What does it mean to aerate?

[willbrown1020]

What does it mean to aerate? Does it mean to open the container or to stir? If it’s stir then how gently? I’m following a mead recipe and it calls for aeration

 

[Wrendelar]

Aerating your must means introducing oxygen when you are first mixing it and before you add your yeast.

The idea is to introduce oxygen into your must to help feed the yeast.

You can do this by shaking your container vigorously for a minute or stirring vigorously for a minute.

That’s the simple way to do it without having a way to inject pure oxygen into it

 

[MightyMosin]

The short story here is that higher oxygen aeration will develop a stronger yeast colony. Without proper aeration yeast are unable to control membrane fluidity through to the end of fermentation which leads to stuck fermentation and off-flavors.

Not having enough oxygen can create yeast that struggles and might produce some off flavors in addition to a higher ester production. A lack of dissolved oxygen can also lead to stuck fermentations.

Oxygen uptake by yeast is swift with the yeast deleting the oxygen in as little as 30 minutes of inoculation. To produce ethanol the yeast need to enter an anaerobic fermentation; they do this once there is low oxygen or high sugar levels. Oxygen is used to bud more daughter cells. If there is high enough glucose concentration, even without oxygen, the yeast will produce alcohol. It enters anaerobic fermentation.

Once your must is greater than 1.092 SG, using oxygen should be considered mandatory for proper yeast health; a must with a SG above 1.083 will benefit from additional oxygen somewhere between 12 to 18 hours after yeast pitch as this will increase fermentation speed and yeast attenuation. This second dose can speed fermentation by as much as 33%.

Aeration while using oxygen will provide an oxygen level in the must in the range of 8-10 PPM. Using a ½ micron stone will provide the desired oxygen levels.
Hand stirring the must will provide an oxygen level of ~4 PPM.
Aeration with a drill and wine degasser can provide an oxygen level approaching 8 PPM.
A filtered air pump with an aeration stone will provide ~8 PPM after ~60 minutes.
Flow Rate of O2 was 1L/minute

Method of Aeration for 5 gallons	Oxygen PPM
Shaking for 5 minutes	2.71 PPM
Pure 02 for 30 seconds	5.12 PPM
Pure O2 for 60 seconds	9.2 PPM
Pure O2 for 120 seconds	14.08 PPM

The above O2 numbers are with ½ micron aeration stone at 75F. This is from test data by White Labs.

 

[pauljHBOregon]

Another way to aerate is to simply pour your cooled wort into your fermentation vessel and then pitch your yeast (so be ready to pitch your yeast right after pouring into the fermenter). That's all I do any more, and yeast activity always starts on time. Pouring even my 5 gallon batches creates enough aeration (foam).

Hope it helps

 

[Jeroen79]

Its also ok to just siphon but let is splash in the middle instead of letting it in gently.

 

[k-daddy]

The short story here is that higher oxygen aeration will develop a stronger yeast colony. Without proper aeration yeast are unable to control membrane fluidity through to the end of fermentation which leads to stuck fermentation and off-flavors.

Not having enough oxygen can create yeast that struggles and might produce some off flavors in addition to a higher ester production. A lack of dissolved oxygen can also lead to stuck fermentations.

Oxygen uptake by yeast is swift with the yeast deleting the oxygen in as little as 30 minutes of inoculation. To produce ethanol the yeast need to enter an anaerobic fermentation; they do this once there is low oxygen or high sugar levels. Oxygen is used to bud more daughter cells. If there is high enough glucose concentration, even without oxygen, the yeast will produce alcohol. It enters anaerobic fermentation.

Once your must is greater than 1.092 SG, using oxygen should be considered mandatory for proper yeast health; a must with a SG above 1.083 will benefit from additional oxygen somewhere between 12 to 18 hours after yeast pitch as this will increase fermentation speed and yeast attenuation. This second dose can speed fermentation by as much as 33%.

Aeration while using oxygen will provide an oxygen level in the must in the range of 8-10 PPM. Using a ½ micron stone will provide the desired oxygen levels.
Hand stirring the must will provide an oxygen level of ~4 PPM.
Aeration with a drill and wine degasser can provide an oxygen level approaching 8 PPM.
A filtered air pump with an aeration stone will provide ~8 PPM after ~60 minutes.

Method of Aeration for 5 gallons	Oxygen PPM
Shaking for 5 minutes	2.71 PPM
Pure 02 for 30 seconds	5.12 PPM
Pure O2 for 60 seconds	9.2 PPM
Pure O2 for 120 seconds	14.08 PPM

The above O2 numbers are with ½ micron aeration stone at 75F. This is from test data by White Labs.

Missing from these guidelines is the o2 flow rate (LPM) to achieve those ppm's. Did White Labs publish that information?

 

[MightyMosin]

Missing from these guidelines is the o2 flow rate (LPM) to achieve those ppm's. Did White Labs publish that information?

They did.

It is 1L/Minute

I've edited the original post to include that information.

 

[willbrown1020]

Aerating your must means introducing oxygen when you are first mixing it and before you add your yeast.

The idea is to introduce oxygen into your must to help feed the yeast.

You can do this by shaking your container vigorously for a minute or stirring vigorously for a minute.

That’s the simple way to do it without having a way to inject pure oxygen into it

Ok but I was told that you should do it gently or it will turn the alcohol into vinegar? And to only do it for the first 2-3 days teice a day. And someone else is saying to use a wine drill but wouldn’t that be only usefull for right before adding the yeast in the first place?

 

[MightyMosin]

You want to really aerate before you pitch your yeast and again 12-18 hours after pitch depending on your original gravity. A mixer on a drill is really good for this.

Stirring twice a day is usually for degassing; that is, releasing suspended CO2 out of the must. You can use the mixer on a drill for this as well.

The key difference between aeration and degassing is how aggressively you are doing it and when. Degassing is done slowly as you are not trying to add O2 to the must but to release CO2.

As far as vinegar, that won't happen unless you get the right bacteria into your mead. Sanitize all your items that come into contact with your must.