Hot side aeration?

[Buffers brewery]

Think I’ve made an error

Just finished a brew day. This is my fourth or fifth brew after I changed from a gas fired kettle to electric. The change of vessel resulted in me changing my arrangement for recycling the wort for the last 15 minutes of the boil and cooling. The outlet pipe is above the boiling wort surface and results in the creation of a lot of foam!
I have been disappointed in recent brews and am now wondering if that’s because of hot side aeration and should I be changing the return pipe length so it dips into the wort (like my previous arrangement).
Thoughts.

 

[MashBag]

I would.

Have to ask you, why are you doing it at all?

 

[Buffers brewery]

Recirculate for the last 15 minutes of boil to make sure pump and pipes are sanitised for when I circulate during cooling (immersion cooler) and try to coax a bit of a whirlpool before I leave it to settle for an hour or so.

 

[The Baron]

I re-circulate with my AIO using the upper pipe as you are suggesting. What I do is whirlpool with the hops in a bag then re-circ onto the bag to keep it flowing/agitating the hops for 35/40 mins.
It has never caused me any issues at all I then stir it with a paddle to create a fast whirlpool after removing the hops then leave to cool naturally.
I have done this for years and never had any issues so I would say you would be ok but you could add a short length of pipe so it exhaust just above the wort level and not from a height if it bothers you

 

[Buffers brewery]

I re-circulate with my AIO using the upper pipe as you are suggesting. What I do is whirlpool with the hops in a bag then re-circ onto the bag to keep it flowing/agitating the hops for 35/40 mins.
It has never caused me any issues at all I then stir it with a paddle to create a fast whirlpool after removing the hops then leave to cool naturally.
I have done this for years and never had any issues so I would say you would be ok but you could add a short length of pipe so it exhaust just above the wort level and not from a height if it bothers you

Thanks for that @the baron . My latest brew created a thick creamy foam on top of the boiled wort that did not dissipate after an hour hence my concern

 

[The Baron]

just turn it down a little if you have it on full bore also use a length of hose/tube if it is comong from a height.
Ps aeration of the wort is not a bad thing as it is prior to fermentation

 

[Buffers brewery]

Yes, I have now extended the hose length so the wort is directed onto to side of the kettle and below the wort surface. That was how my previous set up worked.
Thanks

 

[MashBag]

I have never done anything like that (it seemed pointless years ago) and have never had an unintended infection.

 

[hoppyscotty]

Hot side aeration is definitely a hotly debated topic. I personally have never bothered worrying about it and not noticed any obvious detrimental impacts on the beer but I guess if you've noticed a change in yours then you've got to consider every potential contributing factor. However if you've changed your brew system then there inevitably will be some adjustments to your recipe that has to be done to suit the new system. I recently listened to a podcast where they were discussing scaling up from a homebrew level to larger commercial production system and there is more to it than just scaling up your recipe volumes.

This is a good YouTube video I recently stumbled on tailing about dissolved oxygen which covers hot side aeration too - executive summary is that Dissolved Oxidation is a thing, but not at homebrew level.

 

[Agentgonzo]

This is a good YouTube video I recently stumbled on tailing about dissolved oxygen which covers hot side aeration too - executive summary is that Dissolved Oxidation is a thing, but not at homebrew level.

Good to know. I'll watch this later. I have often suspected that there is a fair difference between homebrew and commercials scales and therefore a lot of "rules/best practices" for one may not necessarily apply to the other, so it's not just as simple as quoting research papers.

 

[The Baron]

Very interesting Video but unless I am missing something where does it explain about hot side aeration. He does seem to be talking about beer all the way through again unless I have missed it in the vid.
He does mention the expensive DO meter but that is just a measuring tool so as you only have 20-25 minutes to sort this how do you remove the DO already in the beer you have measured?.
So my question is how critical is hot side aeration for the homebrewer as I have always been taught that the yeast needs this and I have never worried about it.
Oxygen after fermentation or maybe even in the last parts of is a No No is what I have been taught too.
Open for debate chaps

 

[Buffers brewery]

I'll let you know in 6 weeks or so. I've just modified my kit to eliminate the thick frothy head I had on the top of my wort after post-boil cooling. I have a beer in a keg at the moment that suffered the frothy top and to me doesn't taste as it should though still drinkable. I'll be able to do a comparison. It will involve drinking beer but I can do it

 

[Sadfield]

I too, don't see that it cover hot side aeration though, very much about DO post fermentation. Given that he talks about oxidation in beer, not wort. It's worth keeping in mind how chemically different the two are.

Interesting video though. Great that he address cumulative effect. Something that we should be mindful of when dismissing things that look inconsequential in isolation.

@the baron DO can't be removed, it's more about fault finding and prevention in the process. A 25 minute window to make the measurement.

Back to @Buffers brewery problem.This is very informative and holds the key to answering some of the questions in the thread. Temperature.

"The oxidation rate increases with temperature, but the ability of a solution to dissolve oxygen decreases with temperature. This means that very hot wort does not contain enough oxygen for oxidation, whereas oxygen-rich wort at the beginning of fermentation is too cold to permit oxidation. Thus, HSA is a problem only in a temperature band somewhere below the kettle boil and above the heat-exchange temperature."

https://www.google.com/amp/s/beerandbrewing.com/dictionary/amp/4vQFCvGmuD

 

[Buffers brewery]

Interesting @Sadfield . My process (that I have now changed back to my previous set-up) involved using an immersion cooler while recirculating down to 80C then pausing (cooling and recirculation turned OFF) for 30 minutes after final hop addition. Then cooling and recirculation restarted down to pitching temperature, usually about 30 minutes. While there was a significant amount of foam on the wort at the end of the boil it was still there after cooling and leaving to settle for over an hour.

 

[Sadfield]

Hopefully your hunch is correct and the problem disappears.

Having changed heating source, the other thing to consider is thermal stress on the wort. Indicators would likely be signs of scorching or increased losses to evaporation. Essentially, introducing a more cooked flavour.

Or, the cumulative effect of both heat source and HSA.

 

[Buffers brewery]

Hopefully your hunch is correct and the problem disappears.

Having changed heating source, the other thing to consider is thermal stress on the wort. Indicators would likely be signs of scorching or increased losses to evaporation. Essentially, introducing a more cooked flavour.

Or, the cumulative effect of both heat source and HSA.

Good point. I have changed heating type from gas to electric and I do get a bit of “burnt” crud on the kettle heater after a brew. My water is very hard (don’t tell @peebee ) so just heating my strike and lautering water leaves a ”chalk” deposit. I try (and fail) to reduce the crud by stirring during the heating stage of the boil. It’ll be interesting to see how my latest brew turns out as the aeration aspect has been addressed and is back to “normal”.

 

[The Baron]

I too, don't see that it cover hot side aeration though, very much about DO post fermentation. Given that he talks about oxidation in beer, not wort. It's worth keeping in mind how chemically different the two are.

Interesting video though. Great that he address cumulative effect. Something that we should be mindful of when dismissing things that look inconsequential in isolation.

@the baron DO can't be removed, it's more about fault finding and prevention in the process. A 25 minute window to make the measurement.

Back to @Buffers brewery problem.This is very informative and holds the key to answering some of the questions in the thread. Temperature.

"The oxidation rate increases with temperature, but the ability of a solution to dissolve oxygen decreases with temperature. This means that very hot wort does not contain enough oxygen for oxidation, whereas oxygen-rich wort at the beginning of fermentation is too cold to permit oxidation. Thus, HSA is a problem only in a temperature band somewhere below the kettle boil and above the heat-exchange temperature."

https://www.google.com/amp/s/beerandbrewing.com/dictionary/amp/4vQFCvGmuD

Thats how I found the Video Sadfield I could not see where it related to Hot side at all it was all about the Beer, re the DO thats why he did not mention how to remove it then and how this applies to us homebrewers I do not know apart from what we already do to stop oxidation in the beer

 

[MashBag]

My water is very hard (don’t tell @peebee ) so just heating my strike and lautering water leaves a ”chalk” deposit.

I have recently seen the benefit of water treatment. And it's isn't hard.

Can I tell Peebee

 

[peebee]

Can I tell Peebee

Err ... no need, I've seen. But I don't know how I've got a reputation for not being nice about water "hardness" ... It was less than a week ago when I was being pilloried by a very eminent water chemist for talking about "soft" water. He's the one who'll sneak up and bite your head off, not me ... shh, I think I can hear him? I'm off. ...

 

[Agentgonzo]

Hot side aeration is definitely a hotly debated topic. I personally have never bothered worrying about it and not noticed any obvious detrimental impacts on the beer but I guess if you've noticed a change in yours then you've got to consider every potential contributing factor. However if you've changed your brew system then there inevitably will be some adjustments to your recipe that has to be done to suit the new system. I recently listened to a podcast where they were discussing scaling up from a homebrew level to larger commercial production system and there is more to it than just scaling up your recipe volumes.

This is a good YouTube video I recently stumbled on tailing about dissolved oxygen which covers hot side aeration too - executive summary is that Dissolved Oxidation is a thing, but not at homebrew level.

For those watching the video, is worth pointing out that his calculation of 100ppb being 0.45ml of air in 1000L of beer is incorrect. His calculation fails to take into account that the density of air and the density of beer are different (which they clearly are).

The correct value of 100ppb is: 81ml of air in 1000L of beer

Calculation:
100ppb = 0.1g per 1,000,000g (or 0.1g per 1000kg) (defined by weight, not volume)

Density of beer is close enough to 1kg/L
Density of air (STP) is roughly 1.225g/L

0.1g of air is (0.1L / 1.225) = 0.081L = 81ml of air.

Therefore 100ppb of dissolved oxygen is achieved by completely dissolving 81ml of air in 1000L of beer.

Still not of air-to-beer, but a lot more than he makes out.