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What is causing this off flavor?

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Microphobik

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I have been having a persistent off flavor in many of my beers and I could use some thoughts on what is causing it. It's a very subtle stale, fruity, almost dishrag like flavor. its very subtle. The beer is still drinkable but it's bumming me out. It seems to only happen with my kegged beer but it only comes on after a few weeks. For example, right now I have a best bitter on tap. For the first week or two it was great. Very clean. But after a week or two I started to notice the esters getting a fruity, almost honey taste, that wasn't all that nice and had a subtle undertone that I can only describe as a dish rag. It gets stronger and stronger as the beer ages, and seems to be much stronger on the first beer poured than in those that follow. Though it is still present in those as well. I've had this before but probably never so noticeably as I normally brew darker beers. I have never noticed this in my bottle conditioned beers though.

Is this oxygenation, or a sanitary issue. I'm diligent with cleaning. I use PBW on everything before kegging, followed by star san. If it is a cleanliness issue I'm at a loss for how to improve things. My thinking so far is that maybe I'm somehow oxygenating things as I move to keg. But again, I don't know what to do differently.

Anyone ever have something like this happen or know what it might be?
 

ol-hazza

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Could it be your beer lines? Never had it myself but have read about it somewhere
 

Bellybuster

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When was the last time you tore apart your taps? Seeing as the first pour is the strongest, suggest something in the serving side of the keg.
Taps can build up some nasty crud.
 

MannyEdwards

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Dishrags smell the way they do because of mold and mildew, which love to grow on plastic. Try boiling or replacing your tap lines.
 

Yooper

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It sounds like a classic description of oxidation. It will first start to taste a bit stale, and pick up "sherry" or "brandy" notes which are a bit sweet. It's nice in a big barleywine, but not in other beers.
 

brick_haus

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I agree with Yooper. Have you seen any color changes along with the off flavors?
 

ricshayne

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I get the same thing on my IPAs but nothing else. I'm pretty sure its oxidation as the flavors become exactly as you said, and the color turns from, on my last IPA, a beautiful golden yellow, into a dark, murky, swamp water color.
Not trying to hijack the thread but does anyone have any ideas how to avoid this?
 

tooldudetool

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I agree, dirty tap lines or oxidation. This happens to me with my super hoppy beers over time. Be diligent about purging the keg with co2 before racking, and even purge your racking cane and tubing before transferring. Purge the fermenter after any dry hop additions, or dry hop while there is still some yeast activity. Once racked, purge the keg headspace several times again before force carbonating... Following these steps has greatly increased the time that my hoppy beers stay "fresh".
 

mkirkland

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I purge my keg once cleaned and ready to use. Then i attach my BEER ball lock to my racking cane. I open the purge valve on the keg and then start the siphon. Now i know there is NO oxygen in my keg and also never give the beer a chance to splash around even if there was some oxygen in the keg. I just fill from the bottom up and the co2 purges itself from the purge valve. Then i close the purge valve and carb to my desired level.
 
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Microphobik

Microphobik

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Thanks everyone. I recently replaced all the lines and the taps are brand new. This is my first use of the taps (forward sealing flow control perlicks). But i was getting it before the changes as well as after. My hunch is oxidation like many have pointed out. I don't purge the kegs before adding the beer. I realize this increases exposure but I assumed it wouldn't be that significant. Is that my mistake? I always purge after filling them, just not before. But to be totally honest, I forgot to do it on this one until about 8 hours after putting the beer on the C02, and this is the worst example of that flavor that I've had.

Can someone explain the best way to purge the keg with C02? I assumed that if I just fill it with C02 and burb the keg a few times then I would lose 90% of the c02 once I opened it to get the beer in, despite any blanketing effect. Or am I assuming wrong?

Or is there a way to get the beer from my siphon into the keg through the disconnect when it's just gravity fed? I had assumed not, but is that what you're saying mkirkland?
 

mkirkland

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Or is there a way to get the beer from my siphon into the keg through the disconnect when it's just gravity fed? I had assumed not, but is that what you're saying mkirkland?
Yea thats what i did. I used the black (beer out) oand connected that to my out of the siphon, strait into the keg. Now this point i was going 2.5gal kegs. So maybe wouldnt work in a 5gal keg without co2 force.
 

pdxal

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Another possible option to reduce oxygenation in the keg is to add priming sugar and condition in the keg like you would in the bottle before hooking up CO2. The first pint will have trub, though. The yeast will eat up the additional oxygen as they carbonate in the keg. Some brewers do this in their bottles, too, to prolong shelf life.
 

ol-hazza

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Thanks everyone. I recently replaced all the lines and the taps are brand new. This is my first use of the taps (forward sealing flow control perlicks). But i was getting it before the changes as well as after. My hunch is oxidation like many have pointed out. I don't purge the kegs before adding the beer. I realize this increases exposure but I assumed it wouldn't be that significant. Is that my mistake? I always purge after filling them, just not before. But to be totally honest, I forgot to do it on this one until about 8 hours after putting the beer on the C02, and this is the worst example of that flavor that I've had.

Can someone explain the best way to purge the keg with C02? I assumed that if I just fill it with C02 and burb the keg a few times then I would lose 90% of the c02 once I opened it to get the beer in, despite any blanketing effect. Or am I assuming wrong?

Or is there a way to get the beer from my siphon into the keg through the disconnect when it's just gravity fed? I had assumed not, but is that what you're saying mkirkland?
The best way would be to fill it with star san and the push that through with co2.

I think thats a bit wasteful though so i like to pour in a couple of pints of star san, pressurise and purge 4-5 times, push star san through beer line with co2 and then purge, lift the lid and run the beer in through some beer line that runs to the bottom of the keg. Ideally i would run it in through the beer out post with the quick release open but im not set up for that yet. I then purge the headspace a couple of times. No problems with oxygen yet but im not many batches into kegging.
 

snail

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I've been having the same problem with off flavors. Beer will taste great before kegging and will eventually get the sherry, fruity flavor and turn a lot darker. I looked through various forums for weeks and all signs pointed to oxidation. I am extremely careful transferring beer (closed transfer w/co2) and purge everything so I couldn't accept it was oxidation causing the problem. I decided to disassemble every piece of equipment and clean it. I found in my co2 quick disconnect a bunch of black residue, assuming it was mold or something. Beer must have backed up into it a long time ago and I never noticed. It makes sense that the off flavor/appearance appeared 1-2 weeks after I kegged it. Anyway, I replaced the tubing/quick disconnect and haven't been able to brew since, but am hoping that fixed it. Might be something to look at......
 

h22lude

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I've been having the same problem with off flavors. Beer will taste great before kegging and will eventually get the sherry, fruity flavor and turn a lot darker. I looked through various forums for weeks and all signs pointed to oxidation. I am extremely careful transferring beer (closed transfer w/co2) and purge everything so I couldn't accept it was oxidation causing the problem. I decided to disassemble every piece of equipment and clean it. I found in my co2 quick disconnect a bunch of black residue, assuming it was mold or something. Beer must have backed up into it a long time ago and I never noticed. It makes sense that the off flavor/appearance appeared 1-2 weeks after I kegged it. Anyway, I replaced the tubing/quick disconnect and haven't been able to brew since, but am hoping that fixed it. Might be something to look at......
Bringing back an old thread. Did you ever brew after and did the co2 disconnect fix your issue? I've been having the same problem. My beer tasted really good a week in the keg but 2 to 3 weeks I get this off flavor and can't put my finger on it. I keep cleaning all beer parts and nothing helps. I will need to check my gas disconnects now.
 
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Microphobik

Microphobik

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Bringing back an old thread. Did you ever brew after and did the co2 disconnect fix your issue? I've been having the same problem. My beer tasted really good a week in the keg but 2 to 3 weeks I get this off flavor and can't put my finger on it. I keep cleaning all beer parts and nothing helps. I will need to check my gas disconnects now.
While the question wasn't for me, I've come to the conclusion in my case that the off flavor I was experiencing is actually yeast slowly settling out in the keg, and perhaps I am just sensitive to it and don't care for it. It's the only thing that makes sense to me given the consistent good/bad/good again thing I am experiencing over and over. And it is always solved by bottling and letting it sit at warm temps for a few days. But I'm not experiencing any change of color or other oxidation issue. Have you tried bottling any of your beers off the keg to see how they taste? If they improve then that likely rules out oxidation or contamination. If they get worse it would seem to point to it.
 

h22lude

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While the question wasn't for me, I've come to the conclusion in my case that the off flavor I was experiencing is actually yeast slowly settling out in the keg, and perhaps I am just sensitive to it and don't care for it. It's the only thing that makes sense to me given the consistent good/bad/good again thing I am experiencing over and over. And it is always solved by bottling and letting it sit at warm temps for a few days. But I'm not experiencing any change of color or other oxidation issue. Have you tried bottling any of your beers off the keg to see how they taste? If they improve then that likely rules out oxidation or contamination. If they get worse it would seem to point to it.
If you are having a weird reaction to yeast wouldn't you think you would taste it no matter if it was kegged, bottled from a keg or bottled and carbed? I would think if you have a weird taste with yeast you would get the same thing from bottle conditioned commercial beers too. Unless you get a weird taste to specific yeast strains.

My next batch (which I hope to brew next Thursday) will be Yooper's Fizzy Yellow Beer. I'm hoping since it is a lighter beer I will be able to taste any off flavor. What I plan on doing is using my tap water but letting it sit out overnight to let any chlorine dissipate. I'll also use half a campden tablet just in case. All my brewing equipment has been cleaned really well. I may even boil water and run it through my pump, lines and CFC before brewing. I'll be adding calcium chloride and lactic acid to bring my water and mash pH in line to what it should be for this lighter colored beer. This should produce a clean beer.

I will be calibrating my temp controller to make sure it is reading correctly so I know I'm not fermenting hot. I'll ferment in my plastic bucket. I tried to use my bucket to do a closed system transfer but it didn't work too well but I will be purging my keg using starsan (or maybe switch to iodopher) and pushing it out with CO2 so I eliminate as much O2 as possible. I will keg half and bottle half.

This will test a few things. If both bottles and kegs taste good, that means I fixed the problem with my water adjustments and cleaning of my set up. If the bottles and kegs both have an off flavor, the only variable left is my bucket which I would then replace and hopefully that fixes things. If my kegged beer has an off flavor but the bottles don't, it is my kegging system. If the bottles have an off flavor but my keg doesn't, I have no clue what to think about that lol
 
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Microphobik

Microphobik

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My thinking is that when whatever yeast is still in suspension is dispersed fairly evenly, I don't really taste it. But after about a week or so of cold conditioning the stubborn stuff starts to fall out and I get a high concentration of stuff I don't like down at the bottom of the keg and right into my glass. But when I bottle I pour off the top, and possibly speed up a few other chemical reactions and their is no yeast concentration. It's just my best guess. It's a consistent problem, that always comes on and then goes away. It seems to be less pronounced with hoppy beers. It''s there but goes away faster. It could just be that the hops are covering up the flavor, it could be that something in their oils are binding with whatever is dropping out and pulling it out faster. But again, I'm completely guessing. These are beers that have won awards though. So I'm confident it's not oxidation or contamination. But it's a bit of a mystery. I've come to the conclusion that my ales just need to be lagered before they will be any good :)
 

pdxal

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My thinking is that when whatever yeast is still in suspension is dispersed fairly evenly, I don't really taste it. But after about a week or so of cold conditioning the stubborn stuff starts to fall out and I get a high concentration of stuff I don't like down at the bottom of the keg and right into my glass. But when I bottle I pour off the top, and possibly speed up a few other chemical reactions and their is no yeast concentration. It's just my best guess. It's a consistent problem, that always comes on and then goes away. It seems to be less pronounced with hoppy beers. It''s there but goes away faster. It could just be that the hops are covering up the flavor, it could be that something in their oils are binding with whatever is dropping out and pulling it out faster. But again, I'm completely guessing. These are beers that have won awards though. So I'm confident it's not oxidation or contamination. But it's a bit of a mystery. I've come to the conclusion that my ales just need to be lagered before they will be any good :)
If these beers have won awards the judges must have given you feedback on the off flavor, no?
 
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Microphobik

Microphobik

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It sounds like maybe you missed the earlier part of the thread. The original question was framed around the fact that in virtually all of my beers they start off great, go into the keg and taste good for about a week, and then get terrible (by my estimation) and then good again. I was just wondering what might be causing it. Because the off flavor goes away eventually, especially after bottling, there is no off flavor for the judges to comment on. I was simply referencing the fact that many of these beers have won awards to illustrate that there is no inherent flaw, just something causing a temporary off flavor. My best guess since originally posting many months ago is that it's got something to do with the yeast settling out once kegged. But I really have no idea.
 

pdxal

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Maybe you missed that I posted earlier about 20 hours after you started the thread.;)
Sounds like you need someone else to taste your beers, judges or no, during the time that the beer has the off flavor.
 

Brizzo

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Wrong thread
 
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