Odd off flavor -- thoughts?

[mcduhamel]

I've been brewing for 15 years, and during that entire time, I've almost always detected a certain flavor in beer I keg that I don't see in the same beer if I bottle it. The flavor is very hard to describe: it's almost reminiscent of keg lube (which I know is supposed to be flavorless), vaguely metallic (but not the dreaded copper penny flavor). Sometimes it's quite subtle; other times it hits me over the head. I've detected it in new kegs and used kegs. It shows up whether I force carbonate or keg condition. It appears in almost every style of beer I brew, but is more prominent in pale ales and bitters than it is in saisons and Belgians. I obsessively disassemble my kegs before use, clean with PBW, sanitize with StarSan, and flush with CO2 before transfer. Has anyone else ever experienced anything like this, and does anyone have any thoughts regarding what's going on?

 

[jfrizzell]

What water are you using? Are you filtering? Doing any water adjustments?

 

[GLWIII]

I had a similar problem, although a bit different off flavor, and took the same steps as you. I finally changed my keg line and that solved the problem right on the spot. Not saying that is your issue, but since you didn't mention it in your post I thought I would throw it out there.

 

[mcduhamel]

What water are you using? Are you filtering? Doing any water adjustments?

I'm usually buying spring water and making no adjustments. That, though, is an interesting point.

 

[Lennie]

Water wouldn't really explain the difference between kegging and bottling would it?

 

[audger]

Water wouldn't really explain the difference between kegging and bottling would it?

probably not.

can you describe the flavor any other way than comparing it to something that is flavorless (ever tasted keg lube? there is actually no flavor- only a certain mouth feel)? otherwise it seems pretty obvious theres your problem- kegs have keg lube on them, bottles dont. that would be a reason all your kegged beers 'taste like it' and bottles dont...

 

[CS223]

I'm dealing with the same subtle metallic issue at the moment but with zero brewing experience to call upon, same fanatical cleaning regime with the same chems, RO brewing water. Could it be that the bottles are aging at room temperature and the kegs are kept at serving temperature after fermentation? Think I'm going to bottle a few and let them sit for 2 weeks at room temp, refrigerate two more bottles immediately and then compare them with the refrigerated keg.

 

[Lennie]

I've had a metallic flavor issue before with my Belgian dubbel. I think mine may have been due to oxidation, although one can't rule out water or pH or yeast health as potential causes.

Its possible that kegging can result in more oxidation, depending on how you are handling the beer.

 

[Chuck_Swillery]

This is WAY out there but using a metal spoon to stir and/or aluminum brew kettle? If either is of cheap metal you could get some leaching but you'd likely notice that in both kegged and bottled.

 

[jfrizzell]

Are you purging the head space in your kegs after you hookup the gas? Oxidation perhaps?

 

[Chuck_Swillery]

Are you purging the head space in your kegs after you hookup the gas? Oxidation perhaps?

...nice... hadn't thought about that....

 

[mcduhamel]

Thanks everyone. These are interesting thoughts. I wish I could better describe this flavor. If I knew a BJCP certified judge in the area I'd have it evaluated.

 

[Junkster]

I had a problem that affected all of my draft beer years ago (don't remember the off taste) but it turned out to be the CO2 supply. I changed suppliers (from welding supply to a beverage company) and had no further problem.

 

[petrostar]

I had this issue also and it was It was from force carbonating too quickly. Carbonic acid I what I believe you are tasting.

I use the same supplier for co2 that I did and just set it and forget it for a week. Bumping pressure and rocking only to drink hours later always left that flavor. You could also be getting bad co2 like mentioned before. How do you carb? Try priming a 5 gallon batch in the keg instead of force carbonating. You'll know for sure then. Hope it helps.

 

[Fid]

OP said that they have had the same results with both force carb and priming the kegs. I think purging the head space sounds like the best (or at least easiest) area to trouble shoot from if its something that you haven't done with past brews.
To really trouble shoot it you could maybe try a split batch. Brew a beer that your comfortable with, after fermentation add some priming sugar and keg four gallons and bottle the remainder. Let each condition in the same space and sample side by side when its ready to serve to see if you can discern any differences between the two.

 

[petrostar]

Ah, didn't see that.

 

[mcduhamel]

It does seem like my best option is to split a batch, keg half and bottle half, and record carefully everything I do with the kegged beer. Although I can't rule out oxidation, I do try to purge the head space, although perhaps not sufficiently.

 

[Yambor44]

It does seem like my best option is to split a batch, keg half and bottle half, and record carefully everything I do with the kegged beer. Although I can't rule out oxidation, I do try to purge the head space, although perhaps not sufficiently.

I don't think the head space purging is the issue. I never knew I was supposed to do that for quite a few batches and I never had an issue. It has to be something in the kegging.

You keep mentioning oxidation and I think based on your description you are on the right track. Sometimes we over think these things such as a little splashing on transfer and not clearing the head space and then sometimes we don't pay enough attention and may splash on transfer just enough to cause some beers (lighter in style as you mentioned) to be affected by the process while others not or it is more hidden.

Pay attention to your transfer to the keg and keep any splashing to a minimum. Sometimes my tubing (I use an auto siphon) is too long and goes to the bottom of the keg and curls back up and I catch it splashing in there. Change you beer lines as mentioned earlier and disassemble, soak in PBW or Oxi Clean Free (odorless) rinse well, flush you lines and taps with Starsan after reassembled, then purge that with your beer on tap.

 

[barneygumble]

I had that problem when I sanitized with iodine. I ended up having to change out my beer lines to completely eliminate it.

 

[rhern053]

mcduhamel,

I can't believe you're posting this. I was just obsessing about this same problem yesterday. With me too it's mostly pale ales. Yesterday I did a side by side of my stout and pale ale and only the pale ale had this weird flavor.

I'm pretty sure one culprit to this is the fact that my beers are not drying out sufficiently. I tend to mash too high (like 154) for a dry beer and I usually keep the beer fermenting at a steady 60* (when I should probably let it warm up towards the end to clean up, like a diacetyl rest, but for ales). This has been adding too much of a rounded, slick mouthfeel, along with the funky taste you're explaining.

I'm wondering if it could be the gas, like one poster commented, but the welding supply shop that I fill my tank up with also fills the tanks for the local beverage supply that rents out tanks for keggers and stuff, so I doubt that's the issue.

I think I'm going to try replacing my beer lines. Just read an article on Northern Brewer about dirty beer lines affecting flavor.

Let me know if you figure this out. I'll let you know as well.

 

[rhern053]

Oh! And one more thing. I also noticed that the beer tends to smell a little bit like old StarSan. I try to keep the same batch of StarSan on hand in a bucket for as long as possible, but it does go bad eventually and has this weird odor to it. I'm thinking of being a little less frugal and making fresher batches of StarSan. This could be it too. Just not sure.

 

[Newton]

Interesting thread. In my case, some of my bottle conditioned beers have a slight "plastic" taste, whereas my kegged beers taste premo. Sometimes I wonder if these tastes are all in my head as nobody else seems to notice them...

 

[Yambor44]

Oh! And one more thing. I also noticed that the beer tends to smell a little bit like old StarSan. I try to keep the same batch of StarSan on hand in a bucket for as long as possible, but it does go bad eventually and has this weird odor to it. I'm thinking of being a little less frugal and making fresher batches of StarSan. This could be it too. Just not sure.

I do the same thing and recently started making smaller batches (2.5 vs 5 gallons) so it doesn't get old. Mine seems to work great as a sanitizer, but the water can start to smell "foul" or "dirty" for a lack of a better word after a couple of months of sitting in my 75 degree grain room (I use a bucket with a screw top lid). The PH will still be well under 3. but the water does start to look "dirty".

There is much debate recently about the sanitizing properties of StarSan once the water goes cloudy. Mine clouds up almost immediately after making it, which to me means it doesn't work at all, ever if the cloudy theory holds true.

 

[rhern053]

I found a thread on carbonic acid. Apparently it is created when Co2 is introduced and dissolved into a liquid. It's supposed to go away after about a week. I wonder if this could be what we're tasting/smelling. If what I notice in the beer is gone after a week or so, then I'll assume that it was this.

FWIW, I don't know what carbonic acid tastes like, so I could be way off. Does anyone know what sort of notes it puts out?

 

[Yambor44]

I found a thread on carbonic acid. Apparently it is created when Co2 is introduced and dissolved into a liquid. It's supposed to go away after about a week. I wonder if this could be what we're tasting/smelling. If what I notice in the beer is gone after a week or so, then I'll assume that it was this.

FWIW, I don't know what carbonic acid tastes like, so I could be way off. Does anyone know what sort of notes it puts out?

FWIW I just stumbled upon this post in a Beer Line Cleaning thread. Don't know if it applies to you or anyone else but thought it might be good to know

When using PBW or any other Caustic (basic) solution, it is best not to use CO2 to pressurize your vessel to push you cleaning solution through. CO2 will dissolve in to solution to form carbonic acid and neutralize your cleaning solution.

 

[mcduhamel]

rhern053 (and others):

I wonder if it is, after all, carbonic acid? The thing is, I don't know what that tastes like, but it does seem that this flavor tends to dissipate (a bit) over time. Yet, most people who force carbonate don't seem to report this flavor, and I don't think I'm doing anything differently. It's not like I'm pressurizing at 20 psi or anything. Usually I set to around 12 to 13 and leave it there for 4 or 5 days.

 

[rhern053]

I'm going to take a look at the beer after a little while and see if it might be the acid. I'm also going to take a look at my tap water. I noticed a similar aroma in some water from the sink. Anyways, good look with your ventures. Thanks for the tips everyone. Cheers!

 

[beertastic]

......

Pay attention to your transfer to the keg and keep any splashing to a minimum. Sometimes my tubing (I use an auto siphon) is too long and goes to the bottom of the keg and curls back up and I catch it splashing in there. Change you beer lines as mentioned earlier and disassemble, soak in PBW or Oxi Clean Free (odorless) rinse well, flush you lines and taps with Starsan after reassembled, then purge that with your beer on tap.

Off topic, but...

I attach a racking cane to the end of my siphon tubing to alleviate this problem. The end of the racking cane then sits gently on the bottom of the keg. Actually I cut off the bend of a racking cane to make it straight which works better. Costs $3, no splash, and helps you sleep at night

 

[beertastic]

I'm still figuring out kegging, but here's what I would do:

1) Keg condition. Buy a brand new picnic tap for $8 and attach. Flip the keg upside down and gravity/cask serve. Still taste it? It's not your lines or your CO2. Taste it? It's your keg or your process.

2) If it passed that test, I would keg condition another batch (or the same one if there is enough existing pressure). But never hook it up to CO2. Just serve it through the lines. Hopefully now you can weed out either the lines or your CO2 source.

 

[mcduhamel]

I can now report that I have eliminated this flavor, and that therefore I suspect it was either excess carbonic acid or simply "greenness." Here's what I did: I detached the gas supply and purged the head space, and then let it sit for 4 days in the fridge. Then I reattached the gas and pressurized to 7 PSI and served. The off-flavor is entirely gone. In its place I have a well-carbonated, very tasty ESB!

I will be modifying my process going forward. I'll carbonate for 4 or 5 days, then purge and let the beer sit without additional pressure for a week. Then I will purge again, let the beer settle, and pressurize to dispensing pressure. I'll bet this solves my problem.