Hot side aeration

[booldawg]

Someone helpfully left a comment on my blog about this. They noticed from my pics I run-off the sparge into the boiler from height. Apparentley this can lead to stale tasting beer. I will run off through a length of tubing to cut down on aeration. Is this common practise? as I was unware of it until now.

[The Mighty Badger]

There will be others who know more, but there have been a couple of threads about this (not so long ago?). As I read things the great and good around the patch here appeared to agree that the theory behind hot side aeration is a load of cobblers.

I'm sure someone will expand / correct...

[Aleman]

Hot Side Aeration was a hot topic back in the early 90's and has continued to be one ever since. With all the research I have done, I have come to the conclusion that it does exist but using British malt and brewing British beers we are exceptionally unlikely to experience the classic 'wet cardboard' aroma/taste that is typically associated with HSA. . . . The evidence seems to point to US 6 row Barley having a higher level of the precursors of Trans-2-Nonenal which make mashes made with 6 row malt more susceptible to 'splashing around' when hot . . . Especially if being used to make a pale pilsner type beer . . . darker beers have a higher level of antioxidants than pale.

HSA does exist . . .you are just very unlikely to experience the classic symptoms in a British brewing environment. . . .

[Seveneer]

HSA does exist . . .you are just very unlikely to experience the classic symptoms in a British brewing environment. . . .

Agreed, but it's worth taking whatever precautions you can to avoid tempting fate

/Phil.

[Matt]

I think the "HSA doomsayers are talking out of their elbows" standpoint was from Daab, who'd deliberately done everything you're not supposed to do - splashed hot wort around etc - and the beer was fine.

Like Seveneer, I still guard against it though, just in case.

[Whorst]

I've read many opinions on this. Some people say it's bullshit, others say it really exists. I splash around and have NEVER experienced hot side aeration, which makes makes me believe it's myth.

[steve_flack]

I ain't seen Russell Brand in person myself either so maybe he's a myth too. (Maybe we're not that lucky though)

[Gurgeh]

You're such a Scientist Steve!

As a mathematician I can safely say that there is at least one Russell Brand and there is at least one Brewers house that he does not exist in. therefore there is at least one Brewer who is considering himself lucky.

Hold on - phone's ringing...



HSA has existed, may well exist and might well continue to exist. if you've got a dodgy sack of 6-row, then don't splash. (Unless you like licking wet dogs - who can tell in America?)

Gotta Go - rocking horse has just done a #2 on the bloody carpet again

[Aleman]

As I alluded to earlier, it is all to do with the level of precursors of Trans-2-nonenal in the malt . . . 6 row is higher than 2 row, and a good few years ago the levels in 6 row were significantly higher (it can be reduced during malting ). all of a sudden the Splashing beer around when hot causes HSA/wet cardboard in beer topics, on a lot of the fora. As the maltsters have reduced the levels of precursors, the likelihood of encountering the classic HSA symptoms has been much reduced . . . if it ever existed in a British brewery (Although I do know of one brewer in the UK who Has experienced it . . . No not me)

I do however reduce the splashing as much as possible myself

[BarryNL]

Basic Brewing radio did a lot of experimenting back in 2006 on this topic. I think the main conclusion was that its a bit of a myth, but check out the archives for the full details.

[Horden Hillbilly]

I read in a home brew book a while ago (possibly G. Wheeler) that cool wort will absorb air quicker & more readily than warm/hot wort. I don't think anyone has come up with a definitive answer, but I do use a tube myself when sparging as seen here, 3rd pic down just in case.

[Jim]

The whole concept of HSA seems odd to me.

We go out of our way to get oxygen into the wort before we pitch the yeast, which then mops it all up, so what difference does it make if it gets in before the wort's cool? Is the heat supposed to cause the dissolved oxygen to undergo some kind of irreversible reaction?

[Aleman]

Its not oxygen per se that it the issue but the oxidative reactions that take place . . . later in the brewing/maturation phase further redox reactions take place that are not favorable. If we minimise the contact with air throughout the brewing process we improve the stability of the beer for the long term.

[Neal]

Interesting topic and one I'd never considered before, mainly because I thought hot liquids could only hold negligible amounts of O2. Boiling for a prolonged period directly after mashing must mean any O2 picked up during wort transfer is removed pretty quickly anyway. Also how does the aeration prior to the addition of yeast not cause problems?

[Aleman]

Lets make one thing clear. it is very unlikely that we will experience this this is purely esoteric discussion

<Geek Alert>

The issue is not with aerating hot wort, after all that is done in a lot of commercial breweries with internal calandrias in the kettle, and also in aerating hot wort on the way to the plate chiller. The issue specifically appears to have applied to aeration of the mash, with excessive stirring and splashing about . . . The mash does absorb massive amounts of oxygen over the 90 minutes which 'gets stuck' in the mash as oxidised compounds . . . as conditions change in the beer with storage, these oxidised compounds release electrons (Becoming reduced) and other compounds accept those electrons (becoming oxidised). Now if a malt has high levels of (IIRC) S Methyl Methionine (SMM) then these will oxidise to (eventually via an oxidative pathway . . . there is also an non oxidative pathway as well ) trans-2-nonenal which has a taste threshold in the order of parts per billion . . . so it doesn't take a lot of extra SMM to have an effect.

The other thing to consider is that during the boil conditions change in the wort quite dramatically pH falls for one thing . . . and as others have noticed the potential for oxygen to dissolve into the wort is very much reduced (I should add that it is already pretty low at mash temperatures . . . it is the chemical absorption in the mash that is the problem), which makes the chemical absorption of the oxygen much less of a problem. So by only exposing a small surface area of mash to the air, not stirring once doughed in, and covering the mash tun we are already reducing the absorption of oxygen.

</Geek Alert>