The book Yeast will tell you most everything you ever wanted to know about the subject. At the start, yeast eats up all available oxygen to reproduce. More yeast means a better and faster starting fermentation. The book recommends about 45 seconds of oxygen injection for the basic 5 gallon homebrew batch. I have been using our host’s oxygenation kit for some time with definitely noticeable results.
Although pure O2 injection is best method, according to the book anyway, any method to get air or oxygen in at the start of fermentation is a good thing.
It’s important to note however, that after that time, oxygen is a bad thing. Your fermented beer will oxidize and not taste as good.
@dmtaylo2 Can you tell us more about not needing to aerate dry yeast. That’s news to me too
As a bubble rises through your wort or fish aquarium it doesn’t really get smaller. Not THAT much oxygen is transferred. The key is to create the greatest surface area possible to maximize transfer. So thousands of micro bubbles through a diffuser creates a huge surface area when compared to the same volume in bigger bubbles
When brewing pale ale and such I just US-05. Everything else I’ll use liquid. That said I have used alot of other dry yeast with excellent results but for the original post I would recommend to any new brewer just use dry yeast to start and master the craft before worrying about the yeast. If your beer is coming out crappy it’s probably not because you used dry yeast
“The purpose if aeration is that the O2 is used by the yeast to synthesize sterols. Those keep the cell walls flexible to encourage budding.”
From another guy:
“The oxidative growth technique used to produce dried yeasts actually helps to stabilize the cells against the dehydration process, in part by increasing the production of these compounds (by up to 5 times).”
From Lallemand:
“The yeast contains an adequate reservoir of carbohydrates and unsaturated fatty acids to achieve active growth. It is unnecessary to aerate wort upon first use.”
Source:
And this is just one source of hundreds of others I’m sure.
I should probably run an experiment on this sometime. It would be super easy. I use dried yeast most of the time anyway. Split a batch, aerate the bejeezus out of half and leave the other half alone. Taste the final beers. Hmm. This experiment might be in my near future. Maybe.
I use both, probably about 60/40 liquid to dry. I keep a spare pack of both ale and lager dry yeast on hand always just in case.
Rehydrating dry yeast is another nuclear topic, like throwing rocks at a hornets nest. I do rehydrate, but I think I saw a recent expert opinion stating that the need to rehydrate is a myth also…
And for some of the same reasons @dmtaylo2 detailed above you do not need to make a starter with dry yeast. Just like oxygenating, it adds another unnecessary step. Pitch 2 or 3 packs for a big beer or >5 gallon batch as directed by a yeast calculator.
I did a side by side using US-05 wort from the same batch. 6.5 gal glass carboys with 5 gal in each. I rehydrated one packet and just dumped in the other. Fermentation started about the same time. Ended about the same although I don’t keep watch, just let it go a couple of weeks minimum. FG same. I did not notice any difference in the beer really and it wasn’t a very scientific test. I just wanted to know if rehydrating was worth my time an effort.
Bottom line was that unless it will be a high gravity beer, just dump the yeast in. YMMV
I read an article/ad in BYO by Lallemand and it showed scientifically that the dry yeast didn’t need O2. But it didn’t hurt either.
And @dmtaylo2 is correct in his cites as well as @denny. The dry yeast is produced with glycogen, nutrients, carbs, and fatty acids which means it doesn’t require O2.
It also showed no substantial scientific data to recommend rehydrating.
@Steve the ‘more is better’ is not always accurate. There are studies that indicate that too much yeast can create significant esters and off flavors as the yeast don’t replicate enough to clean up byproducts. @denny has a cite for this as well.
I NEVER used dry yeast. Then one day I did an impromptu brew and that’s all I had. US05 and it was so simple and no different from 1056/001. Now, I use it anytime a slurry gets old because I can pitch 2 packs for cheaper than liquid + starter with no prep.
34/70, diamond lager is great. And turns out clear as day.
@dmtaylo2 have you tried anyone of the new dry yeasts like the kolsch?
I’ve got the K-97 and S-189 going right now. K-97 seems really good, S-189 perhaps more bland, but they’re not totally finished yet. I imagine the new Lallemand Koln yeast is likely similar to K-97.
I agree, it is less about the cost these days…the price of dry yeast has risen substantially over the past 6-7 years. When I started the stuff was so cheap I remember thinking how the heck could they turn a profit ?
I’ve yet to rehydrate dry yeast and have had no issues related to that aspect. Other than keeping the hose end as high as possible when draining into the fermenter, I don’t do anything extra to oxygenate the wort. I do rock it gently and slowly to try to spread the yeast out. I pitched 2 packs of 05 to a 1.095 wort ad it fermented out just fine.
Gee I never wore a leisure suit but a leather leisure suit I’ll bet is worth some money. I had a friend who showed up in a purple velour leisure suit with platform heels once after watching the movie " Superfly" he thought he was the cats ass
. A leather leisure suit!