I’ve always heard you should repitch slurry to a higher OG beer but I recently did just the opposite when I used the yeast from a doppel bock 1.082 and racked my freshly brewed Vienna Lager, 1.054, onto the cake.
This is the third batch for this yeast. First made a big starter with it and pitched to a pilsner and it began to show signs of fermentation within hours. Then I racked the doppel bock onto the full cake and it had kreusen within 6 hours.
I also used the full cake for the Vienna figuring if the yeast was a bit stressed from the bigger beer it would help. Now almost 48 hours later there’s a light layer of bubbles on the surface. I’m not concerned that it won’t ferment. I think it’s getting going but this has obviously put the yeast under some stress and I’m a bit surprised frankly.
I recently pitched a 1.055 beer onto the yeast cake of a 1.090 IIPA. The yeast really didn’t seem to mind that much, I removed about half of the yeast cake but fermentation got going within a couple of hours. I personally don’t think we give the resiliency of yeast enough credit, they can take an awful lot of abuse and still keep going strong.
I think that’s one of those urban myths. I’ve pitched higher and lower and never noticed a problem or noticed anything different. I’m a firm believer that the yeast gets acclimated to your water and actually works better.
You’re exactly right. The idea that yeast mutate and start doing weird things is incorrect. What actually happens is they adapt to their environment. Yeast express different genes based on their environment, which can cause drastically different behavior based on some environmental condition. But once they adapt, their traits are fairly consistent from batch to batch.
That’s been my experience as well. I’ve pitched yeast from higher to lower gravity beers many times and seen no problems.
If fact, the only times I’ve seen any signs of “stressed yeast” has been when I’ve stored yeast cakes in the fridge too long (more than a month) and not made a starter, or when the previous batch wasn’t oxygenated enough.
The oxygenation issue is a bit counter intuitive, at least to me. It doesn’t seem to have any descernable effect on the beer that was under oxygenated, but it has a big negative effect on the lag time and attenuation of the next beer that the harvested yeast is pitched into.
I pitched my 34/70 from my .072 doppelbock onto my .058 Irish lager and it took off in under 8 hrs. It fermented strong and clean. So maybe something else is causing a slow start. What’s your yeast and temperature.
I was just speaking to my microbiologist; she surmises that with proper oxygenation of batch one, you’ll end up with overall healthier cells per volume of slurry than if you under oxygenate. So the oxygenation of batch one effects the ‘quality’ of the slurry pitched into batch two. Of course her speciality is bio-pharma and not yeast, so this is more of an educated guess than true understanding. Makes sense to my brain though.
That sounds like it makes sense. I think the online slurry calculators err on the side of over pitch though and I tend to over pitch a little more. I think Danny pitched on the full cake so there should definitely be enough yeast.
The explanation makes sense, but I just stumbled across the phenomenon. Had a great yeast strain going, was on the 5th or 6th repitch, and and I forgot to oxygenate the wort. Realized it a couple days later, but the fermentation was going fine so I didn’t sweat it. Next beer, the results were obvious, had to retire the yeast.
Then I repeated the results, again pretty much by accident.
Yeast is 2206 Wy bavarian Lager yeast. Pretty much my house lager strain. Generally starts up pretty quick and ferments clean and flocs well.
Thinking back on the brew day I may not have aerated the Vienna wort as well as I normally do. Ground water was colder so i could chill faster, had a bit less foam in the carboys than usual after the transfer but I did run the mix stir with the drill for a bit in each one.
Looking pretty grim at this point. I was thinking of getting some dry to pitch to it but the only dry lager yeast I’ve used is 3470 and it started up pretty slow on the first pitch.
This is correct… When you oxygenate the wort, you get much better cell reproduction so the overall yeast cake is made up of “younger” cells. If you don’t, the yeast won’t go through as vigorous of a reproduction stage, so you’ll have a lot more exhausted or dead cells in the later batch, which will certainly underattenuate or throw lots of off flavors. That microbiologist of yours nailed it!
I use 34/70 slurry a lot but I’ve found the slurry starts fast the dry takes some time to get going . That is why I thought about the high krausen pitch. Just to let you know this is all guess work for me. How about you get a couple of those smack packs or toss in the dry along with a fermenting starter with what you have.
That was my experience last time I used 34/70 too @brew_cat but I had a lot going on this weekend and didn’t have much time to spend messing with this. SO, I got 4 packs of 34/70 rehydrated and pitched them yesterday afternoon. This morning I have activity and a light krauesen forming. May salvage this vienna yet!