Re-using Yeast Cake...Recs & Opinions

There shouldn't be any issue reusing the yeast. I would rack the beer off as normal, then follow standard yeast rinsing procedures to separate the hops and trub from the yeast.

http://www.homebrewtalk.com/showthread.php?t=41768
http://homebrewacademy.com/yeast-washing/

 

This is what the book Yeast says about reusing the whole cake-

A number of homebrewers have adopted the practice of transferring the beer from a fermentor at the end of fermentation and then adding a new batch of wort on top of the yeast cake. This is a bad practice. Can this practice make good beer? Absolutely. Will it make the best beer possible? Absolutely not.

The yeast at the end of fermentation is not just healthy yeast. There are plenty of dead cells present, as well as all the break material and hop bits from the previous wort. You must collect the yeast, look at the population, remove dead cells and nonyeast material by rinsing, and then reuse only the proper quantity of cells in the next batch.

Do not be lazy. Always clean and sanitize your fermentor between batches, and always ensure you are pitching the correct number of cells for the beer you are brewing. Yeast growth is important to beer flavor, and over-pitching (especially with excessive trub) can have a negative effect.

White, Chris; Zainasheff, Jamil (2010-02-01). Yeast: The Practical Guide to Beer Fermentation (Brewing Elements) Brewers Publications.


I prefer to make a larger than normal starter and reserve some of the starter for the next batch. No hops and a lower ABV equals a higher viability. Then do another starter before pitching the reserve.

 

Either the Brewer from Oregon (@jbakajust1 ) or I are misunderstanding the tactical situation. Are you saying the beer has been racked from the primary and the yeast cake has been sitting in the bucket for 10 days? If so I wouldn't touch it with a ten foot pole. When you racked, the space formerly occupied by the beer was replaced with air and you know what lives in air. I would consider yeast sitting around for 10 days surrounded by 5 gallons of random air a high risk for infection. I've neglected to clean my primary for two days and noticed pellicle starting to form on the krausen ring (with the lid on tight). I wouldn't risk a brew cycle.

 

I wouldn't use it after 10 days either. I usually rinse my yeast from the fermenter within an hour and put it in the fridge minutes later. Even when in the fridge within a closed Mason jar, if there is any significant air space (more than an inch or two), you can get contamination. Happened to me several times.

 

Only 3 situations when I would be tempted to pitch a previous cake...

1. The OG of the first beer was < 1.045
2. Racking 1st beer and pitching 2nd occurred promptly < 10days from 1st pitch
3. I really liked the yeast & needed to brew a big beer

 

Okay, I misread that, no, don't reuse the yeast from an empty bucket that has been sitting without beer for any real length of time. Thanks @PortLargo for the clarification on that one.

 

I have a similar situation brewing (ha ha)
PLanning a pale ale, then roughly a week later an IPA.
I won't be dry hopping the Pale, so my thought was to take a Mason joar or equivalent (clean & sanitized, of course) and scoop a dose of the trub out to use for the IPA. You all are saying I should make sure that the jar is full as possible, right? Would boiled then cooled water be a good thing to top off the jar with? I started thinking about saving some wort from the PA, but then it would start to ferment, and even in the fridge, I don't want to worry about a jar bomb.

 

I would advise against using the whole cake, however, you can definitely use a portion of it without going through the process of rinsing etc. Although left for 10 days... not sure...

Everything in my (limited) experience, and from what "experiments" I have read about from other people, has led me to believe that rinsing the yeast is not required. Of course, this assumes that the yeast is healthy, and you didn't brew something crazy beforehand.

http://brulosophy.com/2015/03/02/sloppy-slurry-vs-clean-starter-exbeeriment-results/
http://brulosophy.com/2015/07/15/sloppy-old-slurry-starter-vs-fresh-yeast-exbeeriment-results/
http://brulosophy.com/2015/08/24/sloppy-old-slurry-no-starter-vs-fresh-yeast-exbeeriment-results/

 

I'll expand upon what @machalel has suggested.

Go ahead and reuse the yeast and don't bother with the rinsing. If your sanitation was good from the start you should have no problems at all. I started repitching my yeast slurries 30 years ago and the fact is you can even keep re-pitching through multiple generations of brews if your sanitation practices are what they should be.
After the fermentation, I save the slurry (in some of its own beer) in a foil covered flask in the fridge. When you re-pitch, you don't need to use the whole yeast cake (and in fact, really shouldn't)...except for stronger ales, 1/3 or 1/2 of the slurry is plenty. Ideally you should reuse it within a few weeks, but you can go as long as a month and a half (depending upon the strain); you'll just have to use more of the saved slurry.

You can rinse the yeast if you wish, but frankly, it is totally unnecessary to rinse the yeast before reusing it. I've experimented by doing it both ways...rinsing and not rinsing...and found absolutely no difference whatsoever in quality or performance of the yeast either way.
If anything, you may actually be risking contamination by rinsing it. I seriously recommend trying it both ways yourself...I believe you'll come to the very same conclusion.

By the way, with regard to that yeast which was given to me in 1985....I plated and saved it the following year (after it fermented 12 successive batches) and I have been re-propogating it for use ever since. And every time I re-propogate it, I still routinely re-pitch the slurries through an average of 8 or 9 generations without the rinse.
Doing so has never caused any problem.

 

I only do it on mixed cultures with Brett, as it will eat up autolysis.

 

Never used a yeast cake for fermenting a beer before, but I'll be trying it for the first time this coming Saturday. Following the recommendations from a previous thread, I'll be fermenting an English barleywine using the yeast cake from a currently-fermenting English pale ale. I'll be brewing and bottling all the same day, so I'm not terribly concerned with sanitation, though I'll probably err on the side of caution and use a spray bottle of StarSAN to give the primary fermenter a good dousing before adding the barleywine wort.

 

Has any one ever harvested yeast from primary, washed and re-pitched into secondary in order to dry out their beer?

 

No need. There will still be plenty of yeast in suspension, so if there's still work to be done, it'll do it in secondary.

 

Of the same beer? What would make you think that said procedure would make your beer attenuate further? It's the same yeast with the same fermentation dynamics.

 

I find that a better way to get lower FG is to do a diacetyl rest. Wait until you're a few points away from normal FG, then raise the temperature by as much as 10 degrees for a couple of days. You should be able to knock a few more points off your 'normal' FG. Or you could use a more attenuating type of yeast.

 

Raising the temperature should get you to the FG faster, but it really shouldn't take it any further at the end. People do forced fermentation tests (i.e. fermenting at a higher temp, similar to doing a diacetyl rest) all the time, because they are a reliable indicator of the FG that will eventually be reached at the normal fermentation temperature.

 

Are there any controlled tests of this, VikeMan? I know this is empirical, but I find that when I do this, I generally always go lower than the predicted FG for that yeast.