Oxidation issues... Help!

[Jocky]

Has anyone experienced oxidation in their beer and found the cause?

I've had it in a couple of batches recently, along with acetaldehyde - something that occurs either because the beer isn't finished or post fermentation oxidation of ethanol... So I definitely seem to have a post fermentation issue.

This has been happening since a large number of changes in my brewing system. I thought at first it was a bottling issue, but I've been careful with that and can't see any splashing or air bubbles while transferring.

So the only thing I can see now is that I've been fermenting in a 25 litre bucket (that probably holds 27/28), but I've only been putting 15-16 litres in. I've also been leaving the lid cracked and not used an airlock. My normal primary is 2 weeks and then I bottle. The batches that are dry hopped don't seem to show it... as much, but I think it's still there.

So what do people think?

I'm thinking the next step will be to make a simple oxidation prone style (a bitter or porter) and ferment a smallish 11 litre batch in a 12.5 litre fermenter I have, with a blow off tube and then an airlock as soon as possible.

[Jim my]

What have you changed in your brewing process? Have you always chilled your wort or let it cool overnight?
The only reason I ask is that I recently read somewhere that oxidation can occur in your pre fermented wort between the temps of 80C and 26C ( has anyone else heard this?), i'll try and find where i read it.
I have to admit it confused me because I thought it was important to agitate your wort before pitching yeast, but not between those temps.....apparently.
I haven't brewed a decent beer yet but I hope to get to grips with it soon. Pretty sure I have Acetaldehide in my latest batch which is due to me underpitching yeast.

[Jocky]

Well, I changed my entire brewery and doubled my brew length.

I chill my wort - I get down to about 20-25C within 15 mins of boiling finishing using an immersion chiller. I guess there's some splashing then, but I also had it with a batch that went through a plate chiller.

[Jim my]

Found it



Oxidation
Tastes/Smells Like:
Stale or old, wet cardboard, sherry, papery, pineapple, decaying vegetables, Increased
bitterness, harshness
Possible Causes:
Oxidation occurs when oxygen negatively reacts with the molecules in the wort or beer.
An excessive level of oxygen being introduced to the beer, especially while wort is still
warm or after fermentation is complete, can create cardboard of sherry-like flavors.
Too much headspace in bottles can lead to oxidation as well. On the other hand,
aeration of wort before pitching yeast is necessary for yeast and good fermentation.
How to Avoid:
Oxidation is almost always a result of unnecessary splashing of fermented beer. When
transferring beer from one vessel to the next, prevent splashing by transferring beer
with tubing rather than pouring straight in. Keep the end of the transfer tubing
beneath the liquid line and avoid getting air pockets in the transfer tubing. Also, keep
exposure of wort to outside air at a minimum. Hot side aeration refers to wort becoming oxidized while it is hot. Warm liquid is
more inclined to absorb oxygen and therefore, it is recommended that when wort
is over 80ºF, splashing be avoided. During and directly after the boil splashing is not
much of a concern, as oxygen can’t really dissolve into liquid that hot. Cool wort as
quickly as possible and do not aerate wort until it is under 80ºF.
When bottling, only leave about ½” of headspace. The use of “oxygen absorbing”
bottle caps may help keep oxygen out of the bottle. When kegging, purge kegs with
Co2 to flush oxygen out of the headspace.

[Jim my]

Well, I changed my entire brewery and doubled my brew length.

I chill my wort - I get down to about 20-25C within 15 mins of boiling finishing using an immersion chiller. I guess there's some splashing then, but I also had it with a batch that went through a plate chiller.

It's not that then.

[BenB]

Changed to an Oxi cleaner and not rinsed properly? I'm wonder if my recent oxidation issues were partly caused by this....

[Eric]

If your beer contains yeast and fermentable ingredients it is highly unlikely to suffer oxidation. It does happen to old or filtered beers.

I do my damnedest to oxygenate wort for the yeast regardless of temperature. Most professional brewers and many amateurs inject pure oxygen.

I currently mostly use Yorkshire Square yeasts that need oxygen during fermentation. They climb high requiring no lid until the yeast head starts to collapse.

My beers never sit around once primary fermentation is complete, they are casked and primed so yeast deals with oxygen absorbed when spashed about during transfer.

It is possible your dry hopped beer has the same fault, just masked by those hops.

[Jocky]

Well my beer is neither old nor filtered - it's fermented and then bottle conditioned.

This article suggests that acetaldehyde presence indicates a post ferment oxidation issue (https://www.morebeer.com/articles/oxidation_in_beer), so it's either an issue from between fermentation and bottling or at bottling.

[Deebee]

Found it



Oxidation
Tastes/Smells Like:
Stale or old, wet cardboard, sherry, papery, pineapple, decaying vegetables, Increased
bitterness, harshness
Possible Causes:
Oxidation occurs when oxygen negatively reacts with the molecules in the wort or beer.
An excessive level of oxygen being introduced to the beer, especially while wort is still
warm or after fermentation is complete, can create cardboard of sherry-like flavors.
Too much headspace in bottles can lead to oxidation as well. On the other hand,
aeration of wort before pitching yeast is necessary for yeast and good fermentation.
How to Avoid:
Oxidation is almost always a result of unnecessary splashing of fermented beer. When
transferring beer from one vessel to the next, prevent splashing by transferring beer
with tubing rather than pouring straight in. Keep the end of the transfer tubing
beneath the liquid line and avoid getting air pockets in the transfer tubing. Also, keep
exposure of wort to outside air at a minimum. Hot side aeration refers to wort becoming oxidized while it is hot. Warm liquid is
more inclined to absorb oxygen and therefore, it is recommended that when wort
is over 80ºF, splashing be avoided. During and directly after the boil splashing is not
much of a concern, as oxygen can’t really dissolve into liquid that hot. Cool wort as
quickly as possible and do not aerate wort until it is under 80ºF.
When bottling, only leave about ½” of headspace. The use of “oxygen absorbing”
bottle caps may help keep oxygen out of the bottle. When kegging, purge kegs with
Co2 to flush oxygen out of the headspace.

Hot side aeration on the small batches we brew is almost a myth. Most people let their wort spash into a boiler. I was told this was a huge no no at the start, but have had no problems with it.
Boiling removes pretty much all of the oxygen from the wort and you need yo aerate it for proper yeast function.
I would lay my bet on the fermentation time against the amount of time you have the lid off.
Just my opinion though

[Jim my]

Hot side aeration on the small batches we brew is almost a myth. Most people let their wort spash into a boiler. I was told this was a huge no no at the start, but have had no problems with it.
Boiling removes pretty much all of the oxygen from the wort and you need yo aerate it for proper yeast function.
I would lay my bet on the fermentation time against the amount of time you have the lid off.
Just my opinion though

I have to admit I don't think I aerate enough, I just cool to about 23C in the boiler then let the wort splash into the fermenter and that's it. I have been having issues with fermentation and off flavours which I think are down to poor fermentation.
I saw a video on Youtube where someone was giving their wort a sound thrashing with a wine de gasser attached to a drill for a good few minutes and thought then that I'm not aerating enough.

[McMullan]

What Eric wrote, yeast buffer beer against oxidation. Most home brewers are probably worried about a myth.

Sounds like you've replaced your kit, Jocky. I’m wondering whether there’s a source of bacterial infection somewhere? What did the beer taste like prior to bottling? I’ve had an issue with new bottles in the past. Spores probably survived the ‘sterilisation' process. One possibility for acetaldehyde forming post bottling is the priming sugar feeding a bacterial infection.

Presumably you're using sufficient healthy yeast that fermented and attenuated without any noticeable issues? Same yeast in both batches? How many times have the yeast been reused, if they have? Reusing yeast too much can open the door to bacteria. Again, it becomes noticeable post bottling when they're fed by the priming sugar.

[TheSumOfAllBeers]

I have to admit I don't think I aerate enough, I just cool to about 23C in the boiler then let the wort splash into the fermenter and that's it. I have been having issues with fermentation and off flavours which I think are down to poor fermentation.
.

If you are pitching at 23C you are in the problem space for a lot of yeasts. Even for yeasts where ester and phenols are desirable, most Brewers pitch lower, say 17-18C and bring the temperature up gradually.

[Jocky]

So the possibilities are:
Cold side aeration (aka oxidation) Hot side aeration Infection Hot Side Aeration
While I mix vigorously while doughing in, the signs of HSA are sherry notes in the beer, and wouldn't be a cause of acetaldehyde. Evidence also suggests it's really hard to do on a homebrew scale - it's more on a commercial scale where you have thousands of gallons cascading 40 feet or problematic pumps.

Verdict: Quite unlikely.


Infection
A zymomonas infection can be a cause of acetaldehyde and I have had common equipment in these beers:
Buckets for fermenting and bottling; bottling tree; many of the bottles.
All my equipment is kept as clean as I can. Washing using PBW and sanitised in two stages, first with a soak in iodophor and then 30 seconds before contact with the wort/beer a squirt of starsan too.

Bottles are rinsed straight after use, drained, and then I add starsan and cap until next use.

I cool everything into a range of 20-25C within 20 minutes of flame out, and then chill in my brew fridge to 17-19C for pitching.

I've had this across multiple yeast batches. The yeast cake from an english porter that later showed signs of acetaldehyde in larger bottles (but not in smaller ones) was used for a strong porter which showed none of these problems and scored 35 in the national home brew competition. It may be that the stronger the flavours compliment or overwhelm any oxidation/acetaldehyde.

Verdict: Possible, but oxidation doesn't indicate infection.


Cold side aeration aka oxidation
So I've been dinged in a home brew competition for oxidation as well as acetaldehyde, and acetaldehyde is formed both in the fermentation process, but also by oxidation of ethanol.

Unlike the others I really can't see any reason to rule it out - while there have been some minor changes in my process, it's the one thing that has stayed fairly consistent across batches.

Verdict: Likely


Assuming it's oxidation, what are the possible causes?:
Short of purging my bottling bucket and bottles with CO2 I'm not seeing how I can make my bottling process any cleaner. Even then any oxygen uptake should be handled by yeast in the bottle.

That leads me to challenge my belief that airlocks/sealed fermentation are the devil's spawn and that they may have a use... or maybe that I've extrapolated that belief too far.

During active fermentation it's fine to use a massive open yorkshire square for any local dust/yeast/cats to fall into, but then I bet brewers that use a yorkshire square get it out of there as soon as it hits terminal gravity. As such my current practice of not sealing things up when fermentation drops off is possibly the (now seemingly idiotic) problem I've created for myself, even if everything is inside a temperature controlled fridge.

We shall see. In the mean time, any other anecdotes of how you've conquered oxidation/acetaldehyde are more than welcome.

[Jocky]

I have to admit I don't think I aerate enough, I just cool to about 23C in the boiler then let the wort splash into the fermenter and that's it. I have been having issues with fermentation and off flavours which I think are down to poor fermentation.
.

If you are pitching at 23C you are in the problem space for a lot of yeasts. Even for yeasts where ester and phenols are desirable, most Brewers pitch lower, say 17-18C and bring the temperature up gradually.

Sorry, I should say that I finish chilling to 17-19C in my brew fridge before I pitch. But I'll add it as a possible to my list.

[rpt]

I've done over 40 brews in a plastic bucket with a loose lid and no airlock. No oxidation problems. The only time I've had a problem was with beer left in a polypin for more than a month. Are your bottles glass or plastic?