Aeration Of Wort

[jason]

Hi

Could someone tell me how they aerate their wort prior to adding the yeast. As I need some ideas. Could I use a fish tank aerator? Also, how long should the aerating step be, before adding the yeast.

Thanks,
J

 

[Ross]

Jason,



An aquarium pump will work fine - best to pump the air through a s/s airstone for about 10 mins in a standard beer (longer for a stronger brew). Both items available through sponsers here or maybe your local aquarium/hb store.



cheers Ross

 

[hopmonkey]

i simply run wort from hopstrained tap, through tubing to fermenter, alowing it to freefall into fermenter.
This gives a lovely mousey head and a bubbly airlock and active ferment within the hour.
I do pitch a 2l starter everytime as well.
Simple! (just like me!)

 

[Kai]

I just drop the wort from one vessel to another.

 

[DJR]

I use the no-chiller method, and use the tap on the 20L jerry to drop the wort into the fermenter. I use the bottling tube with a 4cm piece of tubing on the end with some holes cut out of it on the sides. The wort runs past the holes which act as venturis, putting air into the wort, like a tap aerator does with mesh. The aeration foam is unbelievable with this method! Not really suitable with doing kit brews though as you need to have it in a jerry or other vessel, for that i'd use an air pump and stone.

 

[Keith the Beer Guy]

My standard practise has been to drop my wort, 3 to 4 feet, from one fermenter to another.

However, after recent conversations with several people, especially Gough, and doing some reading I am almost at the point where I agree with the idea that "homebrewers have been over-pitching to compensate for not aerating their wort properly.

On the weekend I brewed an imperial stout (OG 26 deg plato), and used for the first time a stainless steel aeration stone (2 micron from grain and grape). I was struck by how fine and tightly packed the the foam that was produced was. Whether it was the viscosity of the brew or a regular feature I dont know, but it was amazing - just an inch or an inch and a half of dense foam sitting on the top of the brew.

I pitched a 150 mls of yeast slurry. My brew kicked off in record time for me, less than an hour later.

So in conclusion, I'm on the verge of agreeing that better aeration is a significant improvement but have to brew a few more beers before I will wholeheartedly argue the point.

Happy Brewing,

Keith

 

[hopmonkey]

what are the drawbacks of over pitching a less well aerated wort compared to 'normal' pitching of a well aerated wort.
Will we be seeing a flavour difference in the finished brew?
I know the textbooks say overpitching causes low viability of yeast at the end of fermentation due to fewer new cells being produced. (ie yeast cells reach a maximum qty in wort, be it mostly pitched cells (overpitched) or a combo of new and old (normal pitching).) does this lead to (bottle) priming issues due to insufficent yeast? Is it a problem for kegged beers?
On a sidenote most of the larger brewerys i have visited, fill their fermenter, usually yorkshire squares, using the 'squirt it in from a height method' no additional aeration appears to occur, although i could be wrong.
Any thoughts on this?

 

[Goose]

I never used to take wort aeration very seriously until I had a few stuck ferments and extremely slow starts. Since then I've been using this paint stirrer attached to an electric drill, 60-90 seconds and I have a super churned wort. Since then I've noticed much more rapid starts to my fermentations....

 

[RobW]

Does anybody have info/experience on how long a wort will stay aerated?
ie: if I aerate between the CFC & the fermenter with a venturi setup but delay pitching, how long do I have before I need to aerate again.

 

[doglet]

RobW

I would guess that it would be best to aerate the wort just prior to pitching your yeast otherwise you risk oxidation of your wort.

Anyone else....

 

[Borret]

I seem to recall reading dissolved oxygen can dissipate in as little as 2 hrs but I cannot remember where I read it. So the great american slogan of 'go early, go often' is best left alone in this case. Airate (or oxygenate if you have the means) as close to pitching as possible.

It would also stand to reason that just like co2; the solubility of oxygen in wort is also reliant on the temperature. So thinking outloud- it should be easier to get better saturation at lager pitching temps than ale pitching temps?...

Brent

 

[bergerac]

From what I remember from my days studying aquaculture, the lower the temperature the more oxygen water will hold. You can over oxygenate water but the extra oxygen will only stay in the water for a certain amount of time before it disapates if it is over the amount that the water can hold for that temp. So the warmer the wort the more oxygen you are going to loose due to it disapting. I can't exactly remember the time frame this occurs over thought but I imagine it would be fairly quick.

 

[jason]

Ok, so it seems that aeration is very important. If i was to get an aquarium aerator (they seem pretty cheap), does anyone have any ideas on whether i need to use a air filter for the aerator and if so what type, also would it be necessary to use an air stone or could i just put the hose attached to the aerator into the wort and let it bubble away.

 

[bergerac]

How safe are aquarium air stones? Being full of tiny holes I can imagine them harbouring a fair bit of bacteria and being fairly hard to sanitise. On top of that they are not realy that effective at getting getting oxygen into the water as the bubble size is too big. I'm sure though that someone has found something easy to clean with a small bubble size.

Personaly I plan to use the whisking attachment to our small hand blender. The best way to get oxygen into water is to maximise the surface area between the two either by breaking the water into small drops and passing it through the air or breaking the air into small bubbles and passing it through the way (preferably under pressure) and the whisk should break up the the wort nicely.

 

[Trent]

I have just started using medical grade O2 with a 0.5 micron diffusion stone, but I have to admit, after hearing quite a few people say that a .5 micron doesnt really foam up, it is more like a "white powder" swirling through the brew, and hearing what Kieth just said about his 2 micron stone, I am half convinced I am doing something wrong. My 0.5 micron was from grain and grape, and I get a really thick layer of large bubbles, rather than a dense layer of fine bubbles. Havent really noticed any difference yet to using my hand held electric whisk, like Bergerac, but I have only done 2 brews with em, my bitter, which fermented out in 3 days (and was racked to secondary on Tues), and my ill fated brown ale that I just pitched at about 11.30am today. Will let ya know if I find any difference.
All the best
Trent

 

[Ross]

Trent, the set-up you have will work fine - excellent in fact.

Bergerac, The S/S airstones work great, the bubble size is fine & far more efficient than splashing etc. Sanitising is easy - you are blowing air through them so no wort is entering the stone, I lift mine out the wort & put them into a little non-rinse sanitiser with the pump still going for a minute - works fine.

Jason, Air filter is not really necessary, just make sure the pump is sat on a clean sanitised surface - airstones are cheap (from $10.00) & work far more efficiently than just running the line in.

Cheers Ross

 

[Borret]

Trent ,

I have never had a fine foam layer either. When I use it I get closer to a volcano that grows and climbs out the top of the carboy with largish bubbles.
Wort construction may make a difference here though. I haven't used it since I started AG.

Brent

 

[Rocket]

I have been using dried yeast lately so I havent needed to aerate. But last weekend i used a liquid yeast, first time in ages. I didnt aerate my wort but gave my 1lt yeast starter a good shaking before adding it and within a day it was going silly.
I know yeast takes up the oxygen to multipy but if you have a good yeast count to start with is it necessary to oxygenate?

 

[goatherder]

I have been using dried yeast lately so I havent needed to aerate. But last weekend i used a liquid yeast, first time in ages. I didnt aerate my wort but gave my 1lt yeast starter a good shaking before adding it and within a day it was going silly.

You still need to aerate the wort, regardless of dry or liquid yeast.

I know yeast takes up the oxygen to multipy but if you have a good yeast count to start with is it necessary to oxygenate?

This is a good question. If you pitched enough yeast to ferment out the entire wort you would technically not need to oxygenate the wort. BUT, yeast produce esters during their growth phase which form an important component of the final flavour profile of your finished beer. If you didn't oxygenate, you wouldn't get these esters and your beer would suffer for it. This is especially true of beers that have the ester profile as a highlight - weizens, belgians, english ales etc. In fact, some people will recommend under pitching on weizens and belgians in order to emphasise the banana esters which are produced during the yeast growth phase.

Try this on your next batch - keep everything the same as the previous batch except aerate your wort. See if there is a difference and tell us about it.

As for aeration, wyeast did some work on the effectiveness of different aeration techniques. Taking out the option of a pure oxygen system, the best methods were:

aquarium pump with airstone for 5 minutes
shaking the wort container vigorously for 40 seconds

The surprising result was that these two methods gave equivalent dissolved oxygen in the wort. So the good news is if you haven't got an aquarium pump and airstone setup you can exert a bit of energy and get the same results.

edit: spell

 

[BottleBitch]

I have been using dried yeast lately so I havent needed to aerate. But last weekend i used a liquid yeast, first time in ages. I didnt aerate my wort but gave my 1lt yeast starter a good shaking before adding it and within a day it was going silly.

You still need to aerate the wort, regardless of dry or liquid yeast.

I know yeast takes up the oxygen to multipy but if you have a good yeast count to start with is it necessary to oxygenate?

This is a good question. If you pitched enough yeast to ferment out the entire wort you would technically not need to oxygenate the wort. BUT, yeast produce esters during their growth phase which form an important component of the final flavour profile of your finished beer. If you didn't oxygenate, you wouldn't get these esters and your beer would suffer for it. This is especially true of beers that have the ester profile as a highlight - weizens, belgians, english ales etc. In fact, some people will recommend under pitching on weizens and belgians in order to emphasise the banana esters which are produced during the yeast growth phase.

Try this on your next batch - keep everything the same as the previous batch except aerate your wort. See if there is a difference and tell us about it.

As for aeration, wyeast did some work on the effectiveness of different aeration techniques. Taking out the option of a pure oxygen system, the best methods were:

aquarium pump with airstone for 5 minutes
shaking the wort container vigorously for 40 seconds

The surprising result was that these two methods gave equivalent dissolved oxygen in the wort. So the good news is if you haven't got an aquarium pump and airstone setup you can exert a bit of energy and get the same results.

edit: spell

Because yeast cells contain insufficient sterols and unsaturated fatty acids (UFAs), yeast growth only starts when appropriate levels of these essential
Membrane compounds are synthesized and the yeast cells use Oxygen to process these compounds, which then are used to prepare the cell wall for the uptake of wort sugars, so without adequate wort Oxygenation even if you pitched a bucket load of yeast in they will not be able to process the wort sugars because they will not be able to travel across the cell wall.

I just pitch 100000 cells/ml per 1 degree Plato, and Aerate the whole time Im transferring to the fermentor, which is usually about 30 mins, one thing I noticed since doing this is a much better attenuation, wheres before I was having problems getting down to the attenuation limit.

So as you can see Oxygen has many roles in fermentation, and for the cost of an aquarium pump $10, 5 micron S/S aeration stone $25, a sterile filler $5 and a bit of clear tubing for $5, its the little changes to your brewing practices like this that add up to better beer, and thats why we are here right.


Cheers

Brett :blink: