[bayareabrewer]

Does metallic only come from rust or can it be from yeast? I have a keg that has a bit of a penny taste. Not the faucet as I swapped kegs. Yeast was 4th gen Rustic/3726.

Frequently a sign of oxidation

While I won't rule that out, my cold side practices are pretty solid.

One thing I've noticed is it is more pronounced when freshly poured and reasonably carbonated. If I neglect it for an hour it's much less noticeable. The CO2 is for sure enhancing it. Maybe the acidity of the gas in solution. Can't be the gas itself as it is shared with 3 other kegs.

I'm with you on high carbonation enhancing/causing a metallic flavor in beer.

[Stevie]

The beer is only at 2.5 vol, same as all of my other kegs, so I don't think the carbonation is the cause.

I'm brewing this weekend with Rustic so that will tell me if it's the yeast.

[coolman26]

I just bought Rustic this weekend. Will be interested in this.


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[Stevie]

I just bought Rustic this weekend. Will be interested in this.


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I didn't get it until this batch. I'm leaning towards the keg.

[majorvices]

If its a split batch with different yeasts and the other keg is fine, sounds like the yeast.  Although I agree with Denny, I usually associated metallic off-tastes with oxidation. 

Four generations of farmhouse yeast may have picked up something along the way, in terms of mutations, infections, etc. I've done up to 6 generations of lager yeast, and have noticed that the later generations were not as squeaky clean as the first couple. Now I tend to stop at three.

What if one keg needs passivated and one does not? Metallic flavors, except for in some cases of dark beers at very cold temps, almost always indicate metal got into your beer somehow. Either through the water or though an item that is in need of passivation.

Also, every passivation process I have ever done say drain the acid, but don't rinse for 24 hours.

[Stevie]

Both kegs are new AIH kegs. I received two 5 and two 2.5 gallons. I broke them all down to clean and sanitized with iodophor. Since the parts were all mixed up (posts, lids, poppet) it is impossible to say which keg is the offender. From here I am going to break them all down again, clean, visually inspect, passivate, dry, sanitize, and purge before they get used again. Hopefully there isn't any surface rust that requires elbow grease to remove.

ETA - it's not the iodophor. I use 12.5ppm solution, there is generally two day gaps between sanitizing and filling, and I have never had an issue before.

[chumley]

If its a split batch with different yeasts and the other keg is fine, sounds like the yeast.  Although I agree with Denny, I usually associated metallic off-tastes with oxidation. 

Four generations of farmhouse yeast may have picked up something along the way, in terms of mutations, infections, etc. I've done up to 6 generations of lager yeast, and have noticed that the later generations were not as squeaky clean as the first couple. Now I tend to stop at three.

What if one keg needs passivated and one does not? Metallic flavors, except for in some cases of dark beers at very cold temps, almost always indicate metal got into your beer somehow. Either through the water or though an item that is in need of passivation.

Also, every passivation process I have ever done say drain the acid, but don't rinse for 24 hours.

I just have a hard time believing that a manufacturer would sell a brand new keg without telling you that it needs passivation.  I would assume that all new kegs come passivated.  I have only bought one new keg, and that did not need passivation.

The only time I have ever had to passivate brewing equipment was a 55 gallon stainless steel drum that was cut in half to form two kettles.  I have never had to passivate a keg, and I own at least a dozen of them.

[HoosierBrew]

I have never had to passivate a keg, and I own at least a dozen of them.

Same here, and as my wife would tell you, I own a few more than that. Some close to 25 yrs old, some newer.

[majorvices]

If its a split batch with different yeasts and the other keg is fine, sounds like the yeast.  Although I agree with Denny, I usually associated metallic off-tastes with oxidation. 

Four generations of farmhouse yeast may have picked up something along the way, in terms of mutations, infections, etc. I've done up to 6 generations of lager yeast, and have noticed that the later generations were not as squeaky clean as the first couple. Now I tend to stop at three.

What if one keg needs passivated and one does not? Metallic flavors, except for in some cases of dark beers at very cold temps, almost always indicate metal got into your beer somehow. Either through the water or though an item that is in need of passivation.

Also, every passivation process I have ever done say drain the acid, but don't rinse for 24 hours.

I just have a hard time believing that a manufacturer would sell a brand new keg without telling you that it needs passivation.  I would assume that all new kegs come passivated.  I have only bought one new keg, and that did not need passivation.

The only time I have ever had to passivate brewing equipment was a 55 gallon stainless steel drum that was cut in half to form two kettles.  I have never had to passivate a keg, and I own at least a dozen of them.

New stainless is very often in need of passivation especially if it is Chinese. In the case of new stainless it isn't usually rust, it is the left over specs of metal left over from the manufacturing process. Yeah, it may not be needed on most corny kegs but if you suddenly pick up metallic flavors that is the first palace I would look. FYI I never passivated any of my stuff when I was homebrewing either. That doesn't mean some of it shouldn't have been though.

I agree it may be something else, but a new keg and the beer has metalic flavors? That's the first place I'd look.

[Stevie]

I figure it could be as small as the spring from the poppet that is causing it. I could easily see something like that getting delivered without passivation.

[HoosierBrew]

I agree it may be something else, but a new keg and the beer has metalic flavors? That's the first place I'd look.

Probably half of my kegs were used when I got them and there was no issue, and the new ones I bought luckily didn't have that issue. But it's good to have the info anyway.

[Stevie]

Keg just blew. I'll rip it apart tomorrow along with the faucet as a just in case. Shot an email over to AIH to see if they had other similar reports. I'll update at some point.

[majorvices]

I agree it may be something else, but a new keg and the beer has metalic flavors? That's the first place I'd look.

Probably half of my kegs were used when I got them and there was no issue, and the new ones I bought luckily didn't have that issue. But it's good to have the info anyway.

Aside from dark malts and cold temperatures I'm just not sure of any other off flavors that cause "metallic". Maybe strong, unrinsed iodophor? I am not familiar with any yeast off flavors that produce "metallic" as an off flavor. I'd be open to any other ideas of what it could be. I admit that I don't think I ever experienced it as a homebrewer and I had over 20 used kegs and never experienced an issue that I was able to pick up on.

I have had it happen on a boil kettle after about 2 years of use and I have experienced it at other breweries who have put on new equipment and didn't know (or didn't bother) to passivate. Unless you have visual rust it could be the problem takes care of itself over time.

As an aside, we use a "crowler" machine and if I don't thoroughly rinse those crowelrs before I fill one I will pick up metallic off flavors, most likely from residue left over from manufacturing.

[Stevie]

The keg looks ok after a visual once over. Going to run it through my normal cleaning process and try passivating it with Star San, lots of Star San.

Faucet seems good as well.

Won't be able to follow up for at least week on this keg and two weeks on my current crop of Rustic.

ETA - AIH has replied and hasn't had any other reports of issues. Told me to keep them informed.

[weazletoe]

Guess I got nothing to add. I thought the thread said Metallica.