I pitched a pumpkin brown onto a once-used cake of WLP051 today. I just racked the previous beer off into a secondary and then racked the new beer directly onto the yeast cake in my primary. After aerating (well, stirring roughly), I put the primary away for a nice rest. I checked on it about two hours later to find the air lock already consistently popping. This is the first time I’ve re-used a yeast cake like this and I assuming there is nothing to be concerned about, but this is the fastest start I have ever experienced. Is this something unique to a ‘2nd generation’ yeast or to WLP051 or is it just because of the yeast population present after fermenting the first beer?
A general rule of thumb for average-gravity ales is that a yeast cake will contain about four times the yeast needed for pitching the next batch. So you’d expect to see a short lag due to over-pitching, especially if you usually under-pitch (i.e. don’t make starters).
OK, makes sense. You’re right, I usually don’t make a starter for anything under about 1.050. So, I’m used to seeing some action about 24 hours and a good, consistent pop at about 36 hours. I’ll have to keep this in mind and start using the slurries to maintain a yeast inventory.
