Yeast cake=old yeast

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deantheking101

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I know you are supposed to transfer off the primary after a month because the yeast will die and give you an off taste. But when you pitch onto a yeast cake are you not using the same yeast for 2+ months? Will i get off flavors?
 

homebrewdad

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I know you are supposed to transfer off the primary after a month because the yeast will die and give you an off taste. But when you pitch onto a yeast cake are you not using the same yeast for 2+ months? Will i get off flavors?
Actually, the "get the beer off the yeast cake because of off flavors" is outdated advice. Today's yeasts are much hardier. You'll note that pretty much all of the vets here recommend at least three weeks in primary - and many don't do secondaries at all.

You won't run into autolysis issues for quite a few months (I see 8 as a commonly mentioned number) unless you are making HUGE batches of beer (i.e. professional sized stuff).

Assuming that you do everything else you are supposed to do with the yeast cake, you won't have any issue reusing it.
 

gtlaw10

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typically a yeast cake (the leftover trub in the bottom of your fermenter) is only reused once or twice - because the cake rather quickly becomes unruly in size and full of dead cells. https://www.homebrewtalk.com/f163/pitching-trub-263190/
washing some yeast from the yeast cake and pitching this washed yeast allows you to reuse the same batch of yeast ~10 times before changes are apparent - there are too many chances of off flavors from overpitch, autolysis, infection, residual ingredients, etc for me to pitch onto the trub more than once.
 

Iqbal624

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What about all the proteins and stuff that settles to the bottom from the cold break and such. Is it ok to just repitch on top of that?
 

Piratwolf

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I've done about 8-10 batches where I merely split my trub--yeast & all-- into a couple of sanitized half pint jars, then repitch the appropriate amount into the next batch. No off flavors, no problems. Most recently I did, in order, a mild, an ESB, and an RIS, all using 1968 yeast according to the procedure above.

One caveat: I wouldn't use the whole yeast cake. That's severely over-pitching. And if you split the cake, you get many more generations. I haven't gone beyond 3 yet, but plan to experiment a bit this year :)
 

gtlaw10

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One caveat: I wouldn't use the whole yeast cake. That's severely over-pitching. And if you split the cake, you get many more generations. I haven't gone beyond 3 yet, but plan to experiment a bit this year :)
I believe that is what the OP plans to do.

What about all the proteins and stuff that settles to the bottom from the cold break and such. Is it ok to just repitch on top of that?
In theory, one has racked their beer off of that when transferring to primary. As for the bits and pieces that inevitably make their way into the fermenter/primary - this is why it is important to not pitch a malty brew on the cake from a hoppy brew, or a lighter brew on the cake of a darker brew.
 

Piratwolf

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Apparently there are off flavors associated with over- as well as under-pitching. That report is from reading, however, not personal experience.
 

acuenca

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Usually i'll make a starter from washed yeast for a 1045~1065brew then toss a >1085 brew on top of that cake....never had issues or off flavors....under pitching yes ..off flavors but over pitching, I think the issues become that some of the more subtle and complex yeast flavor s can't develop as well if the yeast can't replicate as much, ie over pitching...
 

MilesLong

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Over pitching yeast can reduce the amount of desirable esters in an ale...as well as leave some byproducts such as acetaldehyde that may be cleaned up in a full fermentation cycle...lol, kinda seems possible. I think I read somewhere that it is not even an issue under 400 billion cells pitched in a 5 gallon batch. If a smack pack contains 100 billion...thats a lot of yeasties
 

pjj2ba

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I know you are supposed to transfer off the primary after a month because the yeast will die and give you an off taste. But when you pitch onto a yeast cake are you not using the same yeast for 2+ months? Will i get off flavors?
According to Chris White (of White Labs yeast), the best yeast to save, are those obtained by top cropping during active fermention. He doesn't really recommend using yeast that are older than that. Now his book is really geared to the craft brewer and his guidelines are for getting the best quality yeast for subsequent fermentations.

Yes you can use older yeast perfectly fine, you just have to pitch a lot more as many are dead. This will impact the flavor - you might like it, you might not (some might not even care).

As to the myth of off tastes. The myth is that the flavors are OFF.
You will get flavors. Many folks like these, many are not as found, but not so much to call them off flavors. You have to really abuse the yeast (too hot, infection etc.) to get what most of us would consider off flavors
 
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