Using too much yeast cake?

[raymarkson]

So I have noticed that when I use too much slurry from a yeast cake, I get off flavors in my beer. When I re-pitch the slurry, I usually use half of the yeast cake from the previous batch in a new five gallon batch. Is this too much? I detect what I think are fusels in the resulting beer every time I do this.

In my last batch, for example, I took half of the Nottingham cake from a cream ale (OG 1.040) and then put it in a Pale Ale (OG 1.055). Fermentation took off in about twelve hours and finished in about five days. I controlled the temperature the whole time at 66F. The final beer had what I thought were fusels in it. A beer judge confirmed this for me in his notes after I submitted this beer into a competition.

It seems that I've read on this forum that a lot of homebrewers will pour a new batch on top of the whole yeast cake with good results.

So my question is have others noticed issues when re-pitching too much yeast cake?
Also, if I do want to try this again- and I'm not sure that I do, how much yeast cake would be a proper amount for say 5 gallons of 1.055 beer?

 

[jtratcliff]

Half the yeast cake is probably an overpitch... depending on how soon you use it....

Do your off-flavors synch up w/ over pitch flavors?

I'm not sure, but I think over pitch is better in general to under pitch (depending on style)...

I generally swirl up my yeast cake (w/ added distilled water if necessary) then divide into
4+ 1-pint jars....

Each of those 1-pint jars seem to be plenty of yeast to ferment a new batch...

You could probably get by w/ 1/5 to 1/4 of a freash yeast cake... Have you plugged
your numbers into a yeast calculator?

 

[RM-MN]

In my last batch, for example, I took half of the Nottingham cake from a cream ale (OG 1.040) and then put it in a Pale Ale (OG 1.055). Fermentation took off in about twelve hours and finished in about five days. I controlled the temperature the whole time at 66F. The final beer had what I thought were fusels in it. A beer judge confirmed this for me in his notes after I submitted this beer into a competition.

Try a batch where you pitch 1/4 of the cake and control it at 60 instead of 66. When you use 1/2 half the cake you are pitching so many cells that they tend to get overactive (which produces fusels) and it becomes difficult to control the temperature of the beer. Even with a controller, you may not be keeping the temperature where it belongs. Is the temperature controller in a thermowell or attached directly to the side of the fermenter or does it only control the temperature of the location where the beer is fermented?

 

[raymarkson]

Try a batch where you pitch 1/4 of the cake and control it at 60 instead of 66. When you use 1/2 half the cake you are pitching so many cells that they tend to get overactive (which produces fusels) and it becomes difficult to control the temperature of the beer. Even with a controller, you may not be keeping the temperature where it belongs. Is the temperature controller in a thermowell or attached directly to the side of the fermenter or does it only control the temperature of the location where the beer is fermented?

The controller was set 59F-60F. The thermometer on the side of the carboy was indicating that the beer was at 66F.

 

[raymarkson]

Half the yeast cake is probably an overpitch... depending on how soon you use it....

Do your off-flavors synch up w/ over pitch flavors?

I'm not sure, but I think over pitch is better in general to under pitch (depending on style)...

I generally swirl up my yeast cake (w/ added distilled water if necessary) then divide into
4+ 1-pint jars....

Each of those 1-pint jars seem to be plenty of yeast to ferment a new batch...

You could probably get by w/ 1/5 to 1/4 of a freash yeast cake... Have you plugged
your numbers into a yeast calculator?

I am not totally sure what all of the over pitch flavors would be. And, although I do use the Mr. malty calculator when I make starters, I have not really used it for yeast cake re-pitches.

 

[RM-MN]

If the controller is in a themowell or attached to the side of the carboy with an insulating layer over it the wort temp should be almost the same as the controller temp. If your thermometer on the carboy showed 66 at one time, there may have been a time when you were not watching that the temperature spiked to 70 or higher, enough to create minor fusels.

 

[cefiro355]

I generally get around 4 brews out of slurry from 5 gallon. I try to get around 120ML ish of yeast (there's a calc in bsmith). If I'm in doubt i'll just do a 1000ml 24 hours in advance.