Where does the possibility of oxidation come from?

[Buffers brewery]

A little bit at odds with @JockyBrewer Xbeeriment as I switched from glass to PET bottles as I considered the process of filling a PET bottle to the top with a wand and then loosely fitting the cap before squeezing the bottle to expel the air and a little drop of beer and then screwing the cap down tight leaving the bottle squidged (technical term) until carbonation re-inflated the bottle the best way to avoid oxidation. WOW! That’s a long sentence

 

[JockyBrewer]

A little bit at odds with @JockyBrewer Xbeeriment as I switched from glass to PET bottles as I considered the process of filling a PET bottle to the top with a wand and then loosely fitting the cap before squeezing the bottle to expel the air and a little drop of beer and then screwing the cap down tight leaving the bottle squidged (technical term) until carbonation re-inflated the bottle the best way to avoid oxidation. WOW! That’s a long sentence

I can see that working well.

I’m certain the problem is not that the PET bottles or caps are porous, but the oxygen left in the headspace is absorbed better by the crown cap liner than whatever the Coopers PET bottle cap liner is.

 

[foxy]

I can see that working well.

I’m certain the problem is not that the PET bottles or caps are porous, but the oxygen left in the headspace is absorbed better by the crown cap liner than whatever the Coopers PET bottle cap liner is.

You should read Ken Grossman's article about oxygen scavenging liners.

 

[matt76]

You should read Ken Grossman's article about oxygen scavenging liners.

Do you have a link? Google isn't readily revealing such an article.

 

[matt76]

Sorry a wee bit slow on the replies today - busy day picking my son up from University.

Ok the ascorbic acid is an oxygen scavenger - or to be picky - it scavengers oxygen free radicals which isn't quite the same as dissolved oxygen but is the active oxygen that causes oxidation. Ascorbic acid isn't stable to heat so there's no point adding while the wort's boiling.

I add vit C at the dry hop stage, and it doesn't matter if you are dry hopping at high krausen, the process of dry hopping will inevitably introduce oxygen unless using pellets in a bag which was introduced at the start of the ferment (the magnet release method). Cold crash doesn't have to introduce oxygen if you use a balloon filled with CO2 - How to: Balloon CO2 collection (Bruloonlock)

The experiments on the amount of air in a bottle are v interesting, essentially cap on foam seems to be the key part. If you've cold crashed and carbonated before bottling then it's a bit easier, more problematic if bottle conditioning. I'm not sure about the bicarb method, I suspect the amount of bicarb needed to generate enough CO2 would also alter the flavour.

I've had vague wonderings about how it might be possible to fill the bottles in a covered environment so that removing the filler sucks CO2 back rather than air. At the moment when I withdraw the filler I have been squirting CO2 in the neck which causes enough turbulance in the liquid to generate foam to cap on.

Anna

@DocAnna thanks for this. I forget the refuse amounts you said you add, but are you saying that the vitC you add at dry hop is still active and beneficial at bottling?

Or are you saying you still need to deal with air in the headspace of bottles by calling on foam etc?

 

[foxy]

Do you have a link? Google isn't readily revealing such an article.

I did have I will have a look later, Sierra Nevada Brewing tried them for a while but found them no better than the standard caps. He ended up saying they were still looking for the Holy Grail of caps.

 

[DocAnna]

@DocAnna thanks for this. I forget the refuse amounts you said you add, but are you saying that the vitC you add at dry hop is still active and beneficial at bottling?

Or are you saying you still need to deal with air in the headspace of bottles by calling on foam etc?

Ah good questions! The amount of oxygen free radicals the vit C absorbs is pretty variable based on the previous posts, and the calculations were extremely conservative so yes I'd expect the vit C still to be active at bottling. However, I still think it's worthwhile capping on foam since the vit C is a back up rather than anything else. One of the things I would like to test out once I've finished the current NEIPA (which oddly enough I'm not using vit C in - long story) is to do an experiment with samples left open to the air, with a proportionate amount of vit C added. I am hoping that will illustrate whether it slows/avoids oxidation at that late stage or not.

Anna

 

[JockyBrewer]

I did have I will have a look later, Sierra Nevada Brewing tried them for a while but found them no better than the standard caps. He ended up saying they were still looking for the Holy Grail of caps.

I'd be interested in reading that too.

Perhaps for Sierra Nevada they're no better, but I'm going to guess that Ken isn't filling and capping all their beers by hand, and instead have a system that manages to fill and cap bottles with oxygen in the parts per billion. Not to mention the expensive measurement equipment to check that level.

I know the oxygen scavenging caps work for me - what I've posted earlier on this thread is just the latest in a number of experiments I've done. For example, earlier in my brewing career I had a hoppy pale lager which went half into swing tops and half into crown cap bottles. The beer in the swing tops came out a different colour to the crown caps. Obviously that says as much about my terrible bottling technique at the time as the the crown caps, but it made me realise that they did have an effect.

 

[matt76]

Breweries have been bottling for years without any problem it is only now when shipping is out of the breweries hands it becomes a problem.

Perhaps for Sierra Nevada they're no better, but I'm going to guess that Ken isn't filling and capping all their beers by hand, and instead have a system that manages to fill and cap bottles with oxygen in the parts per billion.

A couple of thoughts - and this is just idle conjecture...

@foxy is undoubtedly correct. But I would counter this by suggesting the overwhelming majority of commercial bottled beer is force carbonated, and already carbonated at bottling.

I'll also suggest that the majority of these even today are not hoppy beers that are going to be so sensitive to oxidation.

And as @JockyBrewer days, homebrewers generally don't have access to commercial bottling equipment.

I can't speak for homebrewers who keg and/or bottle carbonated beer from kegs.

But I don't - all my beer is bottle conditioned and I have no interest in kegging. And for my not-so-hoppy beers (pale lagers, porters, stouts) I have no problem.

I do wonder if the problem is somehow specific to bottle conditioning, and if so, why would that be...

But I can say for sure that as I become more discerning and self-critical I can tell a difference in hoppiness in my hoppy beers (=> hop fade) at just 1 and 2 weeks after bottling.

(N.B. 1 week seems not quite long enough for the beer to fully carbonate - it's drinkable at this point but really needs 2 weeks to carbonate properly).

I'm not talking mega oxidation - I'm not seeing marked colour change or soggy cardboard flavours. But there is a noticeable reduction in intensity of hop aroma and flavour. Which is irritating

It seems sensible to me to at least try some simple measures to further reduce oxygen exposure, if only to rule it out as a cause.

And if it's not caused by oxygen exposure then what is it!

 

[JockyBrewer]

I can't speak for homebrewers who keg and/or bottle carbonated beer from kegs.

But I don't - all my beer is bottle conditioned and I have no interest in kegging. And for my not-so-hoppy beers (pale lagers, porters, stouts) I have no problem.

I do wonder if the problem is somehow specific to bottle conditioning, and if so, why would that be...

When bottle conditioning you're usually leaving air in the headspace, whereas bottling from an already carbonated keg you'll tend to have foam (CO2 bubbles) filling the void.

When I went from bottle conditioning to kegging my hoppy beers improved instantly. Night and day different.

If I went back to bottle conditioning I'd probably reduce the headspace quite a bit and try to produce some CO2 based foam while bottling to purge the headspace.

 

[dad_of_jon]

Following @Clints tip when I remove the bottling wand I reduce the headspace by holding the bottle at an angle and pressing the wand at the side of the neck. no spillage and it works for me.

 

[foxy]

A couple of thoughts - and this is just idle conjecture...

@foxy is undoubtedly correct. But I would counter this by suggesting the overwhelming majority of commercial bottled beer is force carbonated, and already carbonated at bottling.

I'll also suggest that the majority of these even today are not hoppy beers that are going to be so sensitive to oxidation.

And as @JockyBrewer days, homebrewers generally don't have access to commercial bottling equipment.

I can't speak for homebrewers who keg and/or bottle carbonated beer from kegs.

But I don't - all my beer is bottle conditioned and I have no interest in kegging. And for my not-so-hoppy beers (pale lagers, porters, stouts) I have no problem.

I do wonder if the problem is somehow specific to bottle conditioning, and if so, why would that be...

But I can say for sure that as I become more discerning and self-critical I can tell a difference in hoppiness in my hoppy beers (=> hop fade) at just 1 and 2 weeks after bottling.

(N.B. 1 week seems not quite long enough for the beer to fully carbonate - it's drinkable at this point but really needs 2 weeks to carbonate properly).

I'm not talking mega oxidation - I'm not seeing marked colour change or soggy cardboard flavours. But there is a noticeable reduction in intensity of hop aroma and flavour. Which is irritating

It seems sensible to me to at least try some simple measures to further reduce oxygen exposure, if only to rule it out as a cause.

And if it's not caused by oxygen exposure then what is it!

It isn't a problem for home brewers, everyone has I different technique I have also bottled with a bottling wand and filled it just about to the top but don't bother now.The bottles don't get shaken about, just carried into the fermenting room or the cask and bottle storage area during the winter and I don;t leave them hanging around for an age.
When I went on the tour of Brooklyn Brewery they partially carbonate their beer by capping the fermenter, it is then carbonated to the level they want on the bottling line. I did ask how they knew how much co2 to put in but that was the one question the guide couldn't answer. The bottles are hit with a jet of water making the diluted co2 foam and the bottles capped.
If anyone is getting oxidised beer then I would be looking elsewhere, for that air in the head space to dissolve into the beer I have found takes about 2 years, unless it is getting moved from pillar to post shaken up and kept at too higher temperature.

 

[The-Engineer-That-Brews]

I have read that using sodium metabisulphate (e.g. Camden tablets) is more effective at removing oxygen than purging kegs and bottles etc.

e.g. this brülosophy exBeeriment

 

[JockyBrewer]

Be careful with sodium metabisulphite. I added 0.2g to a batch before bottling and it ended up very sulphury.

 

[foxy]

I have read that using sodium metabisulphate (e.g. Camden tablets) is more effective at removing oxygen than purging kegs and bottles etc.

e.g. this brülosophy exBeeriment

Here is a good place to start for those who worry about oxidised beer.
https://www.themodernbrewhouse.com/

 

[JockyBrewer]

If anyone is getting oxidised beer then I would be looking elsewhere, for that air in the head space to dissolve into the beer I have found takes about 2 years, unless it is getting moved from pillar to post shaken up and kept at too higher temperature.

How are you measuring the dissolved oxygen over time?

If there’s a higher concentration of oxygen in the headspace then there is in the beer, it will dissolve into the beer over days or hours while under pressure.

 

[DocAnna]

How are you measuring the dissolved oxygen over time?

If there’s a higher concentration of oxygen in the headspace then there is in the beer, it will dissolve into the beer over days or hours while under pressure.

If anyone really would like to read about the dynamics of oxidation and in particular at bottling then I recommend this as a good read - which I've referenced previously [PDF] A New Approach to the Kinetics of Beer Oxidation: From Physical Chemistry to Industrial Brewing | Semantic Scholar
This details how oxygen appears to enter solution within minutes of bottling from the headspace though their summary does say this would not be the case if the foam slow down oxygen diffusion.
Having continued to read around this subject, there's a really depressing review of the effect of oxidation here, but sadly it's not public access for the paper (but you can access it through a university online library if you have links to one)
Kuchel, Lynne, Brody, Aaron L & Wicker, Louise, 2006. Oxygen and its reactions in beer. Packaging technology & science, 19(1), pp.25–32.
This sets out all the measures that industry have taken to eliminate oxygen but still find degredation even at tiny amounts of oxygen - 50 parts per billion which is where commercial oxygen minimising was in 2005 - there's still progressive oxidation, which is also temperature dependent.

So the overall message is we should do our best to minimise oxygen contact but not beat ourselves up about it since even with all the best tech in the world, we can't completely avoid oxidation. Oh and don't store beer warm as it will degrade quickly whatever you do - 30 deg in one paper and 40 deg in another was tried and it oxidised whatever the level of oxygen.

Anna

 

[foxy]

How are you measuring the dissolved oxygen over time?

If there’s a higher concentration of oxygen in the headspace then there is in the beer, it will dissolve into the beer over days or hours while under pressure.

But it doesn't disolve in hours or days it is months or years dependent on how the beer is stored. Stop looking at it from a commercial brewers point of view and look at it from a home brewers perspective. Charlie Bamforth has a good pod cast on oxidation. Look it up.

 

[531Man]

- Oh and don't store beer warm as it will degrade quickly whatever you do, 30 deg in one paper and 40 deg in another was tried and it oxidised whatever the level of oxygen.
Anna

I hope you don't mind this interjection in this technically detailed and interesting discussion.
To make it clear for our USA (Fahrenheit users) and older Brit. members I believe you mean degrade quickly at 30°C and 40°C, here.

As an aside, I did even hear the American Chief immunologist Anthony Fauci speaking about storage of Covid vaccines on BBC R4 and even he sloppily said minus 100 degrees, (omitting the Fahrenheit) whereas we would say store at the more familiar to us, of minus 70°C.

 

[DocAnna]

I hope you don't mind this interjection in this technically detailed and interesting discussion.
To make it clear for our USA (Fahrenheit users) and older Brit. members I believe you mean degrade quickly at 30°C and 40°C, here.

As an aside, I did even hear the American Chief immunologist Anthony Fauci speaking about storage of Covid vaccines on BBC R4 and even he sloppily said minus 100 degrees, (omitting the Fahrenheit) whereas we would say store at the more familiar to us, of minus 70°C.

Oh quite right, and apologies, yes 30 and 40 deg C, ie v warm and too hot. Why the US still uses Fahrenheit is genuinely beyond me sorry , not meaning to be personal but it is a bit odd as scales go.