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Hot Side Aeration

When I did my first all grain Saturday, I didn’t have hose clamps for the tube from my mash tun to the boil kettle, so I used zip ties. Even with 3 zip ties I still got air in the line. Since the boil will be reducing the oxygen, is this air in the line going to affect my beer?

did you have the end of the hose in the wort or was it splashing? if it was in the wort i don’t think you have anything to worry about.

Are you splashing this much? → http://www.youtube.com/watch?v=wD_49kfVJeE Note: 5:20 mark in the video. Allagash Brewery doesn’t seem to worried.

I had the kettle end submerged, but that woried me when the bubbles came up from the bottom. Oh well, I’ll just have to keep my fingers crossed for the next 5-6 weeks. :cry:

According to Dr. Charlie Banforth, Chair of UC Davis Brewing program, hot side aeration is pretty hard to do. Basically he hints (actual will come right out snd say) that you would literally have to splash the crap out of your beer to really have an effect.

You can find the Brew Strong show (thebrewingnetwork.com) where Jamil and J.Palmer interview Dr. Banforth and have an extensive converstation with him about it. They both seemed convinced that it hot side aeration is one of the last thing a homebrewers should be worried about.

You should be fine! Good luck!

I’ll let you know in a month. My last beer included 3 lbs rye malt. Towards the end of lautering, I was splashing and stirring, trying to get a good flow. It’s full of protein and oxygen.

[quote=“Cheshire_Cat”]According to Dr. Charlie Banforth, Chair of UC Davis Brewing program, hot side aeration is pretty hard to do. Basically he hints (actual will come right out snd say) that you would literally have to splash the crap out of your beer to really have an effect.

You should be fine! Good luck![/quote]

That is great news! Now I can relax and watch it ferment! Thanks for the reply and especially the link!
:cheers:

You will be fine. I get air in my mash tun hose all the time as the runoff is finishing. I make no effort to reduce splashing or air in the line during both first runnings and sparging and I haven’t noticed any oxidized flavor in my beer.

I stir the crap out of the beer while it’s chilling also.

It’s a myth.

I thought this subject was put to rest.

Other people said that there is no such a thing.

[quote=“Thirsty_Monk”]I thought this subject was put to rest.

Other people said that there is no such a thing.[/quote]

It has been for the most part. Myths still linger amongst new brewers, unfortunately.

It is not a myth, it has been scientifically proven. But whether it is detectable in your beer is your decision. With most homebrews that get drunk quickly it probably won’t be noticeable.

IIRC during the tour at New Belgium, the wort is run over a flash boiler as it cascades into the boil pot. Seem to me this would create a lot of “hot side” aeration.

Where has it been proven? Do you have a link? I would like to check it out because I still am not one way or the other…

HSA is a myth. Any potential ill-effects are dealt with by a healthy ferment.

I couldn’t find the precise journals, but these experts’ thoughts. Anyone have any proof tht it doesn’t happern?

From Dr. George Fix in HBD # 1047
"Negative effects due to HSA are usually reflected in a flavor the
Germans call “Herbstoffe.” Roughly translated this means “grain bitter”
or “grain astringency.”

There are some theoretical considerations which suggest HSA should
be a nonissue. Ironically, the same issues arise in a project I am
currently working on which involve beers very far removed in character
from Lambics. Herbstoffe arises from the presence of what could be
called HSA aldehydes. These in turn arise from the interaction of
ethanol in beer (as well as some other things) and products which were
oxidized on the hot side of wort production. The HSA aldehydes have
been isolated, and definitely display “grain astringent” flavors.
Moreover, it has also been shown that most Saccharomyces will ignore
them. Thus, in most beers, if present, they will spill over into the
finished beer and display Herbstoffe."

From Steve Anderson in HBD #5093:
HSA is a term that includes oxygen uptake in the mash & boil both. This
is in contract to cool-side aeration after the chill. Some studies in the
late 1968 and up to recent years attempt to trace out the fate of oxygen
in wort & beer and make decisions about there relative “badness” based on
their chemical fates. Anyway the early papers (and many since) indicate
that HSA oxygen has negative impact on flavor and flavor stability.

Chas Bamforth published a terrific paper in JIB about 5 years ago
calculating the enzymatic and catalytic pathways for various oxygen
species in the mash, then correlated his estimate with published studies
of the total O2 uptake in the mash.

Despite the fact the oxygen is not very soluble at mash temps and above -
many times the saturation level of oxygen is chemically compounded with
the mash during the mash. Nearly all of this oxygen transpires through
the air-mash boundary. Bamforth calculates that the catalytic processes
in the mash are sufficient to use up saturation levels of oxygen in a
matter of seconds !! So the mash is almost devoid of oxygen and
Henry’s Law of partial pressures forces atmospheric O2 into the mash.

Bamforth doesn’t directly address the issue of O2 uptake in the boil,
but if we assume the enzymatic mechanisms are lost and the metal ion
catalytic mechanisms (which are the stronger ones) are enhanced by
temperture, then the boil is probably at least as bad in terms of
oxidized products as the mash.

All this oxygen ends up compounded with wort constituents. Oxidized
oils are probably primarily produced in the mash by the action various
lipo-oxygenase enzymes. These damaged oils break down producing the
trans-2-nonenal cardboard aroma and other aldehydic aromas.
Quantitatively phenolic compounds are the greatest destination for this
oxygen in wort. Simeple phenolic compounds often have pleasant fresh
flavors - or at least innocuous ones. Oxidized phenolics are more
bitter and will polymerize and eventually produce astringency. They
also are removed to some extent in the break material and in the
“dregs” left behind in the lagering process. Fining materials like
PVPP will remove oxidized phenolics too. Many other materials in
wort are oxidized in the mash & boil too.

After the chill, a fermentation is created and the yeast during their
anaerobic ferment have a dilemma - they are required to chemically
reduce the material in their environment to achieve a redox balance.
The major destination of all this reduction is in the creation of
ethanol from acetaldehyde, but also the conversion of other aldehydes
into alcohols and some other very flavor positive effects. Yeast
also leave a little (2-15ppm) of sulfite behind in the beer and
sulfite is an antioxidant. My hunch is that lager yeasts are
the better sulfite producers, and most ale yeasts - not so much.

More recently Morton Meilgard(sp?) has noted that some of the
extreme oxygen elimination methods developed for commercial brewing
have not proven to create a measurable improvement in flavor IN
COMMERCIAL BREWING.

Note that the amount of O2 exposure is largely related to the surface
area:volume ratio of the mash tun & copper. Also the amount of
“splashing” and transfer activity must impact this significantly.
Small HB tuns will therefore have a lot more potential for HSA,
than deeper commercial tuns. Oxidation is clearly more problematic
the smaller (shallower actually) the mash.

=========

So here are the practical points -

Preboiling your mash water will NOT have a significant advantage.
Most of the HSA oxygen is introduces through the surface (which
increases with stirrig & splashing).

I’ve idly suggested in the past that we could mash (&boil) under an
inert gas layer - and this really is possible. I haven’t tried it.

We could introduce an oxygen impermeable barrier to reduce the surface
area of the mash & boil. Aluminum foil or a food grade plastic layer.
80% coverage would bring HB mash tuns into the same surface:vol
ratios as commerial tuns. OTOH stirring & transfer are still
problematic.

Add sodium or potassium metabisulfite as anti-oxidants to the mash.
This method has been used in many tests and has been recommended by
some of the German brewing researchers. I add 1/2 crushed campden
tab per gallon of finished beer to the mash. I’ve done this with
some regularity in recent years and the resulting beer is a little
fresher, and metabisulphite has a notable impact in reducing the
color of light colored beers (another impact of oxidation).

I also think M.Meilgard has a point. Well made fresh HB seldom
has an oxidation flavor problem when young, probably due to the
terrific impact of the yeast. Bottle conditioned HB also seems to
have terrific shelf life if not mishandled. OTOH kegged or force
carbonated HB sometimes doesn’t last so long. Certain beers
have notable aging problems - some of the dark malts in a munich
of n-bock seem to sometimes go south in a hurry.

Do try an HSA reduction method and evaluate it for yourself. I
think the metabisulfite addition makes a clear enough difference,
but it takes a little judgement to decide when it is called for.

-S (Steve Anderson)

And from Dr. Bamforth himself ( http://www.thebrewingnetwork.com/shows/475 ):

“He (Bamforth) was a quality manager at Bath
[sic?] Brewery near Liverpool, brewing Carling Black Label. His brewery’s
Beers were the ones that they could identify every time as harsh and grainy.
They cut down the amount of oxidation in the brewhouse. It didn’t affect
stability, but it did affect the flavor and improved it a lot; unfortunately,
customers sent it back because they didn’t like it any more!”

Extensive post.
God bless George Fix but our understanding of brewing process reached another level.
I clearly recall what Benforth said that there is not souch a thing as HSA.

From Dr. Bamforth himself ( http://www.thebrewingnetwork.com/shows/475 ):

“He (Bamforth) was a quality manager at Bath
[sic?] Brewery near Liverpool, brewing Carling Black Label. His brewery’s
Beers were the ones that they could identify every time as harsh and grainy.
They cut down the amount of oxidation in the brewhouse. It didn’t affect
stability, but it did affect the flavor and improved it a lot; unfortunately,
customers sent it back because they didn’t like it any more!”

He seems to support the existence and significance of hot side aeration.

I’m not sure where I saw it, but I’m pretty confident that one of our esteemed brewing scientists claimed that a vigorous boil and healthy ferment would deal with excess oxygen uptake.

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