Help! I forgot to aerate the wort!

[philipCT]

...and now I'm three days in to the fermentation of my Imperial Stout and the activity is crashing big time. I looked in on it this morning and noticed that the bubbling has dropped off to once every 20 seconds. I didn't understand it, so I looked back at my brew-log notes and realized I hadn't aerated it before pitching the starter (DOH!).

So my question is: what do I do now??? Should I aerate it now? Aerate and pitch a new batch of yeast? Is there anything really wrong with doing that?

I haven't tested SG because I don't think it matters much at this point. I would expect it to be somewhere middle-ish after only three days anyway.

Any suggestions welcome.

 

[Ski12568]

I would take a reading just to know for sure.

 

[bobeer]

how did you get it into the fermentor? What size batch is it?

you can't really tell what it's doing just based on the airlock activity. Chances are you probably aerated it enough when you dumped the wort into the fermentor. Could you have aerated it more? Sure, but I bet your brew will be ok.

 

[seigex]

I don't think you have that much to worry about. When you fill your fermenter you are aerating it, and ale yeasties are top-fermenting and will pull out the o2 from the oxygen in the headspace. I didn't do anything specific to aerate on my current brew because I had issues with my oxygen stone, and it fermented fine.

 

[ArcLight]

I don't think you have that much to worry about. When you fill your fermenter you are aerating it, and ale yeasties are top-fermenting and will pull out the o2 from the oxygen in the headspace. I didn't do anything specific to aerate on my current brew because I had issues with my oxygen stone, and it fermented fine.

Aerating your wort helps initial yeast growth.
What you suggest will not aerate the wort much and has minimal benefit.

Now having said that, the yeast will still ferment, and if you pitched enough, your beer should be ok. If not, they may stall out a few points short of the desired final gravity.

Above all - DO NOT aerate your beer after fermentation is done.
That's a BIG no no.
It can impart off flavors such as a card board taste.

 

[seigex]

Aerating your wort helps initial yeast growth.
What you suggest will not aerate the wort much and has minimal benefit.

Now having said that, the yeast will still ferment, and if you pitched enough, your beer should be ok. If not, they may stall out a few points short of the desired final gravity.

Above all - DO NOT aerate your beer after fermentation is done.
That's a BIG no no.
It can impart off flavors such as a card board taste.

In 10 years, I can count on my hands how many times I've used an oxygen stone, yet I've hit my FG in all but a couple brews, and I've had no off flavors produced from lack of specific o2 aeration. Remember O2 is soluble to water at cooler temps, and as the wort cools it absorts o2 from ambient air, though not as much as if cold wort is aerated with a stone, as more surface area gets in contact with pure o2 instead of 20% o2.

Here's an interesting article that goes into the science behind when and how much o2 is needed by yeast from early stages to end states and how yeast have no problems surviving in anaerobic environments.

I'll leave you to read the main part of the article, but here is the conclusion:

So, the bottom line is that yeast does not generally respire, and it does not even need oxygen at all to survive and grow. Yeast does, however, need lipids to build cell membranes and in their absence will readily consume oxygen for their synthesis.

Aerating your wort may solve some fermentation problems, but remember that if you’re pitching a fresh, healthy yeast culture of the optimal size, aeration is usually not essential and may even be undesirable in certain cases. Most important, the level of dissolved oxygen necessary in wort to produce the best beer depends on the strain of yeast being used, its viability, the pitching rate, and the style of beer being made.

And to reiterate my main point, I have no issue with aerating wort... it's just not the end of the world if it's not done.

 

[Calder]

Dry yeast - don't worry, it needs minimal aeration.

Liquid yeast and no starter - you are screwed!

What did you do, what OG, what yeast, how did you transfer to bucket?

 

[ArcLight]

In 10 years, I can count on my hands how many times I've used an oxygen stone, yet I've hit my FG in all but a couple brews, and I've had no off flavors produced from lack of specific o2 aeration. Remember O2 is soluble to water at cooler temps, and as the wort cools it absorts o2 from ambient air, though not as much as if cold wort is aerated with a stone, as more surface area gets in contact with pure o2 instead of 20% o2.

You don't need to use an Oxygen stone. Doing the 60 seconds of vigorous shaking (no need to hold it, rock it on the ground) will add a fair amount of Oxygen. maybe not enough for a high gravity beer, but enough for a typical beer.

The yeast are generating CO2 and will force out some of the Oxygen in the head space. Fermentation is mostly over in a few days, and that wont be enough time to absorb all the trapped O2, thus your suggestion wont really aerate the beer.


The article you state needs to be looked at more closely.


>>So, the bottom line is that yeast does not generally respire,

Thats simply untrue. Its 14 times more efficient to respire than to ferment.
The cell generates much more energy by using Oxygen. This is important during the early stages.

>> and it does not even need oxygen at all to survive and grow. Yeast does, however, need lipids to build cell membranes and in their absence will readily consume oxygen for their synthesis.

This is true. You want to aerate the wort so that the cells cane grow at the beginning. (they need more membrane material in order to bud).



>>>Dry yeast - don't worry, it needs minimal aeration.

I still do the 60 seconds shaking. The dry yeast has more cells, but the extra Oxygen helps it out.

 

[worlddivides]

Dry yeast - don't worry, it needs minimal aeration.

Liquid yeast and no starter - you are screwed!

What did you do, what OG, what yeast, how did you transfer to bucket?

Screwed? Really? How?

I oftentimes use liquid yeast and no starter. I do aerate my wort by splashing it into the fermenter and sloshing it around inside, but I don't use anything special like an oxygen stone or a fish tank pump. And my beers always have very high attenuation (my most recent beer hit between 80% and 85% attenuation) and they taste great. The only time I have had any off flavors in my beer was with the very first beer I made. Other than that, no off flavors whatsoever.

 

[Calder]

>>>Dry yeast - don't worry, it needs minimal aeration.

I still do the 60 seconds shaking. The dry yeast has more cells, but the extra Oxygen helps it out.

I don't use dry yeast, but from everything I have seen, most dry yeast doesn't need O2. A pack of dry yeast has a lot more cells than a vial of liquid yeast, but it also doesn't seem to need any aeration as it already has everything it needs. As I said, I don't use dry yeast, so I can't say for certain.

 

[philipCT]

Thanks for the replies.

I transferred 6 gallons of chilled 1.102 gravity wort into an SS bucket via pump, and I intentionally let the hose splash the wort from the top of the bucket.

The yeast was 2 liquid 1028 smackpaks in a 3.5 liter starter. The paks had dates September but between that and the starter, I had calculated about 550bn cells, which is what Brewers Friend suggested for a high gravity pitch.

So I definitely have calmed down based on the above comments. I'll wait a few days more and then test SG. I am shooting for something around 1.035 as a final.

I was just freaked out because aeration using an aquarium pump has become core practice for me and I've been getting really good results. I especially wanted to do everything I could for a high gravity beer, and this is the highest I've ever brewed. So thanks for the support!

 

[ArcLight]

I don't use dry yeast, but from everything I have seen, most dry yeast doesn't need O2. A pack of dry yeast has a lot more cells than a vial of liquid yeast, but it also doesn't seem to need any aeration as it already has everything it needs. As I said, I don't use dry yeast, so I can't say for certain.

If there are enough viable cells, then ok. If not, then the 60 second shake can be beneficial.

Why not do the 60 second shake? I don't understand the resistance to doing this? It's one simple step on top of a 5 hour brew day, and a later bottling session. And it can help make better beer.

 

[lhommedieu]

Your dilemma recalls the oft-repeated "Brewers don't make beer. Yeast does."

If you've pitched the requisite amount of yeast within the correct temperature range, then the yeast will do their job.

A simple experiment to perform is to make the same recipe again. Aerate the next batch and compare the OG to the FG of this batch with the readings of your initial batch.

I agree that aeration contributes to cell membrane health and cuts down on lag time. I find that it is less crucial for low- to medium-gravity ales; yours is higher, of course, but I think that the definitive factors are pitch rate and fermentation temperature.

 

[Calder]

If you've pitched the requisite amount of yeast within the correct temperature range, then the yeast will do their job.

I agree that aeration contributes to cell membrane health and cuts down on lag time. I find that it is less crucial for low- to medium-gravity ales; yours is higher, of course, but I think that the definitive factors are pitch rate and fermentation temperature.

Aeration is there to help with reproduction. If you pitch the correct amount of liquid yeast with zero aeration, you will get very little reproduction. The result will be that you will be fermenting with roughly one sixth of the yeast you should have.

Sounds like the OP did get some aeration, and had a decent pitch, so may be fine. If it does get stuck, his best option would be to brew a smaller beer and then rack this one onto the cake of the smaller beer.

 

[ArkotRamathorn]

If there are enough viable cells, then ok. If not, then the 60 second shake can be beneficial.

Why not do the 60 second shake? I don't understand the resistance to doing this? It's one simple step on top of a 5 hour brew day, and a later bottling session. And it can help make better beer.

For the sake of this discussion no one is saying " don't aerate your wort by splashing/shaking/oxygen stone". So no one is saying you are wrong.

We are qualifying our responses that it's not life or death in the situation the thread starter brought up. He pitched a huge starter in the wort and I am assuming it was a stir plate starter so the yeasties have built up really good sterol stores before pitching. As well there was probably some splashing Ana shaking during his transfer, there's almost always some dissolved oxygen gained during this, true it's not perfect. For the sake of the thread though it's probably not going to be an issue for the thread starters beer, it'll probably turn out fantastic based solely on the big healthy starter.

I would even put a couple dollars down that his/her beer is already at final gravity. No one is saying you are wrong arclight, they are saying though "the world is not ending, your beer will be fine".

 

[cjgenever]

Don't drink until you've pitched your yeast.

 

[cjgenever]

Thanks for the replies.

I intentionally let the hose splash the wort from the top of the bucket.

This is aeration.

You pitched a decent, hopefully healthy, starter. You aerated your wort some, just not as much as might be preferred. It's probably just fine

 

[masaba]

Someone did an experiment where they brewed the same beer and pitched the same amount of yeast into 3 different batches. One was aerated with pure O2 through a stone, one was shaken for 2 minutes, one was just pitched with no shaking or stone. They all attenuated to within .002 of one another, which is probably within the standard error of this experiment anyway. So, in summary, if you pitched a proper size starter I wouldn't worry about whether or not you aerated the wort.

 

[ncboiler]

how did you get it into the fermentor? What size batch is it?

you can't really tell what it's doing just based on the airlock activity. Chances are you probably aerated it enough when you dumped the wort into the fermentor. Could you have aerated it more? Sure, but I bet your brew will be ok.

Pretty much this. I forgot to aerate the first batch I made and it turned out fine. Don't read too much into the airlock activity.

 

[philipCT]

For the curious, I checked SG last night and it's already at the predicted FG of 1.031. So I guess if FG is the only measure of a successful fermentation, I'm good. I'm just thinking that off flavors are still a risk, however, the hydrometer sample was insanely delicious, so I'm not real worried.

 

[philipCT]

Update on this: this was an imperial stout. I made a starter, but it wasn't ready to pitch when I finished brewing, so it sat quiet in an ss brew bucket for a day. Then I pitched the starter without aerating it.

The beer achieved expected terminal gravity at about 1.024. After aging it for a few months, I've been drinking it with friends and everyone agrees it's insanely delicious with soft, complex coffee, chocolate aromas and flavors.

When I brew this again I will do exactly the same thing - no aeration before pitching.

Honestly, I'd like to split the next batch, aerate half of it and not the other. Then compare. I can't imagine it improving much over what I got.