How much O2 gets utilised during bottle conditioning?

[rossbaker]

I've been thinking about this for a while now and haven't found a consistent answer online. How much of the o2 in the headspace of a standard bottle of homebrew gets consumed during the bottle fermentation? All? Some?

 

[user 44743]

Some, definitely. It isn't only during the bottle fermentation either; the yeast are still alive and cleaning various things up afterwards.
But not all; in fact not all the oxygen in the head-space will even be absorbed into the beer.

 

[Grott]

The other day I opened a couple of bottles of 4 plus year old stout which had excellent carbonation and absolutely no adverse effects from oxygen. If you are bottling correctly (no bubbling down what ever you use to fill, then you’ll have no reason for concern.
Cheers

 

[n87]

I did some calculations here... and there is a concerning amount of O2 in the headspace: https://aussiehomebrewer.com/threads/how-much-o2-does-the-yeast-actually-consume-in-bottle.94479/

 

[Lyrebird_Cycles]

All of it.

Yeast will take up oxygen whenever they can. According to this paper, the oxygen consumption rate is of the order of 8 mg O2 / g yeast / hour. I add 250mg / l yeast to my bottle conditioned beers, that would take up the 5 mg/l expected oxygen in 2 1/2 hours.

BTW I deliberately add extra oxygen when mixing in the sugar and yeast.

I have an experiment in mind: I will bottle condition some beers in clear glass and do a methylene blue O2 test at intervals to see if actual rates correspond to the theory.

 

[MitchD]

What about when you transfer to a keg without priming sugar? If there is minimal head space will the oxygen present be enough to cause noticeable oxidation or is oxidation more likely to occur from poor transfer practices?

 

[Brewnicorn]

Can I ask a sub point, not wanting to derail the thread - Question in this thread there’s a point made about squeezing PET bottles to expel oxygen- any thoughts on whether this makes a difference here to flavour/longevity etc etc. bad and good would be interesting to know.

Dean’s query here -
Warning Regarding Big W PET Beer Bottles, and my Introduction to AHB

https://aussiehomebrewer.com/index....er-Bottles,-and-my-Introduction-to-AHB.91148/

 

[Bribie G]

What about when you transfer to a keg without priming sugar? If there is minimal head space will the oxygen present be enough to cause noticeable oxidation or is oxidation more likely to occur from poor transfer practices?

Both.
I've noticed an enormous difference in my keg beers since I started doing a low-oxygen transfer. I could go the whole hog and transfer through a post etc, but I just use a simple transfer method that exposes the beer to minimal oxygen and gets good results:

• Fill a keg right up to the lid opening with dilute starsan solution.
  
• Serve this through a kegerator tap until keg is empty
• Open the cornie lid a crack, enough to get the transfer hose down to the bottom
• The swirling and splashing will now be taking place in a CO2 atmosphere, not air as previously
• Any air that worked its way in when you opened the lid will be pushed back out as the beer level rises
• When filled, IMMEDIATELY withdraw hose, close lid and flush headspace for up to 30 seconds.

In my case it helps that the transfer hose is a skinny one as I use a SS conical, it's not the thick one that fits over a regular plastic tap so I just need to ease the lid open a tad.
I've noticed an amazing difference in freshness and preservation of hop flavour and aroma.

One way of keeping ahead of the game is, when you start this system, to always have your empty cornies full of CO2 and ready to go. So your first session you might have a couple or more cornies sitting around, so do the hard yards up front, flush them one after another. Then every time you blow a keg, get into the habit of washing and flushing right then before you put it away (also cleans the line and tap at the same time of course).

 

[TSMill]

All of it.

Yeast will take up oxygen whenever they can..

Whilst this is true, it does not implicitly follow that yeast uptake of available oxygen at this stage of fermentation is a good thing for your beer.

 

[MitchD]

Both.
I've noticed an enormous difference in my keg beers since I started doing a low-oxygen transfer. I could go the whole hog and transfer through a post etc, but I just use a simple transfer method that exposes the beer to minimal oxygen and gets good results:

• Fill a keg right up to the lid opening with dilute starsan solution.
  
• Serve this through a kegerator tap until keg is empty
• Open the cornie lid a crack, enough to get the transfer hose down to the bottom
• The swirling and splashing will now be taking place in a CO2 atmosphere, not air as previously
• Any air that worked its way in when you opened the lid will be pushed back out as the beer level rises
• When filled, IMMEDIATELY withdraw hose, close lid and flush headspace for up to 30 seconds.

In my case it helps that the transfer hose is a skinny one as I use a SS conical, it's not the thick one that fits over a regular plastic tap so I just need to ease the lid open a tad.
I've noticed an amazing difference in freshness and preservation of hop flavour and aroma.

One way of keeping ahead of the game is, when you start this system, to always have your empty cornies full of CO2 and ready to go. So your first session you might have a couple or more cornies sitting around, so do the hard yards up front, flush them one after another. Then every time you blow a keg, get into the habit of washing and flushing right then before you put it away (also cleans the line and tap at the same time of course).

I use one of these: https://www.brewhardware.com/product_p/fflbarb12.htm

Similar process to yours but straight down the out tube

 

[rossbaker]

I definitley go to great lengths to keep o2 out when transferring to a keg, and if I have a litre or 2 left over it usually goes into pet bottles so I can squeeze to remove the headspace. However, I've recently bottled a few litres with glass longnecks which has made me think more about this. It seems the traditional approach is to avoid aeration and splashing, but most home brewers seem to accept there will be a small amount of o2 in the headspace of a normal bottle which I keep thinking can't be a good thing. Yet it is common practise and seems to work well.

I've only recently realised some of the o2 might be utiIised by the yeast in the bottle. I would be keen to see some sort of data or experimental research if anyone can produce it.

Not thinking of anyone in particular... LC haha.

 

[Lyrebird_Cycles]

See post #5 in this thread.

 

[user 44743]

Another reference that may be of interest here

 

[peteru]

The Japanese study used pasteurised beer. Since they killed the yeast, it has no chance to consume the oxygen, therefore that study is irrelevant in this context.

 

[good4whatAlesU]

Was thinking about this the other day too in reference to how long to leave in primary before racking to a keg (before forced carbonation).

That is current wisdom appears to leave in Primary for up to 3 weeks to clean the beer up, however - preferably (I'm thinking) it's better to transfer into a keg earlier (10 days or so) while there is still a bit of yeast activity happening. That way the still active yeast will gobble up the 02 in the keg headspace and there will be less oxidation risk? Failing that you have to take precautionary action ; re; BribieG's earlier post.

Downfall of transferring early though .. is that there is a bit of yeast (cloudiness) on the bottom of the keg and picked up by the dip tube.

 

[user 44743]

The Japanese study used pasteurised beer. Since they killed the yeast, it has no chance to consume the oxygen, therefore that study is irrelevant in this context.

The paper obviously doesn't address the entire OP directly, but oxygen in the neck-space was one part of this. The reduction 'even' without yeast is of interest, and clearly the oxygen needs to reach the yeast before they can affect it. The study could even be considered to give an insight into part of the process without yeast confounding the variables. You may not agree, which is fine, but I don't accept that it is irrelevant.

 

[peteru]

Fair point. I was only looking at it from the yeast point of view. The paper provides insight into how oxygen gets into headspace and how even purging with CO2 can't prevent oxygen in the headspace due to it coming out of solution.

 

[gone brewing]

I recently did an experiment where I filled 6 brown PET bottles, squeezed the bottle before capping to leave no headspace in 3 of them and bottled the other 3 as usual, leaving some headspace. Firstly I did a blind tasting, then on another day drank one followed by the other then on another day tried them in the opposite order. I couldn't taste any difference between them. These were sampled about 4 weeks after bottling so maybe leaving the beer in the bottle for longer might make some difference, I didn't test that.

 

[good4whatAlesU]

The yeast will gobble up the oxygen if there's still a bit of meat on the bone. But if no sugar - then I suspect the O2 will oxidise the beer. Force carbed beers which have been fully fermented out prior to kegging/bottling are the ones that need to be handled with kid gloves.