I highly recommend “Yeast” by Chris White and Jamil Zainasheff. It talks a little bit about aeration and it references a study that shows that VHG (very high gravity) beers, would benefit a great deal with adding a 2nd dose of oxygen 12 to 18 hours after inoculation.
I wanted to figure out what the study considered “very high gravity” so, I read the study and turns out a VHG beer is one at or higher than 18 PLATO (1074 OG). I didn’t really think 1074 was “VERY” high… oh well…
Adding a 2nd dose of oxygen around 12 - 18 hours will reduce fermentation time by 33% and reduce acetaldehyde and diacetyl production for much tastier beers.
I’ve been thinking recently about additional aeration as my higher gravity (1.09+) beers are taking around three weeks to reach a stable FG. I always forget yeast nutrient, but I added it last time to the same effect.
My other thought is that I should scrap my yeast harvest and go back to a fresh culture. Last batch had a big pitch from an active starter and still seems to have some activity. I need to pull a gravity sample this weekend.
I’ve never aerated after fermentation has begun and am leery of doing so. Anyone on the board do this regularly?
Thank you for posting that article. Another interesting thing that caught my eye was Figure 2, which shows the dissolved oxygen levels vs. time when using pure O2. It is interesting to compare that to measurements that Gregg Doss of Wyeast made and presented in The Meaning of Life According to Yeast: http://www.bjcp.org/cep/WyeastYeastLife.pdf. The results that Doss presents agrees very well with what is in Figure 2 of that paper.
I’m going to have to pick through the paper and see what other interesting tidbits are in there.
I have been considering doing a constant aeration/oxygenation for the first 24 hours of fermentation for big beers >1.080. Either by stone/aquarium pump, or stone/O2. My current thought is an aquarium pump with constant low level aeration to encourage yeast propagation.
Just finished the book. It’s a good read. Lots of information without getting too technical. Found the info on additional O2 interesting. I’ve roused yeast before which would add oxygen, but didn’t really think much about that aspect.
The aquarium pump idea might put pathogens into your wort. You’ve gone to a lot of trouble to keep your beer sterile. After all, fish pumps grab unfiltered air and shove it into your beer, who knows whats in the air.
It’s better to use a bottle of O2.
I brew very few beers bigger than 1.070 but I use oxygen tank and stainless aeration stone quite often anyway. I go with a short 30 second application, cap the carboy and rock it hard for a couple minutes. Seems to work a lot better than just rocking it without the O2. Beers seem to start quicker and ferment out sooner with less chance for diacetyl than when done without.
I gave up the oxygen injection by stone and simply use a stir paddle on an electric drill for about 3 minutes straight for most beers I make (not many over 1.065). A really big beer may benefit from a short blast of straight O2 after a few hours while still in the respiration phase, but I would fear introduction of more pathogens with the stir paddle at that point.
FWIW I have that book as well. Loved it and learned a lot from it, but need to reference it more often for things such as this. I recall the information on starters and yeast propagation is great. I have no plans for a lab, starting a bank, or counting cells but it’s worth having the information and understanding it anyway.
Think it would help with something like a 1.080 Dopplebock style done with Chico ale yeast?
