Advice on repitching over yeast cake.

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Vetal

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Hi Experts,

Just brewed a 5 Gallon batch of Munich Helles lager using Wyeast 2308 - and it is looking really promising. I have a Grainfather conical and I am cold-crashing for kegging later this week. I have enough ingredients to make a second batch of the same Munich Helles. I have read that some people simply re-pitch a second wort batch on top of the existing yeast cake. I have never tried this myself.
- Should I add a fresh batch of wort on top of the existing yeast cake? I had created a 3 Qt Starter, added yeast nutrients and also oxygenated with pure O2 (60 secs) - so I feel pretty good about my yeast health.
- Alternatively - should I wash the yeast - create a new starter - clean and sanitize my fermenter and then add fresh wort/pitch?
Also - I am concerned about the krausen ring that sticks to the upper edges of my fermenter. Should I clean this out before pitching the fresh wort? Would this create any off flavors?

Any advice is appreciated. Thanks.
 

Joshua Hughes

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I wouldn’t wash. Krausen ring not an issue assuming sanitation was good to begin with. I wouldn’t wash it. You will have an over pitch but I didn’t notice issues doing that. Scoop half out and save for another batch and pitch in what’s there.
 

odie

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The old beer is still in the fermenter? Fermenter still sealed up?

No need to clean anything. Just rack the beer into a keg and dump 5 gal of fresh wort into the fermenter.

Being a conical...does it have a port above the yeast or does all the yeast have to come out the bottom, followed by the beer? I would perhaps drain half the yeast out and save and then pitch fresh wort.
 
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Vetal

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The old beer is still in the fermenter? Fermenter still sealed up?
>> Yup - old beer is still in fermenter - all sealed up. I will be using a closed transfer to a keg. I do not plan to open the fermenter till my new wort is ready.

No need to clean anything. Just rack the beer into a keg and dump 5 gal of fresh wort into the fermenter.

Being a conical...does it have a port above the yeast or does all the yeast have to come out the bottom, followed by the beer? I would perhaps drain half the yeast out and save and then pitch fresh wort.

>> Grainfather Conicals have a yeast dump valve that have all the yeast come out of the bottom followed by beer. I havent harvested yeast via the dump valve yet - so not sure when I would have "half the yeast" ...
 

odie

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one or 2 bottom ports? What I'm asking is can you rack the beer without touching the yeast? Or MUST the yeast come out in order to get the beer out?

If you only have the very bottom port, dump all the yeast into small jars. Preferably 1/2 pints. Each one should be less trub and more yeast than the previous jar....until the beer starts flowing. That should be all that there is. Then rack the beer. Refill with wort and pitch maybe 1/2 pint worth of the best yeast slurry.

Now depending if you filtered all the wort BEFORE the fermenter, then you will have relatively little slurry coming out and it will be mostly yeast.
 

jdauria

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Yep, just pitch right on top of the old yeast cake and swirl it up to get it back the yeast back in suspension. The rule of thumb with pitching on cake is to do it either either similar color beers putting a dark beer on a light beer's yeast cake and not to put a light beer on a dark beer's cake. You don't want to add color or any roast notes to a lighter beer. Saying that, I have pitched a Helles on a Schwarzbier yeast cake before with no issues at all.
 

odie

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Yep...try to stay within the same type of beer or similar.

You can go light to heavy/dark without issues. But have to step it down the other way....Dark to med color/flavor...then follow with Med to light color/flavors.

But assuming all the old beer was racked out and the yeast cake is pretty clean, you could possibly take bigger steps back down.
 

henchman24

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This doesn't apply in this case, but I would add that if you dry hop the first batch, that can carry over to the next beer as well.

This can also be a really nice method to build up yeast for bigger beers without the hassle of a starter. I will make a Helles/Pils or similar and then step up to something like a Doppelbock. Or a blonde ale to move up to an imperial stout (currently have a blonde ale > ~12-13% RIS fermenting now). That mitigates some of the overpitching, though I've never really had issues with that before.
 

Beermeister32

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This will work fine, just make sure you chill the wort down so you aren’t shocking the yeast.

I pitch lagers at 48F degrees. If you have the space, I’d chill the wort and your fermenter with yeast cake down to matching temperatures if possible, then transfer and oxygenate.

Come to think of it, I’m not even sure I’d oxygenate if you are using an existing yeast cake. Your yeast are plenty in numbers and health, what a great way to omit one more source of wort oxidation,
 

odie

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This can also be a really nice method to build up yeast for bigger beers without the hassle of a starter. I will make a Helles/Pils or similar and then step up to something like a Doppelbock. Or a blonde ale to move up to an imperial stout (currently have a blonde ale > ~12-13% RIS fermenting now). That mitigates some of the overpitching, though I've never really had issues with that before.
had not thought about that but an excellent idea if you like big starters.
 

madscientist451

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I've dumped new wort right in the fermenter without cleaning it and it works fine. But I usually swirl up the yeast slurry and pour it to a sanitized jar, then use half of it in the next batch. Recently I've changed my yeast handling practice and just make a large starter, pitch half and save half and don't re-use yeast that has been used in full batch.
 

henchman24

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had not thought about that but an excellent idea if you like big starters.
I find it works really well for bigger beer, but I'm fairly lazy on actually making big starters.

I've dumped new wort right in the fermenter without cleaning it and it works fine. But I usually swirl up the yeast slurry and pour it to a sanitized jar, then use half of it in the next batch. Recently I've changed my yeast handling practice and just make a large starter, pitch half and save half and don't re-use yeast that has been used in full batch.

When I actually make starters, I do the same. I make a ~2l starter and pull off a smaller mason jar off to store for the next go round. Works like a charm and don't have to deal with washing yeast or worrying about complete sanitation when cleaning out the yeast cake. When I need to make a beer with that yeast I just decant and start the process all over again.
 

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