mix the slurry, pour it off into a sanitized container (qt sized mason jar or growler are good.) If you're going to use the same fermenter, clean it thoroughly and sanitize before racking new wort into it, then use a calculator to determine how much slurry to pitch. Don't waste your time "washing" it. Hope this helps. Ed

BTW: Go Cats! I'm class of '78

 

[triethylborane]

I would dump the yeast slurry into a sanitized mason jar. Here is a calc to figure out how much yeast slurry to pitch:

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

This way you can get the fermentor cleaned and sanitized. Im concerned that acetoobacter would take hold with the O2, but hey, if you are up for an experiment to see what happens.

 

[AZBeer]

Makes sense, thanks guys.

Hey Ed
Class of '07, Bear Down.

 

[bstacy1974]

I just did this two days ago, but closer to an hour after emptying the fermenter. While the mash was going, I transferred a blonde ale into a keg, then sprayed the underside of the lid and inside my bucket fermenter with Star San. Snapped the lid back on and proceeded to finish my brew day. Just over hour later, I drained my freshly cooled IPA wort into the previously emptied fermenter.

If time allows, may you could bottle Sunday morning then brew after finishing, but I'm sure you've already thought of that scenario.

For some reason, I've seen this topic pop up over the past week or so on several different message boards. Some people swear by the yeast washing and repitching idea (which I've recently started to practice), but others seem to think the idea of over pitching is a myth. Under pitching seems universally agreed upon as bad, but over pitching is a split concept, some good, some bad. Thought I'd experiment to see how it works out.

One observation right away was the speed at which fermentation began. The yeast is Mangrove Jack's M44 West Coast ale strain, which is a notoriously slow starting yeast. Typical lag times I've observed with this product are 3 to 4 days before you really notice the air lock going. (Which is not the only sign of active fermentation, i know, but we all use it a simple gauge for activity.) Pitching on the yeast cake, I had active bubbling in less than 4 hours. Good luck and boil some mason jars, just in case.

 

[eastoak]

but others seem to think the idea of over pitching is a myth.

pitching the proper quantity of yeast for a given gravity is not a myth but it also is not the end of the world within reason. there is such a thing as an overpitch that will result in a thin, weird tasting beer; a 1.050 OG wort on a whole yeast cake, for example, may not work out as well as 1/4 of the same cake or less. by the same token a tablespoon of yeast will eventually ferment the same beer but it will take longer, may have off flavors and may not finish out.

https://wyeastlab.com/pitch-rates

 

[Calder]

A beer will produce roughly 6X the amount of yeast required for the ideal pitch of a similar brew (abv and volume).

Therefore pitching on a cake is over-pitching. When you over pitch, the yeast does not fully reproduce and you use 'old' yeast to finish the ferment. It does affect flavor, it does affect FG. But you may not notice it. If you continue the practice for several batches, you will eventually notice an issue.

Obviously some yeast will die while you are messing about with the brews. I generally work off using a quarter of a fresh cake = correct pitch level for a brew of same OG.

If using slurry within a week, I would not even think about washing, and would straight pitch.

 

[tjosborne]

I was thinking about this just tonight. My plan was to brew a 4-4.5% patersbier and then rack a 9-10% Trippel or quad on top of that cake. Basically my patersbier would be a starter, right?

 

[davemattb]

+1 to the slurry in jar. Pitched onto yeast cakes on 2 batches and wasn't pleased with results.