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I'm brewing a 3G batch of Imperial Stout tomorrow and I don't have a foolproof aeration procedure. Back when I started brewing I read that you can also use olive oil to aerate wort in very small doses. Has anyone tried this before? Or should I shake the absolute shit out of the bucket after I pitch?

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It doesn't aerate, rather it's used instead of aeration.

Yes it works. Fermentation is a bit slower, FG could end up slightly higher.

If you're worried about not having enough O2 dissolved in the wort you could do both.

What's your planned OG?

Transmitted from the hop-phone.

Greg,
My OG will hopefully land around 1.095. Btw, I'm drinking a pint of the "new" Uncle Leo's IPA and it's fantastic. I detect more late addition (he said sarcastically)?

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jtmwhyte wrote:Greg,
My OG will hopefully land around 1.095. Btw, I'm drinking a pint of the "new" Uncle Leo's IPA and it's fantastic. I detect more late addition (he said sarcastically)?

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I'd shake the shit outta that and add a tiny drop of OO. OO thesis attached!

That's good news on the IPA, I still haven't got a taste of it yet so that's great to hear. We pretty much doubled up on the hops, re-adjusted the water treatment and integrated more malts For the first batch out of the gate, we sort of had to make do with what we had for raw materials.

Hey that's cool! Thanks Nash! I always called bullshit on the whole OO thing, but it seems I should consider the aeration/oo combo. I'll try reading the doc again when I haven't just finished a couple pints of X's IIPA and large words are comprehensible.

akr71 wrote:I always called bullshit on the whole OO thing

Science.

That's right.

I've used this method in the past great results.

So quite literally, just "a drop" of OO?

A drop is too much

Transmitted from the hop-phone.

I think in the paper they were using 1 mg/ 25 billion cells. I'm just guessing, but I'd put a drop of water somewhere around 100 mg. OO would probably be a little more as it is more dense.

I'd probably just dip a pin head into OO once or twice to give this a shot.

I used to burn off a twist tie and use that.

The olive oil method seems interesting, however, to test it in a home brew setup you would have to consider how the wort is cooled and how it is transferred to the fermentor.

I personally don't shake my primary, nor do I stir it vigorously. I cool my wort in my kettle using an immersion chiller with mixing of the wort then transfer it to the primary with 'splashing.' Once liquid is cooled it doesn't take much to saturate it with oxygen (well as much oxygen as you can saturate 20°C 'water' with at 1 atm pressure using air).

This method potentially produces slightly inconsistent degrees of oxygenation in my wort (I don't know as I do not have a dissolved oxygen meter at home), however, I have not had any problem obtaining vigorous fermentations with short onsets that drive the SG to the expected endpoint.

To experiment with the olive oil method at home I would suggest transferring the wort while still hot (closer to boiling the better) to the fermentor as hot water doesn't dissolve oxygen well. Cool the wort in the fermentor with little to no agitation. This should result in a near anaerobic wort which would require the addition of olive oil to shorten the lag phase of the yeast and drive fermentation.

Just my two cents. Perhaps I'll test my oxygenation method and the addition of shaking next time I do a 10 gal batch to see if it reduces that lag phase and produces lower SG beer.

-Kevin

For those who are unaware (as I was until fairly recently), dry yeast doesn't require aeration of the wort.

If you're referring to using liquid yeast, or re-pitching, aerate on

That's really interesting about dry vs liquid yeast. I've only used liquid yeast once. Do you have any idea why liquid requires aeration and dry does not?

-Kevin

This is from the Fermentis site:

Does the wort need Oxygenation / aeration?
As the yeast is grown aerobically, the yeast is less sensitive on first pitch. Aeration is recommended to ensure full mixing of the wort and yeast.

A little better from Lallemand:

I always aerate my wort when using liquid yeast. Do I need to aerate the wort before pitching dry yeast? No, there is no need to aerate the wort but it does not harm the yeast either. During its aerobic production, dry yeast accumulates sufficient amounts of unsaturated fatty acids and sterols to produce enough biomass in the first stage of fermentation. The only reason to aerate the wort when using wet yeast is to provide the yeast with oxygen so that it can produce sterols and unsaturated fatty acids which are important parts of the cell membrane and therefore essential for biomass production. If the slurry from dry yeast fermentation is re-pitched from one batch of beer to another, the wort has to be aerated as with any liquid yeast.

I've wondered abut this before. How would the manufacturers' "aerobic production" of dry yeast differ from the constant oxygen supplied by culturing yeast on a stirplate?

A stir plate provides very little oxygen to the culture as compared to an industrial aerobic fermentor that would be used to culture yeast.

In a flask on a stir plate agitation of the culture is not very turbulent and as CO2 is developed (which is heavier than O2) it will form a blanket over the culture and impede O2 transfer. An aerobic flask culture is always eventually limited by O2.

An industrial fermentor supplies a continuous stream of sterile air or pure O2 to the culture by sparging it through the media from the bottom. Agitation by impellers further reduces the size of these bubbles and mixes the culture giving excellent O2 transfer. Eventually O2 transfer could be limiting here as well, however, the culture can grow to much higher density before this happens.

-Kevin

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