Bizarre oxidation results

[truckpoetry]

So I had a couple of batches come out with the typical "wet cardboard" oxidation off flavors (albeit not too overwhelming) and I'm not particularly sure where it is coming from, but I want to isolate the problem and get rid of it (obviously). So here's what I have figured out as far as pattern:

I have done 16+ extract w/ specialty grain batches with no problem ever.
First all-grain batch was fine.
Subsequent all grain batches suffered from oxidation with two exceptions - belgian tripel and IPA, both obviously high gravity. Not sure how the gravity of the beer might affect the oxidation levels, but if so, I may stick with IPAs, Tripels, and Wee Heavy

Switched back to some extract/specialty grain for the meantime trying to make sure there is no other problem in my system and process (will let you know in a couple of weeks), but preliminary results appear to not suffer same issue.

Oxidation flavors are present PRIOR TO BOTTLING in the fermented wort, so I don't think it has to do with my racking and bottling procedure.

I've read the belief and disbelief in hot-side aeration... not sure if this is potentially what is causing it, or if there's something else entirely going on. Thoughts?

Thanks,
Cameron

[Bill Lawrence]

I am one of those who subscribe to the theory that hot side aeration is an urban myth, but that's just me (I suspect that Don will argue that one with me but he is very technical, I like flying by the seat of my pants just a little). Having said that, I don't go out of my way to beat air into my hot wort either, it never hurts to be safe. If you are pretty sure that the problem is not in the bottling then the next place to look is how well your fermentation locks fit on your fermenters and carboys (I am assuming that you rack off into a secondary fermenter after active fermentation has completed). If you ferment in plastic buckets, make damn sure those things seal up tight once you pitch your yeast.

I guess the other thing you should do is bring a bunch of your homebrew to the Christmas party. Wait until the assembled throng is well oiled then pass your efforts around and ask for feedback. In my experience, you will get better/useful feedback after people's inhibitions are loosened up a bit. Of couse, if you can't get rid of the problem, just present your ales as cask conditioned, I have read from many different sources that the oxidation that occurs in those British beers really helps the flavor.

[truckpoetry]

Ha - thanks for the "cask conditioned" tip.

I do rack off to a secondary fermenter after a week or so generally and let it sit in the secondary for two weeks, and that's usually a pretty quiet racking as well. Both fermenters are glass carboys and I use a stopper and airlock on each, pretty securely pushed in there.

Guess I will wait and verify with the next two (both extract) batches that there's nothing odd on that side of the process, and then try to go back and reverse engineer with another batch or three doing the all grain.

[Jimmy Orkin]

I do not believe hot side aeration is a big problem. Listen to this Brewing Network Podcast with Dr. Charles Bamforth:

http://www.thebrewingnetwork.com/shows/475

I do not rack to a secondary for ales. I just leave the beer on the yeast until it is completely done, 2 to 4 weeks. I then rack to my serving keg. Bottling at that point would be the same.

Racking off the good yeast to early brings many problems like diacetyl and acetaldehyde. You also induce some amount of O2.

I basically do the same thing for lagers. When the fermentation is complete, I rack to my bright tank (corny keg with shortened dip tube) to lager. After lagering I push the beer into my serving keg.

I do a diacetyl rest on everything.

My suggestion is to stop racking to a secondary.

Bill's bringing it to the Christmas party idea is also good.

[donniestyle]

Actually, I cannot say I can tell HSA if was staring me in the face. I know someone who believes they can. I can agree with others and say that it is probably not much to worry about. I take care anyway to be on the safe side. Generally in lighter beers oxidation is not preferred, and in heavier beers it adds character. This is true for any beers that need to be aged, like barley wines, imperial stouts, old ales, etc. I don't want to question your perception, but could you be tasting something else and associating it with oxidation? We just did the doctored beer session for the BJCP class, and everyone (including myself) had difficulty identifying aromas and flavors. I'd definitely like to try some and help you discover the flavors in your beers.

[truckpoetry]

OK OK I get it - everyone wants to try some beer... yeah yeah. If I do have some with the problem left, I may try to bring it around to some function or another. Or I could hand off a few at a meeting for later review. Assuming I don't drink them all.

As for the flavor, I don't notice much aroma, but the flavor is definitely that of a piece of wet paper, or wet cardboard, like I'm eating a McDonald's napkin that was previously soaked in otherwise tasty beer.

What I find unusual is that it is only happening on the lower gravity all-grain mashes, with the exception of the California Common I did which turned out great.

I am guessing there is something with the process that I am doing/not doing that is causing it, but I'm going to try to isolate it. First step was to make a couple of extract batches (partially to identify this and partially just to reuse a recipe I had without having to convert it and hope it turns out the same). If all three of those batches (Jalapeno, Christmas, Wee Heavy) turn out A-OK, I'll probably try something on the high gravity end again and make sure I can pull that off, and if THAT is OK, I will try something else and see if the problem resurfaces.

[Thors Brother]

Are you sure it is oxidation and not astringency from over sparging the grain? It is easy to over sparge a light beer and leave it with a flat lifeless dried out taste. This can taste very similar to oxidation. What efficiency are you hitting with your grain?

[chris mewhinney]

Yeah, I'm not convinced you're dealing with oxidation, either. Maybe I'm alone here, but I've NEVER had (or noticed) oxidation in a young beer, only in old ones where that fault has had time to develop. You indicate you detect it while the beer is still in the fermenter, which leads me to think it's something else (unless you're just throwing your wort around haphazardly during transfers...which I doubt). I also am usually able to detect oxidation in the aroma as well as the flavor, and you indicate you don't detect it in the aroma.

I think this esteemed group of beer knurds requires a little more information (recipe's and process) to make a call on this one. Now, everyone will tell you that I can't taste the difference between hop bitterness and malty sweetness, but I'm more than happy to do a taste test and talk through the process issues with you. If you can't wait for the Christmas party, I happen to live in Highland Village...you're welcome to stop by. I'll be bottling some beers sometime this weekend and that would be a good time, so let me know.

Chris

[Guerra]

I had an oxidation problem in my beers. Exp. when my Lighter Beers started getting >2 months old.

I think I have isolated my issue. I was going way over the top when it came to oxygenating my wort before pitching the yeast. I am using medical grade O2 and a 0.2 Micron Stone which which all good, but I was oxygenating for 5-10 min. I was putting way more O2 in my wort then it required. The "Pope" also mentioned over oxygenating on a show.

So what I have cut down, my oxygenating to about 1-1.5 min and the problem seems to have disappeared.

What type of oxygenating regime do you use?

Orlando

[truckpoetry]

Are you sure it is oxidation and not astringency from over sparging the grain? It is easy to over sparge a light beer and leave it with a flat lifeless dried out taste. This can taste very similar to oxidation. What efficiency are you hitting with your grain?

Hmmm you may be onto something here - I have had some relatively low efficiency ratings from 50-65% which has been another frustrating part of my "all grain experiments" so far. Perhaps that's part of it as well. I have a feeling that this may be much more likely the culprit due to the other factors mentioned (including the age of the beer and the fact that I can detect this taste in the fermenter as well...) However, I did get around 75% on a Northern British Brown Ale and still got similar flavors...

I will try to document my process a bit thoroughly and watch it on the mash/sparging front. I'll then come back and put more info and see if we can figure it out.

Thanks!

[Thors Brother]

Homebrewers who hit 75+% efficiency will have a high risk of grain astringency in their beer.

[chris mewhinney]

Regarding the following:

Homebrewers who hit 75+% efficiency will have a high risk of grain astringency in their beer.

While I understand the principly Thor's statement is based upon, I'm curious if anyone has any empirical evidence of this...and why it would be any different for a homebrewer versus a pro brewer? I've been trying all kinds of things to get my efficiency up from 68ish. For the last several batches, I'm hitting low to mid 80's and have not noticed any astringency. I think the biggest change I made was simply a finer crush, though I tweaked several other processes, too.

What experience do others have in this regard?

Chris

[Jimmy Orkin]

I have a 10 gallon Gott cooler with a plastic false bottom. With a single trip through the grain mill at HBHQ I would get between 65 and 70 percent efficiency. Using Leroy's mill and my new Barley Crusher, I get 88 to 90 percent efficiency. Jamil says that is too high. I might be getting stuff I don't want from the grain. The brew I did this weekend, I used 80% efficiency in my recipe and stopped collecting after I had the sugar I needed for my beer. I then topped up with water to get the preboil volume I needed.

I did not taste any problems with my high 80s efficiency but I tried the forced lower efficiency process to see if I could taste any difference.

I agree that commercial brewers are looking for the most efficiency they can get. Efficiency is money.

[Bill Lawrence]

There are two things one can do to avoid the dreaded astringency (which is not an urban myth). One is to never let your sparge water get above 170F, the other to to keep your ph around 5.3 or so. I recommend doing both. Did you ever wonder how it is that the Germans don't have astringency problems even though back in the day they all boiled the hell out of their grains when doing their decoctions? It's because the ph in the decocted mash does not rise like it does when fly sparging since all the liquid stays with the grain (infact the ph probably drops due to evaporation but I have never bothered to measure it).

Over the last year or so I have changed my sparging procedures and have gone to batch sparging. I did it mostly because it just works better with my set up but after reading up on it a bit, there are several other advantages. I use that 5.2 stuff, which is a buffer, to keep my mash ph in the right range. Every time I add water to my mashtun, I add a little of that magic powder to keep from having problems. I have found that my efficiency, while not 90%, actually got better doing batch sparging which probably means I had channeling while fly sparging. I am also using one of those Barley Crushers which is probably helping also since I can tell just by looking that I am getting a better crush than I was when using the crusher in the homebrew store. The bottom line though is that I don't have problems with astringency because I can easily contol the ph during runoff (instead, I have found other ways to screw up my beers but that is a story for another time).

Anyhow, I agree with the rest of the guys, what is probably going on is that you are extracting tannins from the grain rather than experiencing oxidation. I would again implore you to bring some of your brew to the Christmas party (or holiday party to be politically correct) and let some of the assembled pundits pass judgement. We have at least a couple of members who just love to pontificate on such matters, it will make them happy and you will hopefully gain some insight into what is really going on. Me, I don't know jack s#*t, I really just want to drink some free beer.

[truckpoetry]

Thanks to everyone who helped as well as had the lengthy discussions with me about this at the Christmas party... definitely not oxidation, some astringency, some other issues - Going to take the consensus vote and start by looking at water chemistry and controlling the mash a little better. Will let you know the results.