Oxidation

[terrym]

I often read posts on this Forum where people are concerned about 'oxidation'.
This covers anything from opening the FV lid during the primary to take a peek inside to transferring the brew from one container to another, say FV to bottles.
I have to say that I have never noticed any effect of 'oxidation' on any of the large number of brews I have done over the years. I make sure that I don't unnecessarily introduce any air directly into the brew after the initial thrash before I pitch the yeast, but am not paranoid about it. I transfer into a second FV at the end of the primary by siphon, I sometimes have to rouse the yeast by stirring if it has stuck or the yeast is heavily top fermenting (viz. 1698 yeast) but try not to introduce air, I don't use a bottling wand, and I use 2 litre bottles and can keep beer in a bottle after opening for a few days without it spoiling.
And I do know what oxidized beer tastes like, I have tasted a few in pubs over the years.
So I wondered whether 'oxidation' is almost an old wives tale among home brewers without much foundation, unless you do something really silly.
What do others think?

 

[MyQul]

I've had oxidised beer when using coopers pet bottles, so switched to glass. I've mentioned this before and loads of people replied "I've never had problems with coopers bottles". Not sure why it happened. Wether I didn't tigheten the lids properly (although the beer was carbed up fine), the oxi-barring layer somehow 'wore out' or perhaps something else. I'm not sure really.

I think oxidation is also something that happens over time. I was as London Brew Lab where they do beer making courses/lessons/days and where I used to buy my ingredients. One day, whilst wait for my order to be made up I was watching what was going on as usual and some customers who had made a beer a few weeks earlier had come in to bottle. I watched in absolute amazement as the two guys that run/own the place lifted up a FV and simply poured it into a bottling bucket. There was masses of foam of course. I asked the guy about oxidising the beer and he said he'd never tasted oxidisation in any of the HB's they make and it was all a matter of time as it takes quite a long time for oxidisation to spoil a beer and the HB his customers made is usually consumed before any oxidisation occcurs

 

[Covrich]

I have never had it but a lot of people have.. I think if you're careful opening the FV lid you won't cause any oxidation.. good siphoning technique you should be okay..

My worry about racking to a secondary just after week one is that if you leave it in the FV it will drop out anyway with a cloud of co2, if you leave it to do practically the same job in the secondary you leave it exposed with most likely much less protection above it.. Good solid racking into a bottling bucket from a primary thats been sat mitigates the advantage imo, unless I was looking to bulk age and would want it off the trub.

That is just my take on it.. if you're careful with your trasnfers you should be okay, but every transfer adds an opportunity for it I guess...

 

[Cwrw666]

I've never had any oxidation issues. And that includes transferring to Pressure barrel by simply opening the FV tap and letting it blast down into the barrel. Same when bottling - open tap, blast the beer into a froth filling a jug then filling bottles via a funnel.
Mind you I've never oxygenated my beer wort before pitching the yeast either - a thoroughly pointless activity as far as I'm concerned.

Can anyone explain please why you must avoid oxygen at all costs with beer, but on this forum, when people are wine making, at the end of fermentation they `de-gas' their wine by whizzing it into a froth. If you recomended doing this with beer people would have a hissy fit!:lol:

 

[terrym]

I have never had it but a lot of people have..

Maybe you have identified the problem if one exists.
People have no personal experience of oxidation, but believe others have.
So what we need, is to hear from those 'others' who have had an oxidized brew and tell why it happened so that we can all base our own techniques for oxidation avoidance on evidence, rather than simply believing what could happen, whether realistic or not.
Other than that I have to say that, for me, opening an FV lid during the primary of an ordinary brew is most unlikely to oxidize the contents. For example many traditional commercial brewers still use open fermenters, like their predecessors, and they are clearly not concerned about oxidation.

 

[MyQul]

Can anyone explain please why you must avoid oxygen at all costs with beer, but on this forum, when people are wine making, at the end of fermentation they `de-gas' their wine by whizzing it into a froth. If you recomended doing this with beer people would have a hissy fit!:lol:

On a similar point to this, mini keg are recommened to be drunk in about 3 days, I think because oxygen is supposed to spoil the beer any time after that. I normally drink one over 4-5 days and dont notice any difference from day one. I opened a MK last night. I might try and make it last 7 days (I know, a BIG ask :lol:) to see what happensif there's any big difference in taste. I normally close the bung vent after every pour, which I think helps a lot

Very interesting thread this.

 

[Sarenth]

This is taken out of the IBD GCB revision notes.

 

[Covrich]

I always thought oxidation is not supposed to be immediate just more a case of long term shelf life.. I think its something like wrapping food up or leaving it in the fridge open it can go off quicker with the exposure. ( I could be talking rubbish there!!)

If you drink a batch in a few weeks even if you supposedly "oxidised" I doubt you'd ever run into issues

 

[DoctorMick]

I don't have the right size tube to connect to the tap on my fermenter so when I transferred to my bottling bucket I just ran it from the FV down the side of the bucket but I could see there was quite a bit of splashing. I'll be interested to see if/how big a problem it causes.

 

[Brew_DD2]

On a similar point to this, mini keg are recommened to be drunk in about 3 days, I think because oxygen is supposed to spoil the beer any time after that. I normally drink one over 4-5 days and dont notice any difference from day one. I opened a MK last night. I might try and make it last 7 days (I know, a BIG ask :lol:) to see what happensif there's any big difference in taste. I normally close the bung vent after every pour, which I think helps a lot

Very interesting thread this.

Exactly the same for me. I've had some beer a week after I opened my easy keg. A little flat but still fresh. I'd imagine the blanket of CO2 continues to protect the beer when you close the vent bung.

 

[MyQul]

Exactly the same for me. I've had some beer a week after I opened my easy keg. A little flat but still fresh. I'd imagine the blanket of CO2 continues to protect the beer when you close the vent bung.

Flat, yes (which I dont mind) but I agree still fresh. I imagine what's happening, as there's problably quite a lot of yeast at the bottom of a MK it continues to create a blanket of C02 even after several days, as long as you close the bung vent

 

[IainM]

I've always taken care to avoid it, so wouldn't be able to recognise it, but surely someone here must have noticed the 'off' taste that people talk about a few days after a pressure barrel start glugging.

 

[DarrenSL]

I think it's logical to assume that oxygen exposure will be detrimental to beer. However, for most, the oxygen is introduced at bottling so the amount of oxygen absorbed plus the storage temperature and time to drink means that most won't notice any off flavours.

I'm working in a theory at the moment. I've had a few problems recently which I noticed were mainly affecting heavily hopped beers. I have also been pitching yeast too high at c.30C which I know is a big no no but was due to my fear of infection and trying to get the yeast in asap and checking the temperature by touch only. I think the real problem with high temperature pitching isn't so much the yeast health but oxygenation, particularly of hop components. At this temperature oxygen solubility is high and oxidation reactions are faster.

My off flavour starts off after 3 weeks with a sherry like aroma but deteriorates over then next few weeks to a rotting veg smell. Fortunately I can recognise the deterioration early so just drink the beer quicker! :-)

Im experimenting at the moment with a side by side fermentation, one pitched high the other low. I'll let you know how it goes.

 

[HebridesRob]

I think it's logical to assume that oxygen exposure will be detrimental to beer. However, for most, the oxygen is introduced at bottling so the amount of oxygen absorbed plus the storage temperature and time to drink means that most won't notice any off flavours.

I'm working in a theory at the moment. I've had a few problems recently which I noticed were mainly affecting heavily hopped beers. I have also been pitching yeast too high at c.30C which I know is a big no no but was due to my fear of infection and trying to get the yeast in asap and checking the temperature by touch only. I think the real problem with high temperature pitching isn't so much the yeast health but oxygenation, particularly of hop components. At this temperature oxygen solubility is high and oxidation reactions are faster.

My off flavour starts off after 3 weeks with a sherry like aroma but deteriorates over then next few weeks to a rotting veg smell. Fortunately I can recognise the deterioration early so just drink the beer quicker! :-)

Im experimenting at the moment with a side by side fermentation, one pitched high the other low. I'll let you know how it goes.

Hmm not sure what you mean. Are you saying you aerated the wort while it was still warm and then pitched the yeast? If you didn't aerate I don't see why there would be any more oxygen.
Yeast is supposed to use up oxygen pretty fast. Oxidation reactions would need to be very fast to cause issues before the yeast had a chance to take the oxygen out of solution.
Interesting though, for sure.

 

[DarrenSL]

Sorry, yes I had been aerating (with pure O2) at around 30C then pitching yeast (which refers to the OPs point "..unless you do something really silly"!)

There are lots of articles and forum discussions around the world regarding 'hot side aeration' with many considering this to be a myth. However in the significant majority of cases they are commenting on aeration of the mash and oxidation of malt.

My current thinking is:
-Oxygen is twice as soluble at 30C as it is at mash temperatures.
-If splashing mash is a concern then I expect forcibly aerating wort is much more likely to cause oxidation (particularly with pure O2)
-As well as malt there are hops present that can also be oxidised.

It's not a new idea that hot wort shouldn't be splashed around or aerated, it's actually mentioned in John Palmer's book. The widely accepted rule is to aerate below 25C but I'm struggling to find much on the subject other than 'don't do it'.

 

[HebridesRob]

Sorry, yes I had been aerating (with pure O2) at around 30C then pitching yeast (which refers to the OPs point "..unless you do something really silly"!)

There are lots of articles and forum discussions around the world regarding 'hot side aeration' with many considering this to be a myth. However in the significant majority of cases they are commenting on aeration of the mash and oxidation of malt.

My current thinking is:
-Oxygen is twice as soluble at 30C as it is at mash temperatures.
-If splashing mash is a concern then I expect forcibly aerating wort is much more likely to cause oxidation (particularly with pure O2)
-As well as malt there are hops present that can also be oxidised.

It's not a new idea that hot wort shouldn't be splashed around or aerated, it's actually mentioned in John Palmer's book. The widely accepted rule is to aerate below 25C but I'm struggling to find much on the subject other than 'don't do it'.

Certainly, a convincing hypothesis. I can see how introducing a lot of oxygen at 30-40c might lead to reactions with substances in the beer.
Many people are careless about oxidation at the mash stage (think sparge arms) I don't think the problem can be that bad at that stage or there would be a lot of people with horrible beer. I do try to avoid splashing at all points but I can't help it at the point of transferring the sweet wort to the boiler with my current equipment. I haven't noticed anything.