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Hot. Side. Aeration

So I have been trying to pinpoint a flavor that is coming through in the majority of my beers. Some people, BJCP-certified in my club even, can’t pick it up. But I know it. Well. And haven’t really been able to pinpoint it.

After tasting my latest IPA experiment, I noticed it AGAIN. Its a somewhat cardboard, tart, papery off flavor.

When my boil is complete, I have been immersion chilling, as for a 5 gallon batch, my plate chiller is just not worth the trouble. Until recently, I would cool it down to pitching temp or near it with the immersion. Lately, I’ve been partial chilling below 140 to stave off DMS, DUMPING the kettle into a fermenter, then placing in the fermenting fridge to get the beer exactly to pitching temp (albeit a bit more slowly), THEN once its at pitching temp (well below 80 always), dumping and aerating into a clean, sanitized fermenter (the second dump to assist with intentional aeration). In both methods though, I have been directly dumping wort, usually above 80 degrees, out of the kettle into the fermenter, sometimes a bit vigorously. I will leave as much trub as I can behind (I don’t whirlpool), but don’t really worry about it, as with my pre-pitch, post-chill transfer, I can decant off the trub.

Either way though, aldehydes are forming from introducing the beer to too much oxygen when its above 80 degrees right? (it is rare that I would chill with my IC below 80, even with the old method). If the aldehydes can’t be boiled off, they will stay in the beer until it gets to mah belly.

Has anyone else made this mistake, or corrected it/something similar and noticed improvement??

I need to read How to Brew all over again…I spent my first 10 batches boiling with the lid ON because I had it in my head that I didn’t want to lose volume (this is before Ray Daniels schooled me that the TOTAL GRAVITY in the pot cannot change!! Ie, no you are not losing WORT with boil off!!)

Seems that chilling to 80 degrees isn’t enough? I’ve always shot for 70 or less with my IC. I’m curious why you aren’t shooting for a lower temp? You may very well be introducing oxygen when the wort is too warm.

I highly doubt it’s HSA. HSA is a myth for homebrewers. And I don’t think you’re adding too much oxygen, it’s really difficult if not impossible to get more than 8ppm unless you’re using pure O2. Plus yeast like oxygen unless you use way too much pure O2. You might be getting excess aldehydes from letting it ferment too warm or by not giving it enough time in the fermenter. For ales you really want to pitch the yeast in the mid to low 60’s.

Cardboard favors come from oxygen getting into the beer post fermentation

HSA is one of the flavors I have a hard time picturing. I’d love to taste some beers where that fault really stands out.
I was worried about it, too, but probably more interested in leaving trub behind, so I’ve been siphoning my beer after whirlpooling. Hard to say if that was responsible for amy improvements-i try to continually improve my technique so lots of things have changed…
I used to like dumping from the kettle because it aerates pretty well, but I started doing all my fermentations in carboys, which would make dumping a challenge. Besides, it’s too hard on the back.
Siphoning is no biggie, and I make sure to barely put the hose in the top of the fermentor so the wort falls from a height to aerate.
And of course I do it cold.

Have to listen to this again as its full of sciencey stuff, but the head of brewing science @ UC Davis seems to disagree

Sorry, my post wasn’t worded quite right. I do chill down to the mid 60’s for ales and 50’s for lagers, but I only partially chill with the IC. The primary reason to chill quickly is get DMS precursors and proteins/cold break to settle. As I chill the rest of the way in my fermentation fridge, then dump into a new fermenter, decanting off the settled trub, I take care of the break that way. To precipitate the DMS, one only needs to chill it below 140 quickly.

Anyway, I’m going to see if I can get rid of this by just attaching a hose to the valve on my kettle and gravity feeding to the 1st fermenter to avoid aeration. It was just one more step before, but it seems like a worthwhile one to add.

I’ll have to watch that soon. But for the last few years everyone seems to have debunked the likelyhood of HSA happening to homebrewers. When i was in school at Brewlab training and analysis they seemed to believe that it was extremely unlikely on a homebrew scale with ales. Hopefully some other forum members chime in on the subject

When people say hot side aeration, they really mean oxidation, and oxidation is no myth. there’s also no doubt that oxidation is sped up/worsened by higher temperatures, that’s simple science. The flavor hes describing sure sounds like oxidation to me.

HSA is a “myth” in the sense that homebrewers have historically freaked out about it more than is warranted. Stirring your mash too much for example is unlikely to be a real problem, the oxygen will get driven off in the boil before it has a chance to do harm. THat doesn’t mean it can’t happen though.

I don’t claim to have done a scientific comparison, but my opinion as a huge ass nerd is that if he’s vigorously pouring before his wort is fully chilled, and then letting it sit before pitching while he waits for it to drop to fermentation temperature, there’s a reasonable chance during that pouring and sitting time some degree of oxidation is occurring. Its also entirely possible something else in the process (post fermentation) is the culprit.

But if I were the OP, I would suspect oxidation.

[quote=“Nate42”]HSA is a “myth” in the sense that homebrewers have historically freaked out about it more than is warranted. Stirring your mash too much for example is unlikely to be a real problem, the oxygen will get driven off in the boil before it has a chance to do harm. THat doesn’t mean it can’t happen though.

Well said. Especially for a huge ass nerd :slight_smile:

I had always operated under the premise that it was a red herring, and if you followed basic brewing procedures described by the HB Jedis (Palmer, Papazian, Zainasheff), you didn’t really need to worry about it.

However, I always take some sort of shortcut or miss something. The vigorous dumping into the fermenter probably wasn’t that huge of a deal when I chilled to pitching temp (or at least below 80), but now with my partial chill, its probably more of a concern.

My understanding is that if beer/wort is introduced to large amounts of oxygen when it has a temperature ABOVE 80, the aldehydes can form and boom, your beer is a fedex box. If you are going to BOIL it, the aldehydes are boiled off, but this is the point in my process where hot side becomes cold side, so no more boiling.

The reality is, attaching a sanitized hose to my brew kettle, and gently draining into the fermenter is really not a big deal, and I should get off my lazy @$$ and add one more step so I don’t have to drink Dunder Mifflin beer.

Rightly or wrongly, I have always associated Sam Smith NBA as having this characteristic. Would be curious in hearing from others on that point.

As for HSA being a myth, I don’t think that’s quite right – oxidation of the wort on the hot side can happen on the homebrew scale. My understanding is that it essentially destabilizes the beer so as to effectively reduce shelf-life. If you drink your beer quickly enough, you may never notice it. If you are like me and you tend to keep beer around for a longer time, over time you may notice that cardboard-box flavor rearing its nose if the wort was oxidized. But like a previous poster said, I think the general consensus is that we may over-worry – non-vigorous stirring of the mash is unlikely to cause problems. However, I wouldn’t free-pour hot wort into a bucket after the boil.

[quote=“Pietro”]My understanding is that if beer/wort is introduced to large amounts of oxygen when it has a temperature ABOVE 80, the aldehydes can form and boom, your beer is a fedex box.[/quote]Got a reference for that 80F?

I’ve poorer hot wort post boil into another kettle for chilling. This was when I did ice baths, and my megapot was to big for my sink. Never noticed any faults, even after a couple months. Maybe I got lucky then… But that was a long time ago, so maybe my palate wasn’t keen enough

I was wrong to call it a myth, but i would suspect another reason for Trans-2-nonenol flavors before HSA. I’d like to hear shadetrees opinion on HSA

Here is a good read


@ Scoggin, it could simply be that this particular beer is ‘green’, as I bottled it less than a week ago. But its a flavor that I find in many of my beers, and while subtle, it is annoying the s#!t out of me.

the only other thing I can think of is sometimes I will pour priming syrup into the bottling bucket ON TOP of the racked beer as opposed to pouring the syrup in first, then racking on top of it. I think I actually CO2-purged this batch tho.


And thanks to all for the advice! Hopefully I can get this 'figgered out.

also @ Scoggin, yes!! he did say that the boil does get rid of most of the compounds responsible for HSA, HOWEVER, in my process, there is still some ‘hot side’ process AFTER the boil. All I’m saying is I should keep post-boil splashing to a minimum if I am not going to chill all the way to pitching temp.

[quote=“Pietro”][quote=“Shadetree”][quote=“Pietro”]Got a reference for that 80F?[/quote][/quote][/quote]I was looking for a real reference, not some guy’s website where he just makes an assertion with no backing documentation. :wink: Can’t see why 80F would be a magic number.

I have always assumed that HSA was a myth but I generally don’t take chances with the beer and it’s relatively easy to avoid the risk altogether. I chill with an IC and get usually get wort temps down to 60-70 depending on the season. While the beer is over 100° (can’t remember where I heard that temp), I stir gently during the chill. After the chill I will let the BK settle in an ice bath in the sink to chill further and settle and then I rack from BK to primary to leave all of the schputz behind. Then I use an airstone connected to an O2 tank and oxygenate that way. I also rack to secondary (pretty much every batch) and I do not purge the secondary with CO2 first. I try to transfer with as little splashing as possible. It eventually gets racked again to a keg (also not purged) so all along the line the beer is treated ‘gently’. What does HSA taste like? If oxidation is post-fermentation exposure to air and tastes like cardboard, what would HSA’s flavor profile be like? Not sure I have ever tasted it.

HSA usually was a concern because it supposedly affected long term stability of beer. Maybe I’m throwing the wrong term around (happens a lot), but I’m basically saying my beer tastes oxidized…in trying to find out where I may be picking up extra oxygen in my process, I found this one potential flaw. However, the more I’m reading, the more it seems that the vigorous, healthy fermentations I’m getting should drive off any flavors and OXIDATION really only happens in finished beer.

So now I’m even more lost as to what is causing this off flavor.

It could be that its very young beer (sample was chilled and drunk 6 days after bottling), but I recognize this flavor in aged and young beers of mine.

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