Reusing yeast from primary

[manicmethod]

Today I was racking a beer to secondary and brewing a similar beer so I decided to wait to rack til I was ready to put the new wort in the fermenter and just put the new wort straight into the primary I just freed up. I also ran out of airlocks (apfelwein and mead hog up the carboys and airlocks) so I grabbed some hose and made a blowoff.

Not cleaning/sanitizing the fermenter was making me a little anxious so I hopped on and google'd it and it turns out I was doing something completely normal (and the fact that I had to use a blowoff was a good thing) so now I'm feeling good, 3 hours later and there are constant bubbles from the blowoff (nice!).

My first thought is "Why the hell haven't I been doing this all along? I don't know how many weekends I made a starter, racked, cleaned, sanitized, brewed and used the same yeast. I wish someone had told me to do this when possible a year ago"

My second is a question. How many times can you do this? I know you should brew the same or bigger/darker/hoppier but if I stick with the same basic recipe can I do this indefinitely? Is there a point where I should really ditch the yeast and clean the fermenter? Do many other people do this? If so, why not?

 

[ACbrewer]

First answer -I've got no idea.

Second answer - at least once, I've read up to 10 to 12 times. Over time, the yeast get stressed and won't produce a good brew this way. So somewhere between 1 and 10. There are factors that reduce the reuse times relate to the stress put on the yeast by the ferment - ie is it pushing their range by not having enough O2, high gravity, odd ferment tems. If you are doing the same receipe and it is an ok one, keep going. I read one guy who did this an at 7th generation, it fermented to FG in 24 hours from pitch.

I did this once sorta - made skeeter pee according to receipe which does this. I don't do this because every beer I brew is different from the one before. I don't think I've yet to brew the same beer that I did in the past.

 

[manicmethod]

I don't brew the exact beer but I pretty much* brew exclusively IPA's so the differences are minor. I just started AG (This is my 4th batch) and I'm trying to get mashing down pat so aside from hop changes they've been close.

* My first AG experience yielded a stout when I was going for an IBA...

 

[reezle]

You can wash the yeast to clear some of the flavors. Personally I tend to grab a quart of the trub after racking to primary (a few days before brew day) then sanitizing the primary.
On brew day I take the trub that has settled in it's jar and pour off 2/3 of the beer from the top and pitch the remainder.
This way I've got about the same amount of yeast as a starter would have given me and I've removed the bulk of the last beer's flavors (and refuse).
I pitched straight onto the trub a few times but had some issue I attributed to overpitching (too much yeast is as bad as too little).

 

[manicmethod]

What are the problems with overpitching? I know that commercial breweries pitch enough that the yeast don't have to go through a reproductive cycle. I can't imaging the yeast left over in the trub is more than that.

 

[reezle]

The last time I pitched directly onto the cake I was making the exact same beer so I thought it would be pretty safe. The two beers were brewed as identically as I could make them, but the second batch didn't come out nearly as good as the first. It's missing a lot of background flavors and has more of a grain alcohol taste to it. I know it could be any number of hidden variables, but when after weeks (now months) of aging it still hasn't come close to the glory of batch #1, I started looking at the only difference in the batch I know of (the amount of yeast). I started reading up on the yeast life cycles, and ran across this article. Sounds like there is a lot going on before active fermentation that gets missed if you just dump onto your old trub. If there's no lag or growth phases, what uses up the oxygen and drops the pH?

Other nice thing about extracting a reasonable amount of trub and sanitizing the primary is that you can take several jars of it and have some in the wings. (Some of the Scotch Ales I've made ask for a second hit of yeast a few weeks into the process).

 

[DannPM]

You'll want to separate the yeast from the dead cells and trub before using the cake for a second beer.

As a general rule, get a new batch after every eight brews with repitched yeast.

 

[manicmethod]

Hrm. Well I've tried saving yeast before and it worked fine but for me the main reason to do this would be to save time. I don't care about buying new yeast every time but if I could eliminate a clean/sanitize cycle I'm all for it.

I see the point about removing the dead yeast, excess protein, etc in the trub. I still don't understand the overpitching thing. The commercial brewer I talk to says they pitch enough yeast to get the lag down to an hour which implies there is no reproductive cycle for the yeast (what gets rid of oxygen and lowers the pH, I don't know).

 

[manicmethod]

And I'm not sure how reputable these are but these are the several links I visited after I did this:

http://www.craftkb.com/Uwe/Forum.aspx/brewing/10601/racking-onto-yeast-cake

http://www.realbeer.com/discussions/showthread.php?t=8445

http://www.tastybrew.com/forum/thread/213518

And I just found one here:

https://www.homebrewtalk.com/f39/racking-onto-yeast-cake-19510/

Seems like there is some disagreement.

 

[dcp27]

Bob gives a pretty solid argument against pitching onto the cake: https://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/

 

[ACbrewer]

If you beer was ok and you poured new wort on top of it, then there is little reason why that would be a problem. Yes some dust with bacteria could drift in. But it should be limited.

In his yeast book Chris white pretty much said that you could not over oxygenate the wort unless you were using a o2 feed and stone. Also I've read but forget where that trunk provides yeast nutrients. So much so that it helps growth when there isn't enough o2. (Maybe one of Charlie papazan's books )

The best answer I read off hbtalk on over pitch is no 'off' flavors. So a Belgian wit or German heff with the clove and banana esters will be harmed by over pitching. That sort of thing. I'd guess an ipa or apa or something would be hard to over pitch

 

[manicmethod]

Bob gives a pretty solid argument against pitching onto the cake: https://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/

He certainly makes a *strong* point, but not a solid one. Starting a post by "categorically refusing to argue" is enough to raise my hackles. I started looking through some of his sources (non-attributed, non-specific) and don't really see evidence for what he is claiming. His experiential data is probably as good as anyone else's though.

Several others in the responses point out conflicting data, one of the most compelling being the second post.

 

[dcp27]

forgive me for using the wrong descriptor . wyeast makes basically the same points as Bob : http://www.wyeastlab.com/hb_pitchrates.cfm

over-pitching is fine if you want, but I wouldnt aerate if you do, otherwise it will lack ester production (unless that was the point)

 

[DannPM]

Jamil talks about, I forgot the episode, that you can over pitch and even a lager which has almost no esters won't even taste like beer if you pitch too much yeast because yeast growth creates compounds that make beer taste like well...beer. You think your wort tastes like beer after you remove some sugars and add co2 and alcohol and filter out the yeast? There are other compounds other than the usual esters and phenolics you think of that make beer, beer, that are created during the rapid growth phase in fermentation.