Fermenting on top of a primary yeast cake

So I have been knocking out some pale ales lately very quickly with my Safale 05. The fermentations are completing in less than a week and half in my basement. Was wondering if after I transfer to keg (no secondary, I love green beer!) I could reuse the yeast cake and my primary fermenter for a new batch directly on top of it. The yeast will only be at most two weeks old but I normally cold crash a day or two before transfer. Do I need to be rinsing this yeast or let it fly since it is so young and healthy? I am keeping my new wort temps the same as the yeast cake (letting the cake warm up for an hour or two). This method will be used for the same hop varities only so hop residue shouldnt be an issue.

Pitching directly to a yeast cake is generally held as bad practice and extreme overpitching.

You can easily use some of the slurry for the next batch, though. Washing is unnecessary. EarlyAmateurZymurgist made a solid post on why yesterday:
https://www.homebrewtalk.com/f163/conflicting-advice-lhbs-hbt-447056/index5.html#post5735086

The MrMalty calculator does have a "repitch from slurry" section:
http://www.mrmalty.com/calc/calc.html
(But EAZ gave some volume tips in the linked post as well, which are reasonably easy to follow)

Happy brewing!

I scoop out about a cup, store it in the fridge overnight and repitch the next day. Works well.

I like the scoop a little and repitch method best lol.. That other stuff was very confusing! Of course nothing about yeast is to understand. It is pretty crazy to think that the cell count can change in a packet of yeast before and after fermentation. I will say that before posting this I went ahead and put new wort onto an existing yeast cake and I have never seen a more aggressive fermentation. The fermentation took off in less than 30 minutes of pitching. Everything was at the same temp though.
Pretty intense...

I have done used a slurry before and it worked very well. Mr Malty has a "Slurry" option for this. If I remember correctly it was something like 1/2 cup of slurry for a 5 gal. normal OG batch.

If you do collect some of the yeast cake in a jar or something what is the reason for refridgerating it if you are using it in the next day or so? Isnt oxygen exposure best for yeast? Yeast packets always have you warm them up to room temperature before pitching.

jcorn said:

If you do collect some of the yeast cake in a jar or something what is the reason for refridgerating it if you are using it in the next day or so? Isnt oxygen exposure best for yeast? Yeast packets always have you warm them up to room temperature before pitching.

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While you're waiting to pitch into a new batch, you want to keep the yeast slurry (which is now "liquid yeast") as dormant as you can. If you let it sit at room temp with no food source, the cells will try to be active, starve and die off much faster. That's why liquid yeast is best stored cold.

I don't have much of a problem with pitching on a fresh yeast cake so long as the time period between racking and pitching is short (like a few hours or less) and you remove enough of the cake to avoid serious over-pitching. It's most useful when doing a really big beer like an RIS or a high gravity lager which would otherwise need a huge starter.

Ok I see now.. makes sense. So the cold crashing prior to transfer can only help the dormancy of yeast cells in the cake prior to collecting or "new wort" introduction. I am going to play around with reusing dry yeast once or twice. I like the idea of using such a fresh and healthy yeast cake. Even though the dead cells remain somewhat hidden inside of it.

So from what I am gathering Friday I can keg an amber I have in primary then use a sanitized pint jar and scoop out about a pint of the cake? I then would place in the fridge overnight and the next day(sat) I could let it get to room temp and pitch it in a batch i brewed that day? Sounds simple and a good reason to keep brews coming down the pipeline. How many times would you reuse the yeast? Thanks

I have read over many threads that 2-3 times max, before you want to think about using a new vial/packet. I recently have been reading Beyond the Pale by Ken Grossman of Sierra Nevada. The craft brewing industry also reuses plenty of their yeast to help the beers become more consistent. So if you are brewing the same style, its a great thing. I have also heard that you brew up, meaning if youre reusing, it needs to be an equal or higher alcohol content on the next batch, I am assuming to help hide any flaws or issues with the reused yeast. I'm interested in trying it myself soon.

mufflerbearing said:

So from what I am gathering Friday I can keg an amber I have in primary then use a sanitized pint jar and scoop out about a pint of the cake? I then would place in the fridge overnight and the next day(sat) I could let it get to room temp and pitch it in a batch i brewed that day? Sounds simple and a good reason to keep brews coming down the pipeline. How many times would you reuse the yeast? Thanks

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You might want to sanitize a measuring cup and use that to scoop the yeast into the sanitized pint jar. Measuring cups have better handles and you won't have to try to clean the yeast off the outside of the pint jar when you are done. :rockin:

Just a quick note to add here. I am currently drinking this beer that I reused a whole yeast (did this before knowing better) of Safale 05. It has very noticable flaws. There is somewhat of an alcohol taste to it and it has some weird estery flavor as well. I will definitely be sure to only use a 1/4 of the cake next time. That sucker did finish fermenting in like 3 days though. And took off less than 30minutes after new wort introduction.

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jcorn said:

Just a quick note to add here. I am currently drinking this beer that I reused a whole yeast (did this before knowing better) of Safale 05. It has very noticable flaws. There is somewhat of an alcohol taste to it and it has some weird estery flavor as well. I will definitely be sure to only use a 1/4 of the cake next time. That sucker did finish fermenting in like 3 days though. And took off less than 30minutes after new wort introduction.

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Those flaws you note are as likely to be from fermenting too warm which will be exacerbated by the big yeast cake. When that ferment got going so soon after pitching it had a lot of yeast cells which would naturally heat up the beer. Unless you have very good temperature control it likely got ahead of your cooling ability. The flaw you should notice is a beer that has a lower FG making for a drier taste and a thinner bodied beer. Here's someone's experiment with under and over pitching yeast. Note that the overpitch was 5 times what was recommended and yours was probably more like 4. http://sciencebrewer.com/2012/03/02/pitching-rate-experiment-part-deux-results/

I honestly pitch on top the cake regularly. Brew a 1.040 OG beer on 1/1, pitch S-04 or US-05, etc. Bottle/Keg on 1/15 while the 1.060 beer you just brewed is chilling. Make SURE you basement (or fermnentation chamber) is cool enough (especially with S-04) to maintain a minimum wort/beer temp around 63 F.

So y'all got me to wondering about my latest brew -- a Newcastle clone.

Background: I've had the privledge of brewing a couple of times with my LHBS owner (a very talented brewer), and he added his Pliny clone wort right on top of a yeast cake he had used at least 2-3 times before -- without removing any of the cake. He fermented in a 10 gal keg, transferring the fermented beer with CO2 into another keg right before dropping the new wort onto the old cake. He never opened the keg. Once the wort was in, we just shook the heck out of it, and away it went. That beer turned out GREAT!

Experiment: Recently, I did essentially the same thing with my NC clone; I brewed a 3 gal. batch, fermented in the primary carboy for 2 weeks and then brewed another one and dropped it right on the yeast cake within an hour or two without so much as a "by your leave." The yeast I used was Wyeast London ESB. I will add that I keep a close eye on fermentation temps and that I was only risking <$9 of ingredients. I bottled it on 12-13-13 and normally would not touch it for another month or so, but I couldn't resist after reading this thread. I just popped one to taste test, and it looked like this:



Results: Smells and tastes like all of my other NC clones (a little immature, of course). Crystal clear, too!

Bottom Line: I would not hesitate to do this again; however, I do not think I would do a third brew on top of a full yeast cake just to be safe as I believe there would be a lot of organic material available to potentially contribute off flavors. I would not hesitate to scoop out a pint jar and re-pitch a 3rd or even 4th time in the future, though. That might be an interesting experiment down the road (i.e. "how many licks does it take to get to the center of a Tootsie Pop) before the brew changes character...

The wort was around 65 when I pitched the yeast which was 63. I definitely wouldnt think 63-65 would be too warm of a fermentation for Safale 04? I think the problem is mostly from overpitching and dead cells.

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jcorn said:

The wort was around 65 when I pitched the yeast which was 63. I definitely wouldnt think 63-65 would be too warm of a fermentation for Safale 04? I think the problem is mostly from overpitching and dead cells.

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No, but correctly pitched S-04 can increase a wort's temperature 10 F in as little as 18 hours if not controlled. Over-pitched? Maybe 15 F.

Onkel_Udo said:

No, but correctly pitched S-04 can increase a wort's temperature 10 F in as little as 18 hours if not controlled. Over-pitched? Maybe 15 F.

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Oh yeah I am sure it probably could as long as the room it is in is room temperature or so. It was in my basement and I havent seen the basement get over 62/63 all winter long. Re-pitching dry yeast seems like a waste of time?

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jcorn said:

Oh yeah I am sure it probably could as long as the room it is in is room temperature or so. It was in my basement and I havent seen the basement get over 62/63 all winter long. Re-pitching dry yeast seems like a waste of time?

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If the ambient temp is 62 and the yeast raise the beer temp 15, then you fermented at 77 degrees. Before I had temp control I regularly saw ferm temps 10° higher than ambient from one packet of dry yeast.

cjgenever said:

If the ambient temp is 62 and the yeast raise the beer temp 15, then you fermented at 77 degrees. Before I had temp control I regularly saw ferm temps 10° higher than ambient from one packet of dry yeast.

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My ambient was 62 so I am guessing it never reached more than 66. When I brewed the summer my ambients were 70 and my fermentations stayed consistent around 70-71. Never saw it higher and I tested it alot. Maybe the yeast cake could have been warmer?

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Just pulled a pint off the caramel amber and pitched it on my house ale. Just scooped put in a clean pint jar let it sit for about 20 min during cooling then put it right in. Now we wait.

I would be afraid of under or over pitching from a scoop and not a wash. Wouldn't their be dead and stressed cells within the cake along with the trub that you carry over?
Also how do you know how much cake to scoop? Seems nearly impossible to measure cell count and whether you are scooping trub or yeast. Sorry I overanalyze everything lol

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jcorn said:

Sorry I overanalyze everything lol

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Very much so. Have you ever TRIED to ruin a beer by your ingredient choice? Outside of a few smoked malts, extremely excess roasted malts, etc...it is hard to ruin beer.

Onkel_Udo said:

Very much so. Have you ever TRIED to ruin a beer by your ingredient choice? Outside of a few smoked malts, extremely excess roasted malts, etc...it is hard to ruin beer.

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LOL. I've made a LOT of bad recipe choices that caused ruined batches. E.g. too much coffee, too much Aromatic Malt, too much mineral additions, etc. Nonetheless, recipe is right up there with sanitation in terms of critical issues for a brewer.

I have made a lot of bad recipes. Some I even dumped because they were so bad. Too much apricot puree on one for a magic hat 9 clone, a nasty vanilla and clove combination. I think it is very easy to screw up a batch of brew if you don't pay much attention to your recipe. Too high of fermentation temps/dead cells on re-pitch equals alcohol flavors from the cells. Too little of special grains and you have a terribly bodiless beer.

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This cascadian dark ale I just made came out so heavy on coffee flavor. I consider it ruined although I am sucking it down and trying to wash it down with keg hops of citra.

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Well in just 3 hours at 68 degrees on the sticker I have some movement.
I may close the vents in the room and let te temp drop a little. Tips?

Swamp cooler it if you are wanting to drop your temps. You can lower at least 3 or 4 degrees lower than ambient with one and a fan on it.

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