Possibly dumb question: Reusing yeast

[Random Badger]

Lots of people evidently reuse ale yeast successfully from one brew to another. Just wondering whether there may be any potential "issues" in doing so for different types of beer? For example brewing a stout then pitching the yeast cake into a pale ale, or brewing a best bitter and then reusing that yeast for a NEIPA? Or making a beer including fermentable sugars and then pitching that yeast into an all malt brew?

 

[Scottyburto]

Some strong flavours will carry over and affect your next brew. It's a complicated question with no single easy answer.

Ultimately all things being well (healthy yeast/temp/sanitation/etc) you can just put a new brew on top of a previously fermented trub/yeast cake. But it's a random situation that you can't know the end result.
For example it works quite well with turbo cider where you're making the same thing again.

From a more complicated route you can "harvest" yeast from a finished brew, store it correctly and reuse it at a later date with minimal flavour carry over.

If you search the forum it's been discussed at length a few times even quite recently.

 

[Scottyburto]

https://www.thehomebrewforum.co.uk/threads/quick-starter-or-pitch-on-old-yeast-cake.93345/

 

[Jim Brewster]

Darker/stronger after a lighter beer is fine, but the opposite order there's a potential risk you could compromise the beer.
Pale ale then stout yes (I have done that)
Bitter then NEIPA should be OK
But the reverse is possibly a bit of a gamble, I'm not sure

 

[NotSure]

An easy one to start with is a Pale Ale followed by an IPA with similar hops. You could just as easily do a Porter or Stout after the Pale. Just keep the OG of the Pale relatively low. The main issue as I see it would be overpitching. Anything that's intended to have a strong yeast character should not be the second beer.

 

[Random Badger]

The beer in my fermenter now should be very dark (Export Stout with added black treacle) so maybe I will stick to pitching fresh yeast for the IPA I am intending to do next.

 

[cushyno]

Don't do a hoppy ale with a stack of dry hops and hope that using the yeast cake will be fine in the next delicately hopped brew. Been there, done that. Citra destroys the flavour of ekg in an English bitter.

If the first beer is a big one, i.e. gravity over 1.050, think twice about pitching the slurry into anything else. If your original pitch was of decent size, plenty of cells, the yeast may not be stressed too much. If pitching a standard 0.75bn cells into a big beer they may be a bit stressed afterwards and may throw off unwanted flavours in the second beer.

If course, different strains cope with stress to different degrees. Your mileage may vary.

 

[Darren Jeory]

I have a question on this...how long will it keep for and also I associate trub with off flavours...am I talking boll*cos?

 

[Darren Jeory]

Haha...should have been boll**ks but I think you know what I meant

 

[Darren Jeory]

Also (sorry) is there a correct method for harvesting and pitching or do ya just throw a jar full of trub in the next brew?

Thinking of doing another kolsch...I have thrown 3 packs of yeast in this one so am thinking there must be some reuse in it.

 

[NotSure]

Also (sorry) is there a correct method for harvesting and pitching or do ya just throw a jar full of trub in the next brew?

Thinking of doing another kolsch...I have thrown 3 packs of yeast in this one so am thinking there must be some reuse in it.

Yes, there is a correct method, but pitching on top of old yeast cake isn't it. Among the reasons people don't use the correct method would be (1) it's a bit of a pain, and (2) the more handling of the yeast could me more opportunity for it to get infected.

When I pitch directly on yeast cake I'll time beer #2 to be brewed shortly after beer #1 has been bottled/kegged. If it's a day or two and an ale yeast, I'll let the fermenter sit at room temperature. If it's longer, I'll either pop the fermenter in the fridge or put the slurry in a container in the fridge. I've had no issue with off flavours, but I also intentionally make beer #2 a more flavourful beer than beer #1.

I haven't tried it with a kolsch yet, but I'd like to in the future since I've found kolsch yeast to be fickle and if the first batch worked, then it stands to figure the second one would as well.