The O2 arena

[SilverShadow]

Hey guys,

Another quick post to gather your thoughts and invaluable advice

This time it's about exposure of beer to oxygen....

Many a brew video shows some brewers absolutely scathing of any exposure to oxygen whatsoever, allowing their brew less air than anaerobic bacteria to get in. Others seem to be fairly relaxed about the whole thing, almost blasé

So, I thought I'd ask the audience..

1) Do you find even a couple of mins would alter the quality of your brew, or are we talking hours/days worth of exposure to really impact it?

2) Presumably subsequent purging with CO2 will minimise any brief exposure?

3) Are certain beers more susceptible (eg, hoppy pale, porter, lager, etc)?

4) Is there a point in the fermentation & kegging process where it's effect are more/less significant?

5) Any other thoughts / recommendations?


For the record, I briefly open my FV lid to dry hop halfway, but don't have any way (yet) to purge afterwards. Transferral to keg takes a few moments via a pipe directly into the keg, which is then purged with CO2. But it does have 5-10 mins exposure while transferral occurs.

I'm just wondering if those brief moments are giving significant problems to the final product

Thanks for your expertise

 

[foxy]

For the home brewer it is nowhere as important as it is for the commercials. Comes down to logic, many years ago there were breweries all over the country mainly supplying locals. They weren't shipping beer all over the country or the world, beer was drunk fresh and kept cellared. Keep your beer cool and drink fresh and there will not be a problem. I think the heavy hopped beers are the biggest problem whenever I read about oxidised beers it is usually the NEIPA's, don't hear much about most others.

 

[SilverShadow]

Cheers Foxy

Many of my beers are of the hoppy / IPA genre, so probably more sensitive to this. However, it only gets brief exposure to O2 before being enclosed again, and i've usually drank within 2-3 weeks (after conditioning in a keg for a fortnight)

On a separate thread, i saw a discussion about ways to dry hop without oxygen exposure. I saw one video of a guy with a neat bespoke invention - surprised him or nobody else has developed a budget product to dry hop inside the FV

 

[nickjdavis]

Cheers Foxy

. I saw one video of a guy with a neat bespoke invention - surprised him or nobody else has developed a budget product to dry hop inside the FV

They have...its called a magnet. Pop your dry hop hops inside a muslin bag with a weight inside and a magnet. Attach said bag to the underside of the lid of your FV by means of a magnet on the outside. Put lid on FV and let the fermentation do its thing...when ready to dry hop just remove the external magnet and the bag will drop into your fermented beer. Solutions don't need to be complicated.

The problem with brewing is that there are a vast number of folks out there who have agendas, who effectively raise alarms about certain aspects of brewing and convince the world that they will brew bad beers if they dont do X, Y and Z....but then produce product to alleviate such issues and sell them by the bucket load because folks are scared that they're going to ruin their batch.

The world of "exposure to O2" is one such area. Dont get me wrong....post fermentation Oxygenation of your beer is something to be avoided and hoppy styles (and as mentioned...this does seem to have rocketed along with the popularity of NEIPA's) are indeed far more susceptible to the affects of O2. But when folks are scared to take the lid off their fermenter to add some dry hops or maybe to take a gravity reading....you know things have gone too far.

A few seconds exposure to air for the vast majority of brewers/brews/styles is not going to suddenly oxidise your beer....no you don't want to be wildly splashing around with a spoon trying to rouse yeast, or you don't want to be splashing the beer greatly as you go through your bottling or other packaging process....but as long as you are sensible and minimise the time your FV is open then you are unlikely to suffer the issues the world would have you believe you are going to experience.

For the record, I briefly open my FV lid to dry hop halfway, but don't have any way (yet) to purge afterwards. Transferral to keg takes a few moments via a pipe directly into the keg, which is then purged with CO2. But it does have 5-10 mins exposure while transferral occurs.

Why don't you purge the keg first?

 

[Northern_Brewer]

1) Do you find even a couple of mins would alter the quality of your brew, or are we talking hours/days worth of exposure to really impact it?

Discussion of this kind of stuff is complicated by the fact that really you're talking about two separate things - exposing malt flavours to oxygen where you're mostly worrying about the boil, and exposing hop flavours to oxygen which is more about dry hopping on the cold side.

And worrying about oxygen can seem a bit "foreign" to British brewers as British beers are typically served on cask where some oxygen ingress is part of the style. But that's not to say it's not useful to see how others do things to see if you can't improve your beers.

It's a basic principle of chemistry that chemical reactions happen faster at higher temperatures, it's in the ballpark of doubling in speed with every 10°C increase in temperature. So reactions at 100°C might happen at 256x the speed of reactions at 20°C - or in other words 1 minute in the boil is the equivalent of >4 hours at room temperature. That's why people worry about hot-side oxidation, the oxidation/"staling" reactions can happen within minutes when wort is exposed to oxygen in the boil. So the "LODO" gang have historically worried about oxygen getting to malt in the boil, to preserve the malt flavours in styles where malt is to the forefront, like lagers, but were (relatively) less worried about oxygen on the cold side.

That changes once you start dry hopping to the massive extent seen in eg NEIPAs, as the compounds released in dry hopping are more sensitive to oxygen, so will oxidise even at low temperatures. So that's where closed transfers etc come in, and by all accounts they help a lot - as long as you do them properly! And with NEIPAs you get pretty quick feedback if you're getting oxidation, as your beer turns to murky brown rather than a bright orangey-yellow.

So it depends on whether you're making things like lagers, where you're worried about hot-side oxidation of your malt, hazies where you're worried about cold-side oxidation of your dry hops, or British beers where oxidation is a feature and not a problem (ish). Having said that, I think it will never hurt to protect your beer at all stages from oxygen where possible - it's easy to add oxygen at a later stage - and even for British beers I will take some basic precautions on the hot side, like pre-boiling my water before the mash, and adding half a Camden as I do so.

 

[Braufather]

It's a basic principle of chemistry that chemical reactions happen faster at higher temperatures, it's in the ballpark of doubling in speed with every 10°C increase in temperature. So reactions at 100°C might happen at 256x the speed of reactions at 20°C - or in other words 1 minute in the boil is the equivalent of >4 hours at room temperature.

Ive always worried about mashing in the braumeister, as part of the design the wort pumps up through the malt pipe and splashes down the outside, so there must be a lot of oxygen ingress at 65 and 78c over 70-90 mins? previously ive thought it good to help the yeast later, but since all the Low O2 talk ive worried a bit about it. You can get a conversion kit for a full volume mash to eliminate this and ive considered it but still not sure if its needed.

 

[Northern_Brewer]

previously ive thought it good to help the yeast later

It's irrelevant to the yeast, as the act of boiling effectively drives out all the dissolved oxygen and "resets" the oxygen content.

I don't know the Braumeister but that doesn't sound ideal, at least for malt flavours in malt-led beers.

 

[Braufather]

cheers, im going to dig deeper!

 

[foxy]

Ive always worried about mashing in the braumeister, as part of the design the wort pumps up through the malt pipe and splashes down the outside, so there must be a lot of oxygen ingress at 65 and 78c over 70-90 mins? previously ive thought it good to help the yeast later, but since all the Low O2 talk ive worried a bit about it. You can get a conversion kit for a full volume mash to eliminate this and ive considered it but still not sure if its needed.

Charlie Bamforth covers HSA in one of his podcast, he mentions that Coors I think it was recirculate the wort and it is splashing away on the return. As far as HSA and home brewers goes he does say it isn't a problem.

 

[RichardM]

Ive always worried about mashing in the braumeister, as part of the design the wort pumps up through the malt pipe and splashes down the outside, so there must be a lot of oxygen ingress at 65 and 78c over 70-90 mins? previously ive thought it good to help the yeast later, but since all the Low O2 talk ive worried a bit about it. You can get a conversion kit for a full volume mash to eliminate this and ive considered it but still not sure if its needed.

It really isn't splashing to any extent. It flows over the top of the malt pipe and then runs down the side.

 

[chthon]

As someone who tries to get a good product with the minimum necessary tools, I haven't found any problems.

• I mash in a 10l stock pot. Mix and stir carefully.
• I manually move my mash to my filter tun. Don't drop it, but pour it gently along the side of the filter tun.
• I recirculate.
  • Always make sure that the output of the tube is at the bottom of the receptacle and make sure that it is covered quickly in wort.
  • I pour carefully back on a plastic lid (Tupperware) which floats on top of the wort of my mash tun
• When filtering, I try to get a slow consistent feed into my boil kettle, with the output of the filter tube covered as much as possible in the wort
• After boiling, I cover my boil kettle with a temperature resilient plastic bag. I let it cool overnight, and the plastic bag keeps air out.
• I open ferment from my boil kettle for five days, then rack into a closed vessel. I always keep some sugar or wort from the boil or filtering so that fermentation keeps on going. Oh, and currently I always try to brew 10l, which minimises my head space for my glass fermenters.
• I bottle from bottle pail, so this is a second racking. Stir gently sugar and bottling yeast.

I have always been able to keep up my beers, even very light coloured ones, for up to a year without darkening. A year, because I do want them to be drank by then.
I don't care for NEIPA, but I like to use extra hops, at the end of the boil or during a hop stand. Even these keep nice in colour. And I use both crown caps and swing top bottles.

 

[Braufather]

It really isn't splashing to any extent. It flows over the top of the malt pipe and then runs down the side.

mine has the occasional tendency to channel along the lift posts and drop from there.

 

[Binkei Huckaback]

Oh. I thought this was going to be a thread about the Millennium Dome. How disappointing.

 

[stripeyjoe]

Oh. I thought this was going to be a thread about the Millennium Dome. How disappointing.

And their massively overpriced Stella?

 

[Redwulf]

This is my take on 02 in beer, some of it may be fable, legend or just plain wrong...

1. Exposing cold beer to oxygen is not really an issue for short periods with some exceptions. Many of us bottle from an open bucket and it can take an hour or so to bottle 23L of beer. The risk comes when the interface between the air and the beer is forced to interact through splashing or stirring, the warmer the beer the higher the risk.

2. The simple answer is yes. if you are naturally carbonating then any oxygen in the vessel is going to be away from the beer (due to the joys of thermodynamics results may vary). When kegging purging the keg before and after the transfer is considered sensible.

3. Hoppy pales and NEIPA are very prone to oxygen. Generally neutral grain bills often with high protein malts like wheat and oats with large dry hop charges mean that you'll notice it going bad long before a maltier less hoppy beer like Bitter or Stout. When brewing IPAs or NEIPAs I tend to make sure I can do a closed transfer and try to make sure any dry hopping is done before fermentation has finished or make sure I purge after dry hopping

4. As someone else pointed out we've got 2 issues here.

The first point of risk is during the mash which is generally undesirable as oxygen can combine with tannins, lipids etc and carry over to the finished beer. HSA happens at a point below boiling but the point where it happens is open to debate. Good Practice is considered stir the mash gently and don't splash too much. Of course this is home brewing so for every brewer who cares about this or has lost a batch 5 more have got away with it.

Once the wort is boiling the risk is significantly reduced if not negated completely and stirring is encouraged to stop scorching and at the end of the boil to gather the trub into a neat pile. Its also desirable to get some oxygen into the wort during transfer to the FV to encourage a fast fermentation.

The next point of risk is during fermentation and packaging and in my mind starts when the Krausen drops and remains until the beer is safely packaged in bottles or kegs. From that point its advisable to not open the FV or agitate the beer too much.

Most people worry more about the cold side, I personally think HSA is the bigger and least understood issue.

5. In most cases the effects of oxidizing beer is probably not going to be noticeable for a 4-6 weeks, so unless you've got a very sensitive pallet you probably would never notice it. Certainly round here a keg barely lasts a month, 2 if it needs conditioning. I've had one batch of NEIPA that I noticed deteriorated after about 3 weeks on tap (5 weeks in the keg) and a couple of batches where I had a stuck mash and would probably have gone bad if they'd lasted much longer

 

[SilverShadow]

Great info there redwulf, many thanks

I tend to only expose my beer to O2 briefly when dry hopping & kegging, so no real worries there by the sound of it.

For my current brew I gave the mash a good few mins gentle stiring at 70'c before insulating it, and got the OG to within 1 point of required (1.070), so I'm hopeful this will turn out well without undue exposure