I keep hearing about overpitching as causing off flavor issues. If I keg a beer, and then I make a new beer and use the yeast cake from the beer I just kegged, is that an overpitch? The yeast cake would seem to me to have far more than the 11 grams of yeast that I pitched to start the previous batch. Am I wrong? And at what point does it become overpitching?
It really depends on the gravity of the beer you’re using the cake for. Generally speaking you can use 1/3-1/2 of the yeast cake for a similar gravity beer.
However, I’ve used the full cake plenty of times because I was too lazy or didn’t have a spare jar around to harvest the yeast.
Overpitching on a homebrew level is really not much of an issue from what i’ve always been told and experienced.
I often ferment a pale ale then schedule a stout to brew the same day I keg the pale ale and rack the stout right on top of the full yeast cake. About the same gravity on both beers. Have not experienced any issues. Have not gone to any additional steps past the two ferments, mainly because that gets me enough beer for a while.
If you plan to use the same fermenter the yeast is in I would suggest racking the beer off and into your keg immediately before filling with the fresh wort. It will help prevent any infection.
There are some that say it isn’t if you will get an infection with this method, it’s when. I have not had one yet but don’t do it very often. It’s pretty easy to just save some yeast in a mason jar or something and start over.
The times I have racked right on the yeast cake it has been an explosive fermentation so have a blow off tube handy.
I’ve pitched directly on the yeast cake before. I have to say it makes me nervous. Not sure why decanting to a mason jar makes me feel more secure.