Beers get off-flavors after kegging

[Drackean]

Well, I thought I might be able to sort that out myself, but it seems I need help… (slowly taking another sip of a disgusting Irish Red)

I brewed several batches of beer now (over 180 gallons) and have stumbled upon an issue I just can’t understand, which seems to happen to all my “brown” beers lately (Irish Red, Brown Porter, English Brown). The beers usually tastes fantastic 2 weeks after fermentation or so, after which I keg and carbonate at fridge temperature. Sampling is usually fine until about week 2 or 3. Gradually after that time, the overall flavor seems to shift from nice nutty and caramel flavors, low hop aroma, clean or subtle yeast character to some kind of flatness and harshness, and eventually (several months later) to something like acetaldehyde as though the beer had been fermented at 85F.

Strangely enough, I brew consistently great stouts and APA/IPA, although I guess they have the same issue, which is probably only hidden by the heavy roasts or hop character. My fermentation temps are always closely kept in check at 65-68F with an expensive Fluke thermometer and 2 of those crystal-sticker things.

I suppose it is a contamination issue on the cold side by some kind of bug that is able to screw my beers below 4 degree C, but I clean and sanitize everything that comes in contact with my product. My kegs are always disassembled, filled with oxiclean, rinsed with hot water 2 times, then cold water one time, then sanitized before being filled. My lines are cleaned the same way at each keg change. Here’s a summary of my process :

-I put my cleaned immersion chiller 15-20 minutes before the end of the boil, then I carry my kettle in the kitchen, start the chiller and put the lid on (leaving a gap to let steam escape).
-Meanwhile, I rehydrate my dry yeast with boiled water in a sanitized container, with an aluminium foil on it.
-My oxycleaned autosiphon gets sanitized in Starsan and the beer is racked, splashing at the bottom of the carboy to oxygenate.
-The fermented beer goes from primary straight to the keg with the same reoxycleaned and resanitized autosiphon, without splashing this time, of course.

I’m out of solutions. Any thought ?

 

[pdietert]

Could it possibly be oxidation? Here is a good article:

http://www.winning-homebrew.com/acetaldehyde.html

 

[pdietert]

Specifically:

The oxidized or acetic-cider version is produced when ethanol oxidizes, or sometimes from bacterial contamination. It is produced when ethanol is oxidized back to acetaldehyde, and then the acetaldehyde is converted to acetic acid. To prevent this type of off flavors, keep oxygen exposure to a minimum. When transferring your beer, flush the receiving container with CO2, keep the hose below the surface of the beer, keep a lid on top while transferring, make sure all connections are air-tight, etc. These are things you should be doing anyway, but if you are having a problem with acetaldehyde flavors or aromas in your homebrew, oxidation is one of the things to look at.

 

[Drackean]

My oxygenation practices are maybe somewhat deficient, but I doubt I'm doing significantly less than most people who brew great beer. I'm doing something like :

1-Rack from kettle to carboy and intentionally splashing

2-Shake the heck out of it for 5 minutes or so

I use orange carboy caps that are not 100% airtight, but I don't think it is my problem.

 

[pdietert]

Sorry my spell checker corrected my misspelled oxidation to oxygenation. It has been corrected.

 

[Drackean]

Thank you for the link.

I don't flush my kegs with CO2, so it is surely something I could improve in my process, but I can't imagine it to be the cause of the mess I actually have to deal with : if so, everyone would NEED a kegging system to brew a drinkable beer !

BTW, excuse me if what I write probably seems a bit awkward, I suppose you guessed I don't speak english often.

 

[pdietert]

if so, everyone would NEED a kegging system to brew a drinkable beer !

Bottle conditioning is the alternative. Since there is active fermentation during bottle conditioning, it will use up any oxygen introduced during the procedure (to a certain extent). Oxygen absorbing caps also help a bit. You can keg condition which will help with any oxygen introduced during kegging by carbonating with corn sugar. I still would strongly suggest purging head space at the minimum. I also suggest filling the keg with CO2 before racking if you are not keg conditioning. I do it on a pressure setting of 2 - 3 psi so it is not wasting a ton of CO2.

BTW, excuse me if what I write probably seems a bit awkward, I suppose you guessed I don't speak english often.

I did not notice. I am sure that my writing reads foreign sometimes but I am a native English speaker

 

[Yooper]

My oxygenation practices are maybe somewhat deficient, but I doubt I'm doing significantly less than most people who brew great beer. I'm doing something like :

1-Rack from kettle to carboy and intentionally splashing

2-Shake the heck out of it for 5 minutes or so

I use orange carboy caps that are not 100% airtight, but I don't think it is my problem.

Yes, you are doing fine! One thing I noticed- you say that this "flavor" comes very late, after several months. If that is the case, it's simply that the aged beer has oxidized, as "several months" is quite old for a medium/low OG beer. The beer will probably be at its peak at 6-8 weeks old, and then start to taste less great as the beer ages. Oxidation gets worse with age, and flavors fade also. I wonder if what you're perceiving is just the natural aging of beer. Cold storage (as in the kegerator) slows it down, but does not stop ig.

 

[cfonnes]

Carbonic acid?

 

[Drackean]

Bottle conditioning is the alternative. Since there is active fermentation during bottle conditioning, it will use up any oxygen introduced during the procedure (to a certain extent). Oxygen absorbing caps also help a bit. You can keg condition which will help with any oxygen introduced during kegging by carbonating with corn sugar. I still would strongly suggest purging head space at the minimum. I also suggest filling the keg with CO2 before racking if you are not keg conditioning. I do it on a pressure setting of 2 - 3 psi so it is not wasting a ton of CO2.

Clever, I didn't recall that bottle conditioning had this benefit. I do purge headspace after filling, but I never "keg conditioned" or filled an empty keg with gas. I might just try one way or another next time, as you do. But I still doubt it will settle my issue : I am noticing a significant quality drop 2 weeks after kegging, so about 1 month after yeast pitching. That would be a huge load of oxygen pickup.

One thing I noticed- you say that this "flavor" comes very late, after several months. If that is the case, it's simply that the aged beer has oxidized, as "several months" is quite old for a medium/low OG beer.

What I describe as Acetaldehydish is a pretty recent feature of my 5 months old Irish Red, which have been kept in the fridge since early January : that's what I meant by several months. I could live with the fact that my brews have that kind of life span. Unfortunately, as stated above, I seem to notice the beginings of problems after 2 weeks or so in the keg.

I'm actually mourning my barely carbonated 2 weeks old Brown Porter which was downright delicious a few days ago. That can't be normal...

I don't know about carbonic acid.

 

[Drackean]

pdietert : You got me thinking... I did "keg condition" once an amber ale last year and, as I remember it, it didn't have the flaw I am finding in my other brown/red type beers ever since... I might just have to pay attention to oxidation, as you and the article you mentionned say. So I either :

1- Fill the keg all the way up at 2-3 psi, bleed, fill again, bleed, slowly take off the lid and carefully rack from the bottom without moving the keg so much so co2 doesn't escape. You said you don't use that much co2 doing so ?

or

2- Boil a corn sugar solution for about 18 liters of beer, chill it, pour it in the keg and rack on it. How do I account for headspace ? I suppose a spunding valve would be handy at that point ? I often read people talking about the less clean finish of a natural carbonation, could that be an issue ? I haven't bottle conditioned for so long now...

 

[pdietert]

1- Fill the keg all the way up at 2-3 psi, bleed, fill again, bleed, slowly take off the lid and carefully rack from the bottom without moving the keg so much so co2 doesn't escape. You said you don't use that much co2 doing so ?

I do it a little different. I fill the keg up with sanitizing solution (StarSan diluted to the recommended amount) and cap/seal the keg. After a few minutes, I invert the keg and rest for a few more (this also helps to find any leaks). Then I turn it back upright and drain the keg by either by piggy backing to another keg (couple between liquid out and liquid out, pressurize through gas in of the full keg and purge the gas side of the empty keg) or into a bucket. I set the regulator to the lowest setting that will still transfer the sanitizer. This also fills the sanitized keg with CO2. There still may be a little air at the top depending on the length of your gas dip tube (oxygen is lighter than CO2 and will settle on top of it) but I do not worry about it. When you rack to the keg and it is filled from the bottom, it will push the air out of the keg through the lid opening. The only thing that gets mixed in with the beer is CO2. When it is full and before moving the keg I cap and then purge the head space 4 times (sometimes I have to jack up the pressure to get the lid to seal).

2- Boil a corn sugar solution for about 18 liters of beer, chill it, pour it in the keg and rack on it. How do I account for headspace ? I suppose a spunding valve would be handy at that point ? I often read people talking about the less clean finish of a natural carbonation, could that be an issue ? I haven't bottle conditioned for so long now...

Priming for kegs is different than priming for bottles, I believe it is 1/2 the ammount sugar that is used but you should verify that and I would still purge the air in the head space. The only times I have primed a keg with sugar (it has been awhile) was when I had a small 5 lb CO2 tank and did not want waste it.

I think it is a matter of taste on the carbonation methods, some people swear by bottle conditioning. Some of the best rated beers in the world are bottle conditioned. If I am going to age a beer longer than 1 year, I bottle condition. I have never aged a beer longer 8 months in a keg.

Also on the Irish Red, 5 months, is a fairly long time, especially for beer that has not been pasteurized and/or prepared for retail sale. The only home brew that I have that lasted that long (kegged or bottled), have been the ones that I have purposely aged and are beers where oxidation is not as apparent and/or is desired (old ale, scotch ale, Belgian dark strong). But lighter bodied, lower ABV beers really do not last too long.

The other beers that you refer to that have started to turn in 2 to 3 weeks sound like they are oxidized. Oxidation does not become apparent for some time, though I think 2 weeks is pretty short, but it does not seem too far off. After you keg do you store it? Is the 2 to 3 weeks that your refer to the time that it has been tapped or the time since it was kegged?

 

[pdietert]

Another thought, when was the last time you cleaned your beer lines? Try pouring a glass then immediately pour another then compare them (I would taste the second one first). Do you notice a difference? If you have a clean picnic line and tap, you can pour one with that and compare.

 

[Drackean]

Thank you for your help.

The other beers that you refer to that have started to turn in 2 to 3 weeks sound like they are oxidized. Oxidation does not become apparent for some time, though I think 2 weeks is pretty short, but it does not seem too far off. After you keg do you store it? Is the 2 to 3 weeks that your refer to the time that it has been tapped or the time since it was kegged?

2 to 3 weeks is the time after it has been racked to a keg and put in the fridge. The beer is still drinkable at this point, but you start to feel nice malt flavors are fading to something "flat tasting" and a little harsh.

I clean my lines at each keg change with oxiclean and clear water. I also like to run water out of my faucets and taste to "make sure" the system imparts no off-flavor, though I suppose beer probably can "scrub" and grab some nastiness out of the lines wheras water can't. I do have a unused cobra tap I could use to compare with my main system.

 

[Spartan1979]

Another thought, when was the last time you cleaned your beer lines? Try pouring a glass then immediately pour another then compare them (I would taste the second one first). Do you notice a difference? If you have a clean picnic line and tap, you can pour one with that and compare.

I'm surprised it took this long for this to be suggested.

 

[pdietert]

I'm surprised it took this long for this to be suggested.

Yea, sometimes I start out looking for the most complex solution and forget about the simple ones.

 

[LordUlrich]

Thank you for your help.



2 to 3 weeks is the time after it has been racked to a keg and put in the fridge. The beer is still drinkable at this point, but you start to feel nice malt flavors are fading to something "flat tasting" and a little harsh.

I clean my lines at each keg change with oxiclean and clear water. I also like to run water out of my faucets and taste to "make sure" the system imparts no off-flavor, though I suppose beer probably can "scrub" and grab some nastiness out of the lines wheras water can't. I do have a unused cobra tap I could use to compare with my main system.

This sounds like the problem. Beer lines need to get acid cleaning. Oxyclean won't get rid of beer stone where the bugs like to hide. It takes about two weeks for beer line issues to become noticeable.

 

[Drackean]

This sounds like the problem. Beer lines need to get acid cleaning. Oxyclean won't get rid of beer stone where the bugs like to hide. It takes about two weeks for beer line issues to become noticeable.

If you put it that way, my lines haven't been cleaned with a proper cleaner since I bought new ones last year, which is a while. I'll take care of that, thank you.

As important as it is, however, I don't think this is where the problem I notice comes from : how could it not affect the beer in the first few days, and begin "leaking" more and more as the beer ages ? Pdietert's oxidation theory seems more likely to me...

Could it be an english yeast character I just personally don't like that shows up later when the beer conditions ? The beers we are speaking of have been fermented with Nottingham or Safale-04. I have a 1 week old Safale-05 cream ale (1049 and 18 IBU with about 10% rice flakes) on tap which samples very clean at the moment. I wonder if the same problem will show up.

 

[Drackean]

It takes about two weeks for beer line issues to become noticeable.

Duh ! Didn't read that part. Though I don't understand why it takes so long to become noticeable...

 

[LordUlrich]

Duh ! Didn't read that part. Though I don't understand why it takes so long to become noticeable...

It takes time for the bugs which cause the off flavor to multiply. When you rinse (even with water) a beer line and get rid of the surface soil you reduce the microbe counts, but their are still some hiding in the beerstone. In my experience in about 2 weeks they get enough time to replicate enough to be an issue. Or at least that is how I understand it.

I should add a completely uncleaned line will impart flavor issues right away.

A good cleaning with Starsan should help, or you could just replace the lines. At home I replace my lines yearly. When I maintained a commercial system, I did an acid cleaning every 2 weeks and caustic cleaning every 4 months.

I'd try the picnic tap and see if it fixes things. It could be oxidation, but usually that is more gradual than you describe. At least if it is a beerline issue your keg is still fine.

 

[sabitu]

I had a similar experience and based on your description it sounds like carbonic acid. I had a stout that tasted great before kegging, but after 2 weeks it had a harsh bite and the flavors were bland. The beer developed a sour type of flavor as time went on. I am having the same issue on a stout I just recently kegged.

It's weird because the beer doesn't seem overcarbonated coming out of the tap. With my current stout, I sat it out at room temperature to degas it in an attempt to fix it. I opened up the keg lid at one point and tasted a room temperature sample and it was clearly way overcarbonated. I am still degassing it so hopefully this works. I waited too long with my last stout and the batch was ruined.

To me carbonic acid makes sense because week 2 or 3 is when the beer has fully absorbed all of the CO2 which is the point when the off flavor develops.

What method do you use to carbonate your beer? I found out that my low pressure gauges on my regulator are defective which is what caused my problem.

 

[Drackean]

I force carbonate at about 15 psi.

I have a cream ale on tap which has been in keg for three weeks now, on the line my irish red was. It is light, crisp, clean and tasty. No off flavor as far as I know. Here's the recipe, so you can imagine there is no place for a flaw to hide in such a beer :

8.8 lb 2 Row
1.3 lb Flaked rice

18 IBU
US-05

I'm thinking again, could my "problem" be only an english ester of US-04 ? Reading about it, it may be a spicy/phenol-like flavor I also seem to taste in Nottingham beers.

 

[Near-Beer-Engineer]

What method do you use to carbonate your beer? I found out that my low pressure gauges on my regulator are defective which is what caused my problem.

How did you figure out your gauges were wrong? Also did de-gassing eventually help with that carbonic acid bite?

 

[sabitu]

How did you figure out your gauges were wrong? Also did de-gassing eventually help with that carbonic acid bite?

The face of the gauge was out of alignment which meant the needle would point to the wrong PSI. Unfortunately de-gassing did not fix the beer. It got better and was drinkable, but the intended flavor wasn't there anymore.