Oxygenate or not?

[Newsman]

So there's someone in a homebrew forum on Facebook claiming that aeration does nothing for dry yeast. Can anyone link to authoritative posts otherwise?

 

[DBhomebrew]

Check out the FAQs at the bottom of this Lallemand document. There's some nuance here.

Lallemand document

 

[Golddiggie]

Keep in mind, the stated (in the document linked above) 16p is 1.065sg. Which is NOT all that high on the scale. Basically the range where a ~6% ABV beer would start at.

 

[Newsman]

Keep in mind, the stated (in the document linked above) 16p is 1.065sg. Which is NOT all that high on the scale. Basically the range where a ~6% ABV beer would start at.

Thanks

 

[BrewnWKopperKat]

So there's someone in a homebrew forum on Facebook claiming that aeration does nothing for dry yeast. Can anyone link to authoritative posts otherwise?

Fermentis has similar information (generally no aeration needed on first use) in the "Tips & Tricks" brochure at their web site. There are special considerations for "high" OG worts and for sour worts.

 

[AlexKay]

While over-aeration is potentially a thing, and so one might think to avoid aerating dry yeast if you don’t need to, my money is on a little extra O2 not hurting anything.

 

[BrewnWKopperKat]

For normal strength worts: if I don't need to aerate the wort before pitching the yeast, that simplifies and shortens the brew day. For the dry yeast strains that I use, the dry yeast labs are currently recommending "no need to aerate" for normal strength worts. If you view them as an authoritative source of information, give it (skip aeration) a try.

On the other hand, since yeast nutrient often viewed as "cheap insurance" (but see this), aeration could also be viewed as "cheap insurance".

Perhaps, this (from one of those dry yeast labs), says it best:

Given the impact of yeast of the quality of the final beer it is recommended to respect the recommended fermentation instructions. We strongly advise [brewers] to make fermentation trials ...

 

[Golddiggie]

For normal strength worts: if I don't need to aerate the wort before pitching the yeast, that simplifies and shortens the brew day. For the dry yeast strains that I use, the dry yeast labs are currently recommending "no need to aerate" for normal strength worts. If you view them as an authoritative source of information, give it (skip aeration) a try.

On the other hand, since yeast nutrient often viewed as "cheap insurance" (but see this), aeration could also be viewed as "cheap insurance".

Perhaps, this (from one of those dry yeast labs), says it best:

There's also [at least] a handful of different ways to get oxygen into the wort. From the cheapest 'shake' method all the way up to pushing pure O2 into the wort through stones (a variety of ways there too). I like having the oxygen infusion happen as the wort leaves the plate chiller and is going into the fermenter. Minimal effort on my part. Lower OG brews get a lower Lpm infusion than higher OG brews.

 

[Oleson M.D.]

We never add oxygen artificially to the wort. Not required at all.

It was explained to us that even bubbling oxygen into the wort is mostly an illusion. The bubbles simply rise to the surface and dissipate into the atmosphere.

 

[CascadesBrewer]

There is a quote from an Escarpment Labs presentation that stuck with me. It is something like "Your goal is not to oxygenate the wort, your goal is to oxygenate the yeast."

The general theory is that oxygen helps a lot with yeast cells to build up their cell walls and reserves. Yeast produce a lot more energy in an aerobic state (but they produce little alcohol). I would be curious to learn more about the differences in dry yeast production and liquid yeast production. My understanding is that dry yeast are "interrupted" in a state where they have healthy cell walls, thus the need for oxygen is less critical. I tend to think that some oxygen is helpful for dry yeast, or at least I don't recall seeing evidence that it is harmful.

Personally, I have mostly moved away from any specific oxygenation of my wort, other than the oxygenation that occurs with the transfer into the fermenter. I am mostly using either dry yeast, or using a "Shaken-not-Stirred" starter. So in theory I have oxygenated the yeast in the starter and I am pitching healthy and active yeast. This strategy has been working well for me.

For years I used an aquarium pump with an air stone. I know this is not as good as pure oxygen. I stopped using this a few years ago after an infection and trying to limit possible infection sources. I tend to break it out only for high gravity beers, and I will give two rounds of oxygenation to those beers.

But I do see conflicting information on the original question. The liquid yeast companies tend to say "of course, all yeast should be oxygenated" and the dry yeast guys say "see how easy dry yeast is since you don't have to oxygenate!" The vast majority of studies or literature on the topic that I have seen are funded by yeast labs.

 

[VikeMan]

We never add oxygen artificially to the wort. Not required at all.

It was explained to us that even bubbling oxygen into the wort is mostly an illusion. The bubbles simply rise to the surface and dissipate into the atmosphere.

Some of the O2 does escape, moreso when oxygenation in an open fermenter, but some dissolves. It's not an illusion, because people have measured the dissolved oxygen afterwards. Here's one example:
https://wyeastlab.com/resource/home-enthusiast-oxygenation-aeration/

 

[BrewnWKopperKat]

But I do see conflicting information on the original question. The liquid yeast companies tend to say "of course, all yeast should be oxygenated" and the dry yeast guys say "see how easy dry yeast is since you don't have to oxygenate!"

Could it be that different scenarios for brewers yeast require different techniques for "best" results:

• "one and done" pitch of dry yest
• pitch and harvest of dry yeast
• "one and done" pitch of liquid yeast
• pitch and harvest of liquid yeast

 

[Oleson M.D.]

Al I know is we mostly use dry yeast, but harvested for XX generations. We NEVER add oxygen. And the ferments take off like a nuclear bomb. The trick is to use fresh, healthy and viable yeast.

 

[BrewnWKopperKat]

Al I know is we mostly use dry yeast, but harvested for XX generations. We NEVER add oxygen. And the ferments take off like a nuclear bomb. The trick is to use fresh, healthy and viable yeast.

With dry yeast (1st pitch), do you make a starter for the additional generations?

eta: are you willing to share details on your processes?

 

[Oleson M.D.]

With dry yeast (1st pitch), do you make a starter for the additional generations?

eta: are you willing to share details on your processes?

We do not make starters for any of our yeasts. The first pitch is dry, right out of the package. The yeast is always harvested. With a successive pitch, we do not make a starter. We brew often enough that the yeast is never more than a couple weeks from it's harvest date. And we keep our yeast slurry hyper clean. But some people tell me that makes no difference. And we always over-pitch. 1 qt per 5 gallons.

Correction: We did make a starter, one time. The yeast literally was coming out of the bottle, going down the front of the cabinets onto the floor. This was very early in the morning, and I got the mess cleaned up before my wife saw it. The yeast is Diamond Lager. Now we pitch it straight from the fridge.

 

[VikeMan]

And we always over-pitch. 1 qt per 5 gallons.

If I were pitching a quart of slurry per 5 gallons, I wouldn't add oxygen either, because the yeast aren't going to use much of it, if any, and the rest would simply oxidize the wort. The yeast don't need it, because they won't need to make sterols for cell wall division. But I wouldn't pitch that much yeast, either. Severe overpitching can cause some issues. Among them are excessive Acetaldehyde and Fusel Alcohols, and (faster) Autolysis.

 

[Oleson M.D.]

If I were pitching a quart of slurry per 5 gallons, I wouldn't add oxygen either, because the yeast aren't going to use much of it, if any, and the rest would simply oxidize the wort. The yeast don't need it, because they won't need to make sterols for cell wall division. But I wouldn't pitch that much yeast, either. Severe overpitching can cause some issues. Among them are excessive Acetaldehyde and Fusel Alcohols, and (faster) Autolysis.

For some strange reason, over pitching works very well for us. Even though many folks have told us it can't be done with good results. Especially on other brewing forums.

The flaws you mentioned have never been an issue in any of the beers we have brewed. I am not saying the beer we brew is always perfect. Had one beer that had a diacetyl problem. But that was addressed, and it was then drinkable.

 

[Craiginthecorn]

From Brew Your Own magazine

Oxygen: Oxygen is another essential component in yeast metabolism that is typically injected separately, but still important to mention. Oxygen/air is necessary for efficient cell division immediately after yeast pitch to ensure adequate cell population for fermentation.* The oxygen is used for the production of sterols and unsaturated fatty acids, which are important in maintaining membrane structure and integrity and synthesizing healthy membranes as cells divide. These sterols and unsaturated fatty acids act like stress protectants to the yeast cell — they reinforce the membrane to uphold yeast function and viability. On the other hand, oxygen deficiency can result in poor fermentation and a high amount of acetyl coenzyme A, which can lead to increased levels of esters. This further influences the overall flavor of beer.1
*Oxygen/air is not normally required for standard fermentations using active dry yeast on first pitch, because when dry yeast is produced, it’s in presence of copious amounts of oxygen and is therefore filled with sterols.