Off Flavor - Oxidation?

[stewart194]

Oxidation can also take form from of hot side aeration. BUt first let's look at Cold side aeration.


Look at this recent reprint of George Fix's work on Morebeer.


http://morebeer.com/articles/oxidation_in_beer


Note that hop oils combined with oxygen create off-flavors and that alpha acids also create off flavors.







Now read this article from the industry's foremost dissolved oxygen tester.
http://tapintohach.com/2013/12/02/h...ide-affects-the-oxygen-concentration-of-beer/






My latest thoughts are that the co2 tank is ruining my ipas... which is pushing me to pressurized fermenting.

Wow these are really great articles. Very interesting. Thanks for the reply! This CO2 thing would make a lot of sense in my case. I really started noticing this when I started kegging about 6 months ago. In fact I created a post about this and thought I was possibly "over carbing" my beer. I tried 2.6 vol, then 2.2, and everything in between and it didn't make any difference. Then I read about using 10 foot lines instead of the 5 foot lines I have, but I have not done this yet. But if it's been impure CO2 causing this, that would totally make sense.

Before I start changing my water and all of this other stuff, I will keg 5 gallons and bottle 5 gallons and see what happens. I do 10 gallon batches so this will be easy to do. In fact the last batch of IPA that I did before I started kegging turned out really well and did not have this problem.

Thanks again!

 

[stewart194]

And actually, a friend of mine and I just split a batch of English Pale Ale. Mine is in the keg with the off flavor, and he bottled his. So this will be a good test. I'll still bottle 5 gallons of a Rye IPA and keg the other 5 gallons.

Also, what if you used priming sugar in the keg to carb for 2 or 3 weeks, then put it on gas at serving pressure? Would that be a solution to this? Would any more CO2 get into the beer?

 

[grathan]

If you read the article, I think it says that bottling still gets oxidized. 1.) from the headspace air and 2.) from the cheap plastic bottle filler.

You could prime the keg with sugar. I believe the yeast produce pure CO2. It's still gonna push the flushed headspace impure co2 into the beer, but this should greatly reduce its impurity level.


You could try finding a better source for co2. I've switched to Praxair which sell 99.9% pure co2. I haven't had a bad tasting beer since switch (but I also haven't force-carbed any ipas with it yet either).
Another company that sells beer sepcific 99.9% co2 that has been filtered.
http://www.beveragecontrol.net/Carbon-Dioxide-CO2.asp

 

[stewart194]

Thanks again grathan. We do have a Praxair here. Glad to hear this fixed your issue.

Here are some other interesting articles that I found yesterday.

http://www.franklinbrew.org/wp/?page_id=98

https://www.homebrewersassociation.org/forum/index.php?topic=44.0

http://www.kegworks.com/faqs/Draft-Beer-Quality-Manual.pdf

http://www.kegerators.com/articles/installing-co2-lines.php

 

[grathan]

My main oxidation issue was actually caused by cold-crashing with too much headspace, but I have noticed an improvement in my beers since switching to praxair.

I still want to pressure ferment (to naturally carb) and transfer in a completely enclosed setup ( this is completely unessessary for my dark beers, I am drinking from 2 kegs today (dark beer) that are 7 months old with no hints of oxidation, I don't let ipas sit that long so no way of knowing how they would hold up. At the rate the stockpile seems to be growing, I will be putting it to the test though.. ) I have had 2 good dry-hopped ipas since my issues. Brewing another today.

 

[stewart194]

When you say "pressure ferment", what are you talking about exactly? I have never force carbonated any of my beers by using 30 psi for a few days....I only set it at 10 psi serving pressure and let it ride for 10 days or so before drinking. Is that what you are talking about?

And how would you transfer in a completely enclosed setup? That sounds interesting also.

Thanks!

 

[grathan]

mainly this thread right here:
https://www.homebrewtalk.com/f13/closed-system-pressurized-fermentation-technique-44344/

It allows for natural carbonation from the fermentation process. Also allows for fermenting at warmer temperatures ( I have been forbidden from adding another chest freezer to the collection which is also part of my motivation ).

Transfer on an enclosed setup would mainly be pushing beer out of fermenter with co2 into a fully purged keg. Mainly the fully purged keg in this instance means filled with starsan solution and pushed out with co2.

 

[NHMikeT]

Glad this is still going, there are definitely some great articles posted here. Just to update from a month ago, my latest IPA unfortunately still produced some of the same flavors that have been discussed here - albeit to a much lesser extent, and I believe it was the hops used for dry-hopping (there are other flaws in the beer though, due to the mash i think). The beer is still very drinkable, and I'm really the only person that notices the flaws, but it's still frustrating!

This was my first attempt at keg-hopping using the dryhopper from Stainless Brewing and as I was dumping in 2oz whole Centennial to go along with 1oz Citra, I noticed that they smelled like Easy-Mac powdered cheese...completely oxidized. This was very disappointing since I'd specifically purchased small amounts expecting they'd stay fresher (I don't own a vacuum sealer). So I dumped out all the hops and tried to retain as much Citra as I could, and added 1oz whole Cascade instead (they smelled great), but I don't think I got out all the Centennials... probably would've been better to skip the dry-hop altogether.

Anyway, the beer still pours with great aroma but about halfway through you can start to smell/taste the musty-ness. However, there are other flaws in the beer that I'm pretty confident are due to higher than desired mash pH/astringency. My LHBS was out of acid malt and they mentioned that honey malt has some acidity to it (it did smell a little sour), so I tried that.

(NOTE: I also have a keg of BierMuncher's Centennial Blonde right now, it does not have the same off-flavor, but does also have the astringency so I obviously need to fix the mash pH issue.)

My plan for my next batch is to brew a well-known recipe (e.g, Tim Brewz's IRA) with 2% acid malt, RO water and CaCl2, per AJ Delange's water PRIMER, skip the dry-hop and see how it comes out. I only get (what I presume is) the oxidation off-flavor in dry-hopped beers and this last beer tasted really really good in the FG sample, so this next step should at least let me see if that's the problem.

 

[WNCBrewman]

That seem similar to those in the thread. I have strictly bottled. I've done six to seven batches and 2 had this taste that's hard to describe. Great at bottling time. Week into carbonating, the off flavor came hard and got worse. I've cold crashed both. One was extract, the other all grain brew in bag. Different hops used on dry hop. One w a s centennial, the other cascade. One was only in primary, the other used a second vessel to clear. Both dry hops were added when primary was fully finished. Both times I added cold hops straight from freezer to the vessel. Both were pellet hops. I've dry hopped in past and got fabulous results, other times not so in your face. One great one comes to mind is a citra smash, and the other northern brewers all grain Chinook ipa. The bad one was northern brewer all grain dead ringer and an extract cascade smash. I've got two in the primary now and I'm researching like mad to ensure this oxidation type or diceytl flavor that has cropped up here and there doesn't happen. I'm leaning towards the cold crashing, timing of the dry hop, or the addition of the hops directly from the freezer. Fingers crossed. I'm not happy about not crashing. That really helps clear things up. Maybe like what was mentioned earlier, maybe light drop to 50? Or 10 degrees per day? Also I have cold crashed for about 5 days total to get temp of the volume down to 35. Hope someone nails this thing.

 

[jbaysurfer]

Am I the only one who reads this thread and reads over and over "I'm having the same problems....(insert NOT the same problem here)".

O2 is indeed a common problem in brew process, but "vegetal", "crushed aspirin", are generally not O2 problems. Also, I read one person say "diacetyl doesn't always present itself as a butter bomb"..but the fact is...the vast majority of time it does present as "butter" "fake butter" "butterscotch" or "buttered popcorn" It's probably not productive to assume you have a unique presentation of a common off flavor, because you're going to waste time solving the wrong problem.

I've heard problems that sound like DMS, Diacetyl, Old UV/O2 affected hops, and Oxidation. All different problems with different solutions. It's like this thread has become the holy grail for that one sure solution to what amounts to countless variations of homebrewer problems. So "aspirin", I suggest you check your water/mash PH. Or your cleaning products/water chemistry if what you're describing is more "medicinal" then "crushed aspirin".

"Vegetal", I suggest you check your hop freshness and make sure you do 90 minute boils if you're using Pilsner malt. Pay attention to the source you buy hops from too. Not all homebrew stores take good care of their hops.

"Stale/rubbery/wet cardboard or Cola" I suggest you pay attention to O2 issues. You can cold crash in a carboy by simply putting a #0 stopper into your bung before cold crashing. I then usually point a cO2 hose right at the bung as I slowly remove the stopper. The suction will pull the cO2 into your carboy instead of the surrounding air. If all else fails, cold crash in a keg and when you're done, jump the beer to a 2nd keg. Avoid unnecessary beer transfers as each transfer is one more chance for O2 to get into your beer.

 

[grathan]

Another oxidized IPA for me. Wet cardboard at exactly 1 month from brew date. I am extremely attentive to oxidation issues.

There was a large amount of hops used. All Centennial, 30 minutes on was all from a freshly opened pound of 2014 pellets.
fwh was 2oz
boil was 1 oz
45 min 1 oz
30 min 2 oz
15 min 2oz
5 min 3 oz
0 min 3 oz

dry hop 3oz ( added at high kreusen in primary)


I purged the receiving keg to 30 psi maybe 15 times, the feed hose almost froze up and was completely frosted on the outside. The only slip-up was when racking I put a stainless mesh tube around the racking cane that instantly plugged with loose hops and drew air down from the top (maybe halfway up a carboy) for a couple seconds.


I wonder if I purged well enough. It was a 3-4 gallon beer so quite a bit of headspace in the receiving keg. After reading this thread on another forum, I plan to change my keg purge process.
http://discussions.probrewer.com/showthread.php?36835-Purging-BBT-s

I know they are dealing with hectoliter sized tanks, but interesting that breweries are leaving the gas on overnight to purge the brite tank.

 

[Hermit]

Another oxidized IPA for me. Wet cardboard at exactly 1 month from brew date. I am extremely attentive to oxidation issues.

There was a large amount of hops used. All Centennial, 30 minutes on was all from a freshly opened pound of 2014 pellets.
fwh was 2oz
boil was 1 oz
45 min 1 oz
30 min 2 oz
15 min 2oz
5 min 3 oz
0 min 3 oz

dry hop 3oz ( added at high kreusen in primary)


I purged the receiving keg to 30 psi maybe 15 times, the feed hose almost froze up and was completely frosted on the outside. The only slip-up was when racking I put a stainless mesh tube around the racking cane that instantly plugged with loose hops and drew air down from the top (maybe halfway up a carboy) for a couple seconds.


I wonder if I purged well enough. It was a 3-4 gallon beer so quite a bit of headspace in the receiving keg. After reading this thread on another forum, I plan to change my keg purge process.
http://discussions.probrewer.com/showthread.php?36835-Purging-BBT-s

I know they are dealing with hectoliter sized tanks, but interesting that breweries are leaving the gas on overnight to purge the brite tank.

I rack to a bottling bucket after cold crashing. Cold liquid holds gases better than warm ones yet I've had no oxidation problems.

 

[moment]

This post has become a catch all but I like it. I too am having issues with IPAs. I really only brew them but have a consistent off flavor. I stubbornly want to solve it and have tried a lot of things.

I was sure it was extract twang and made the switch to all grain and I am still noticing it. I was then convinced it was my water, so I did a lot of reading up on water and started using Bru'N'Water to make the appropriate salt / lactic acid additions. I do not have a Ph meter so I am not sure what my Ph is after additions, so that might be a next step.

The flavor I have been getting is caramel / styrofoam and dull. I would think maybe oxidation, but I feel I am pretty good about transferring. I only dry hop in primary and transfer to a bottling bucket and bottle with a wand. I have noticed it takes me a couple pumps with my auto syphon to get it going, anyone else have this issue? Or is this normal?

I also use dextrose boiled in water to carbonate my beer. Not sure if there is anything here.

One thing I need to change is I do not use yeast starters. I have also not seen this talked about in this thread. Almost all of my beers are over 1.060 SG. I have read that under pitching results in a fruity / alcohol flavor and that is not what I am getting, but I will be doing a starter to see if that helps with my issue, but I know it will only improve my beer.

I don't think it is hops, I purchase 1oz packs of hopunion hops from my LHBS and I don't agree that this is related to strains as a lot of commercial beers I like use some of the strains being called out in this thread and they taste great.

Any suggestions? Thoughts? I think I might have more water work / yeast starters to test with, but is what I am describing seem like these could solve my issue?

 

[EarlyAmateurZymurgist]

Another oxidized IPA for me. Wet cardboard at exactly 1 month from brew date. I am extremely attentive to oxidation issues.

There was a large amount of hops used. All Centennial, 30 minutes on was all from a freshly opened pound of 2014 pellets.
fwh was 2oz
boil was 1 oz
45 min 1 oz
30 min 2 oz
15 min 2oz
5 min 3 oz
0 min 3 oz

dry hop 3oz ( added at high kreusen in primary)


I purged the receiving keg to 30 psi maybe 15 times, the feed hose almost froze up and was completely frosted on the outside. The only slip-up was when racking I put a stainless mesh tube around the racking cane that instantly plugged with loose hops and drew air down from the top (maybe halfway up a carboy) for a couple seconds.


I wonder if I purged well enough. It was a 3-4 gallon beer so quite a bit of headspace in the receiving keg. After reading this thread on another forum, I plan to change my keg purge process.
http://discussions.probrewer.com/showthread.php?36835-Purging-BBT-s

I know they are dealing with hectoliter sized tanks, but interesting that breweries are leaving the gas on overnight to purge the brite tank.

Eliminating post-fermentation oxygen exposure does not eliminate wet cardboard because wet cardboard is a hot-side phenomenon. The compound responsible for wet cardboard is called trans-2-nonenal. The precursors (hydroperoxides) for this compound are formed in the mash by via enzymatic oxidation of linoleic acid and linolenic acid by an enzyme called lipoxygenase (LOX-1 and LOX-2). Lipoxygenase is activated 50C (122F) and denatured at 70C (158F). Linoleic acid and linolenic acid are polyunsaturated omega fatty acids (a.k.a. lipids).

What is your mashing process? What is you mash pH? Do you stir the heck out of your mash during mash-in? If you batch sparge, do you stir your mash vigorously when infusing hot liquor? Is your cast-out wort splashed into your kettle? If you use a pump to transfer your cast-out wort to your kettle, do you experience cavitation? Remember, the precursors to trans-2-nonenal are formed on the hot side of the brewing process. Roughing handling of the mash and wort during the temperature range at which lipoxygenase is active increases the likelihood of developing the hyrdoperoxides from which trans-2-nonenal is formed because these substances are formed by lipoxygenase inserting molecular O2 into polyunsaturated fatty acids.

 

[Hermit]

Eliminating post-fermentation oxygen exposure does not eliminate wet cardboard because wet cardboard is a hot-side phenomenon. The compound responsible for wet cardboard is called trans-2-nonenal. The precursors (hydroperoxides) for this compound are formed in the mash by via enzymatic oxidation of linoleic acid and linolenic acid by an enzyme called lipoxygenase (LOX-1 and LOX-2). Lipoxygenase is activated 50C (122F) and denatured at 70C (158F). Linoleic acid and linolenic acid are polyunsaturated omega fatty acids (a.k.a. lipids).

What is your mashing process? What is you mash pH? Do you stir the heck out of your mash during mash-in? If you batch sparge, do you stir your mash vigorously when infusing hot liquor? Is your cast-out wort splashed into your kettle? If you use a pump to transfer your cast-out wort to your kettle, do you experience cavitation? Remember, the precursors to trans-2-nonenal are formed on the hot side of the brewing process. Roughing handling of the mash and wort during the temperature range at which lipoxygenase is active increases the likelihood of developing the hyrdoperoxides from which trans-2-nonenal is formed because these substances are formed by lipoxygenase inserting molecular O2 into polyunsaturated fatty acids.

Last I heard hot side aeration was a myth and I was roundly criticized for suggesting someone look into it even though they had the classic symptoms.

 

[EarlyAmateurZymurgist]

Last I heard hot side aeration was a myth and I was roundly criticized for suggesting someone look into it even though they had the classic symptoms.

Hot-side phenomena are only a myth in the make believe world of amateur brewing where brewing science magically no longer applies. For example, it is commonly believed on this site that racking to a secondary fermentation vessel after primary fermentation is complete will oxidize one's beer. Proponents of this myth demonstrate that they lack even the most fundamental understanding of yeast cell biology. As long as there are yeast cells in suspension, the risk of oxidizing one's beer while racking to a secondary fermentation vessel the way that the average amateur brewer does it is close to nil because the yeast cells that are still in suspension will rapidly scrub any oxygen that is introduced during racking. The point where post-fermentation oxygen exposure becomes a problem is after filtering.

 

[tagz]

I'm pretty sure armature brewing isn't a make believe world... :/

You may have a decent amount of knowledge EAZ but you always come across extremely condesending. You're not likely to win many converts by calling everyone idiots.

 

[Quaffman]

I think my hoppy beers are lacking the crisp hop flavor I'm looking for due to mash ph issues. Finally got my ph meter, so I'll find out soon. All of my dark hoppy beers have the flavor i desire from the hops, but my light beers are lacking it. I think it's from the dark grains bringing the mash ph into the desired range. I'm really excited to try it or and see how it goes. My only question is how much 10% phosphoric acid to add. Would it be in the 1 - 5 ml range, or smaller increments like .1-.5 ml range?

 

[EarlyAmateurZymurgist]

You're not likely to win many converts by calling everyone idiots.

I have never called anyone an idiot, and I am not looking for disciples.

 

[EarlyAmateurZymurgist]

My only question is how much 10% phosphoric acid to add. Would it be in the 1 - 5 ml range, or smaller increments like .1-.5 ml range?

If you have a set of test results for your water supply, Bru'n Water water will get you close to the mark; otherwise, you will have to titrate your water supply to determine it's buffering capacity.

 

[Pelican521]

Ran into this thread last night and read it all. Sounds like exactly what's going on with my IPAs. My brewing techniques are pretty solid, i.e. healthy yeast starters, proper pitching temps, temp control ferm, excellent sanitation, etc.

So my IPAs would taste excellent at bottling time but after 3 weeks of priming, they would already be on their way downhill. After a few more weeks, not very drinkable.

Also, my IPAs were getting MUCH darker over time after being bottled. They would go from a nice pale straw color to an amber or even brown ale color, and even the yeast sediment on the bottom would pour out very dark brown. It would look like 2 completely different beers. At bottling time, they taste great. This last one I brewed went from a delicious tropical flavor to an earthy, muddy, almost a sherry flavored mess, and ended up tasting like all the other IPA I'm made regardless of what variety of hops I used.

I was just about to pull the trigger on getting a kegging system but after reading this post, it looks like that won't be the magic solve.

I've used tap water for them after getting my water report emailed me from my water supplier and tried all sort of additions building a water profile in EZ water to match an IPA profile. Nothing worked.

I'm thinking is it's oxidation from my dry hopping along with some messed up PH issues (I do partial mashes) with my attempt of building a water profile with my tap water that I can't be completely sure is accurate based on an emailed water report. I'm going to try my recipe again and try these tweaks to see if it makes it any better...

1 - Change my water from tap to Poland Spring bottled water-at least I know what I'm starting off with and is pretty soft.
2 - Again, skip the secondary
3 - Skip all my water additions, except for maybe a tsp of Gypsum
4 - Skip the dry hopping, like I said, my beer tasted delicious at bottling time and very hop forward. Just wished it stayed that way, so keeping it simple without the DH can rule out oxidation from the DH stage.
5 - Lastly, skip the cold crashing, I've read that it introduces O2 into your beer so I'll skip it to see it it helps.

I don't have a Co2 tank so I can't purge anything. Still probably will get a kegging system as I'm getting sick of bottling, but that will be down the road.

Right now I have a chocolate oatmeal stout fermenting, once that finishes up I'll try out my IPA again with these changes...

Any thoughts?

 

[Yooper]

First, it's not uncommon for IPAs to already lose hops flavor and aroma at three weeks after packaging. That's the nature of the beast, and why IPAs are generally best when fresh.

However, it does sound like you have some oxidation issues (darkening is a classic sign, as is some muddling and loss of flavor). Sherry flavor is also a big oxidation flag.

Of course, darkening can happen when yeast flocculates as well, as yeast is white and will lighten the beer quite a bit when in suspension, so I assume you are talking about an already clear beer turning darker with time.

First, I think you are on the right track to skip building any sort of 'profile' for the water. You may want to increase the sulfate level in an IPA, but that's about it. You want a mash pH of 5.4 or so, for best hops expression and flavor. Some brewers like a sulfate level of up to 300 ppm in IPAs and APAs, but for most of my IPAs, I like about 150 ppm of sulfate. As long as your mash pH is in target, you can start with 125-150 ppm of sulfate and skip other additions.

I don't cold crash (I keg), but I can't see how that can cause an issue with oxidation.

One thing I didn't see you mention is the length of time. If you're leaving the beer in the primary for a long time, then using a secondary, and then cold crashing after dryhopping, that right there could explain the loss of hops flavor and aroma. I am kegging a hoppy APA today that has been dryhopped. The beer was brewed on 7/31. I will be drinking it starting this weekend. I know it's faster than bottling, as you have to wait for it to carb up, but as it ages (especially at room temperature), hops flavor and aroma will fade fairly quickly.

 

[Francis]

My last 2 IPA brews have been MUCH better than previous attempts. That "off flavor" has not made an appearance. Kegging has helped as well as skipping secondary and dry hopping in a well purged keg. I do cold crash, it's hard not too when you don't secondary. Both IPA's were session beers so we'll see if that holds true for something bigger. Figured I would start small and work my way up.


Sent from my iPhone using Home Brew

 

[Pelican521]

Thanks again for your responses Yooper (and Francis). Yooper, you have commented on my before and after pics of one of my IPAs in a separate post saying they look like two completely beers

As far as time goes, for this latest IPA I skipped the secondary and did a 2 week primary then I dry hopped for a week with 2 dry hop additions (after day 3 of my first DH addition I added the second addition for a total of 7 days). I tried to be careful not to disturb the Co2 layer, if any, when I did my DHing. I packaged right after.

I wouldn't say that the hop/flavor is fading over time but more being replaced by the muddy, earthy, slight sherry flavor once they are finally carbed up and ready to drink (say 2-3 weeks and getting worse as time goes on).

They've been bottled about 8 weeks and are on the borderline of being un-drinkable.

Not sure how valid my comment on the cold crashing and oxidation is, but it is something I just read about in my quest for knowledge. I believe it was quoted from someone from a brewery saying when cold crashing, the beer will absorb any oxygen in the headspace of your carboy or something. Again, just something I read, but I figure it's not something that I really need to do so I would just skip it the next time.

Also, could leaving them out at room temp cause any issues (after carbed up)?

 

[mbbransc]

YES!! For IPAs, you want to keep them cold. Warm beer ages faster. Once the bottles are carbed up, throw them all in the fridge.


Sent from my iPhone using Home Brew

 

[grathan]

I had some bad luck with cold crashing. I've talked about it a little in this thread.

In addition to skipping the cold crash I would look at making a kit recipe like Pliny from Northern Brewer. This would eliminate recipe from the equation as well.

 

[ocluke]

I'm a little late to the party, but this thread came up in a recent search and the first thing I thought of was oxidation. It could be simply a matter of using oxidized hops (you mentioned that they were old), or it could be during transfer as you also suggested. I'd be interested to hear if you were able to fix your issue, and what the root cause was. If it helps, here's my method for avoiding oxygen while kegging (CO2 transfer process).

 

[gifty74]

I also have many of the off flavors described in this thread (although I now know there could be several different issues going on here), but I recently got results back from a local homebrew competition. Two master judges both gave my Tripel a 19/50 (the worst I ever got). Their underlying comment was "oxidation", and lack of flavor, and no malt backbone. This beer was bottled, and they tasted it right at the 3 week point after bottling. Didn't have an excessive aging time or anything like that. Up until now I have recirculated during the mash as I have a direct fire system. The probe in my pump gives me my mash temp, so I need to recirculate to get an accurate reading. Then my flame kicks on whenever directed by the temp controller (if the temp drops too low). I don't think I've seen one brewery (at any level) recirculate during the mash. I'm wondering if this might be pushing the limits of aeration on the 'hot side', and making aeration an actual possibility. Because the outlet of the pump is limited by a ball valve that is maybe a quarter open, the March pump is still running at full speed, introducing the wort constantly to air/oxygen. On top of that it's being pumped in the top of the mash tun, and splashed down on top of the grain bed. I just wonder how detrimental the pump running is as it is churning the wort the head due to running at full speed but only letting a low flow rate out of the pump. Any thoughts here? How else could I have gotten such high oxidation comments on a 3 week old beer?

 

[Horseshoot]

"I don't think I've seen one brewery (at any level) recirculate during the mash."

Wait... What? Loads of brewers recirculate during the mash. Including me.

 

[gbx]

I also have many of the off flavors described in this thread (although I now know there could be several different issues going on here), but I recently got results back from a local homebrew competition. Two master judges both gave my Tripel a 19/50 (the worst I ever got). Their underlying comment was "oxidation", and lack of flavor, and no malt backbone. This beer was bottled, and they tasted it right at the 3 week point after bottling. Didn't have an excessive aging time or anything like that. Up until now I have recirculated during the mash as I have a direct fire system. The probe in my pump gives me my mash temp, so I need to recirculate to get an accurate reading. Then my flame kicks on whenever directed by the temp controller (if the temp drops too low). I don't think I've seen one brewery (at any level) recirculate during the mash. I'm wondering if this might be pushing the limits of aeration on the 'hot side', and making aeration an actual possibility. Because the outlet of the pump is limited by a ball valve that is maybe a quarter open, the March pump is still running at full speed, introducing the wort constantly to air/oxygen. On top of that it's being pumped in the top of the mash tun, and splashed down on top of the grain bed. I just wonder how detrimental the pump running is as it is churning the wort the head due to running at full speed but only letting a low flow rate out of the pump. Any thoughts here? How else could I have gotten such high oxidation comments on a 3 week old beer?

Some judges are very sensitive to oxidation especially in light coloured beers. (and often its only one judge who then mentions it to other judges and the suggestion makes others "taste" it too) As there is no such thing as hot side aeration I'd guess its a packaging error. How do you bottle? Do you rack to a unpurged bottling bucket, stir in a priming solution and then pour into bottles?