Why on earth does my beer taste like metal??

Hi Folks,

I brewed a partial mash mint chocolate stout for Christmas this year. It spent 3 weeks in the primary and 4 weeks bottle conditioning at 68-71 degrees.

I popped one open last week and it was most definitely still green. I tried one again yesterday and the greenness had dissipated, only to be replaced by a horrible rusty metal flavor. It was absolutely disgusting.

Where this flavor came from is a mystery to me. My tap water tastes fine and I use starsan at the proper concentrations. This batch was boiled in an aluminum kettle, but I have made at least 10 other batches in said kettle and never had a hint of metal before. I thought for a second it could have been the caps, but there was no hint of rust or corrosion on the caps of the ones I tried.

When reading past posts about metallic off flavors, it was never mentioned when they became apparent. What is especially confusing to me is that this beer tasted pretty darn good going into the bottles. It wasn't my best ever, but I was satisfied that it was going to be a better than average Christmas beer.

What could have happened between bottling and now that would have contributed such terrible flavor? It is incredibly strong, completely overpowering any other flavor of the beer.

Is there an infection that causes metallic taste? I saw it mentioned that oxidation combined with roasty grains can give a metallic flavor; does anyone have experience with this? When this happens is it an overwhelming flavor?

I try to minimize introducing oxygen to the beer during the bottling process, but I am far from perfect.

In any case, I hope some of the more experienced brewers will be able to give me an idea of how my pretty decent beer went into glass bottles and transformed into something I wouldn't give my worst enemy.

Thanks!

http://www.kroc.org/Links/TroubleshootingGuide.htm
http://www.howtobrew.com/section4/chapter21-2.html

I have read those and several other sources about where metallic beer generally comes from.

However, as I explained in my original post, I don't believe that the normal causes for metallic off-flavors are the cause for mine. I used fresh ingredients, my kettle has been used for 10 batches without any hint of metal, and most importantly (in my view), if the metallic flavor was caused by one of the reasons listed in those references, it would have shown up when I tasted the beer before bottling.

I could be wrong about that, but please don't assume that posting here was my first action after discovering this taste in my beer. I have read all of the standard references on line as well as several discussions on this and other homebrewing forums.

And I'm still confused.

Do you have a aluminum boil kettle or brass fittings anywhere in your system?

Both of these leech metal if they are not properly treated to create a passive oxygen layer. Even after the passive oxygen layer has been established, cleaning them with any sort of caustic cleaner, heavy acid based cleaner (or soaking in an acid-based sanatizer, like starsan), oxyclean-type oxygen based cleaner, or flat out scrubbing them with anything coarse will also remove the passive oxygen layer.

If everything in your system isn't stainless steel, you could have accidentally leeched metal into your wort.

No brass fittings. I do have an aluminum boil kettle, but I would be a little surprised if that is the culprit since:

1. I have brewed several other batches in this kettle with no resulting metallic flavor
2. Palmer says that aluminum won't contribute to a metallic flavor unless your water has a PH of around 9, and mine does not, and
3. If it was the kettle, wouldn't the flavor have shown up before I bottled?

I think the last point is my big question. I'm having trouble with the general reasons for metallic flavors because it seems to me that all of the standard causes should have shown up after fermentation and before bottling. But my beer tasted good going into the bottles.

I'm stuck on the idea that something happened during conditioning, but I can't figure out what.

Did you try more than one bottle containing this "flavor"?

To the point of the others, the more you use your aluminum kettle, the more you clean it, the higher the chance of the aluminum breaking down and contributing off flavors.

So far, I've tried two bottles and both had the metallic taste. But I have a couple more in the fridge that I wil try in a day or so.

meis1212 said:

To the point of the others, the more you use your aluminum kettle, the more you clean it, the higher the chance of the aluminum breaking down and contributing off flavors.

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This makes sense to me, but do you think if the flavor was coming from the kettle I would be able to taste it before bottling?

I ask this partially because I just bottled another batch yesterday that was brewed in the same kettle. It was the best beer I've ever made going in to the bottles. Should I be worried that this new batch is also going to develop a metallic taste?

I doubt it was the kettle, unless you were scrubbing it while the wort was in the pot.

Aluminum oxidizes the instant it touches oxygen to form the protective layer.

Unless you scrubbed the hell out of it and didnt rinse it out at all before putting your wort in i doubt its the kettle. To get enough metal into the beer to actually taste it, you would have needed a good amount to have made it into the fermenter.

TopherM said:

Do you have a aluminum boil kettle or brass fittings anywhere in your system?

Both of these leech metal if they are not properly treated to create a passive oxygen layer. Even after the passive oxygen layer has been established, cleaning them with any sort of caustic cleaner, heavy acid based cleaner (or soaking in an acid-based sanatizer, like starsan), oxyclean-type oxygen based cleaner, or flat out scrubbing them with anything coarse will also remove the passive oxygen layer.

If everything in your system isn't stainless steel, you could have accidentally leeched metal into your wort.

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I didn't know brass was bad for brewing. I have three brass fittings on my SS pot, it holds the SS Blichmann temperature gauge (see pic). Sounds like I need to get rid of it. How bad do you think that is?

How did you get the mint flavor? Real mint or a flavor extract? I find extracts can leave funny tastes in the beer, especially as an aftertaste.

Is your beer good? Then its fine.

The issue some people bring up with brass is that lead is used during the manufacturing of brass, so you need to make sure you wash that lead off with an acidic solution of some sort.

I dont think beer would be nearly acidic enough to worry about it, but if it makes you sleep better plug that hole until you can get a stainless tube for your thermometer.

It was real mint.

Half an ounce of spearmint, bruised in a bag against the countertop, added at flameout and removed before transferring to the fermenter.

FuzzeWuzze said:

Is your beer good? Then its fine.

The issue some people bring up with brass is that lead is used during the manufacturing of brass, so you need to make sure you wash that lead off with an acidic solution of some sort.

I dont think beer would be nearly acidic enough to worry about it, but if it makes you sleep better plug that hole until you can get a stainless tube for your thermometer.

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More good stuff. One of the first things I did prior to starting brewing was to boil my pot and IC in a water/vinegar mix. I think I used 2 gallons of vinegar and enough water to cover the IC, which would have more than covered the temp probe area.

I think I'll still replace the brass though.

Thanks!

I didn't know brass was bad for brewing. I have three brass fittings on my SS pot, it holds the SS Blichmann temperature gauge (see pic). Sounds like I need to get rid of it. How bad do you think that is?

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Brass is in the same boat as aluminum. Most of the brass you buy contains about 2% lead, though they are starting to outlaw that mix slowly across the country. As long as it has the passive oxygen layer, it's 100% fine. The passive oxygen layer is created the first time boiling H2O touches the brass/aluminum for a few minutes. As long as you don't scrub it with caustic or highly acidic cleaners/sanitizers, your brass fittings stay oxidized pretty much indefinitely.

If you want to be sure you're safe, just take all of your brass fittings and boil them in water for about 5 minutes, and they'll be good to go.

I'm going to bump this up again to see if any ony else has any ideas or suggestions.

Quick recap: my mint chocolate stout has a overwhelmingly strong metal aftertaste. This taste was not apparent when I was bottling, so I have more or less ruled out hard water and/or metal extraction from my brewing process. The only suggestion that seems reasonable to me is that somehow the beer got incredibly oxidized during the bottling process, but I didn't change my process and I have never had this problem before.

I DID use creme de cacao liqueur as a priming agent. Could that somehow have messed things up? It carbonated very well, actually. But maybe it added some other unwanted flavor?

I really appreciate any ideas or suggestions that people might have.

I recently brewed a stout that had a pronounced metallic flavor going into the bottle. This has disappeared entirely over the last 3 months of aging. I realize Christmas is right around the corner, but you may find that your beer will age out fine over time.

RobertRGeorge said:

I recently brewed a stout that had a pronounced metallic flavor going into the bottle. This has disappeared entirely over the last 3 months of aging. I realize Christmas is right around the corner, but you may find that your beer will age out fine over time.

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Thanks for the input!

This is the first time I've heard some one say the metal went away. I really don't mind not having it for Christmas as long as I don't have to dump it. If it turns out ok after 3 or 4 months, I'd be thrilled.

tko17 said:

Thanks for the input!

This is the first time I've heard some one say the metal went away. I really don't mind not having it for Christmas as long as I don't have to dump it. If it turns out ok after 3 or 4 months, I'd be thrilled.

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Almost all beer with off tastes will mellow out after 3-4 months FYI.

I do just about anything I can to avoid dumping a beer. Mix it with other beer, age the heck out of it, choke it down over a long time in between better batches, etc. I did dump a couple of batches a few years ago because I was reusing yeast and had some contamination by what tasted like wild yeast, but unless the taste is REALLY ugly I've managed to drink it all. Good luck!

What yeast did you use?

I've had metallic sort of "flavors" from S-04 yeast sometimes, they do fade with age but it's usually more than I'd want to wait for so just man up and drink through it But it's possible to have an off flavor like this appear as other flavors mellow during fermentation/initial aging.

I super highly doubt it's the aluminum kettle, I use one and no issues, even with some scrubbing.

One last thing, I found a metal taste to a batch once when I used a chrome plated (or whatever it was, it was shiny) electric element for the first time, the chrome vanished, hey I wonder where it went...oh I drank it. Eww....

Just throwing out another possibility that hasn't yet been mentioned.

Read a thread on here where the brewer was getting metallic tasting beers and it turned out that it was metal dust, from the caps getting crimped closed, around the lip at the top of the neck of the bottles. Seemed like it was introduced by contact with the head or just getting sprinkled when pouring.

Someone else who mostly drank straight from the bottle also reported similar

Any chance this could be the cause?

Ogri said:

Just throwing out another possibility that hasn't yet been mentioned.

Read a thread on here where the brewer was getting metallic tasting beers and it turned out that it was metal dust, from the caps getting crimped closed, around the lip at the top of the neck of the bottles. Seemed like it was introduced by contact with the head or just getting sprinkled when pouring.

Someone else who mostly drank straight from the bottle also reported similar

Any chance this could be the cause?

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I could see this happening if you are one of those people who flip their bottles upside down to carbonate.

Its likely just the mint or one of the other things he added that is just giving that acidic metal taste, it will mellow out with time.

Did you use cocoa in the boil for the chocolate?

FuzzeWuzze said:

Almost all beer with off tastes will mellow out after 3-4 months FYI.

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Just....no.

Ogri said:

Just throwing out another possibility that hasn't yet been mentioned.

Read a thread on here where the brewer was getting metallic tasting beers and it turned out that it was metal dust, from the caps getting crimped closed, around the lip at the top of the neck of the bottles. Seemed like it was introduced by contact with the head or just getting sprinkled when pouring.

Someone else who mostly drank straight from the bottle also reported similar

Any chance this could be the cause?

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I've had plenty of commercial beers that have a metallic flavor on the lip from the cap. But the flavor has never transferred into the beer, and if the beer is being poured into a glass, I don't think this would be a cause for the flavor in the beer.

OP, brew with store-bought water (any) and let us know how it turns out. As with any problem, the key is to divide it in half, then again, then continue till the problem is laid bare.

Not to hijack you thread (or to do exactly that since I have the same problem) but I got very few responses to my post and would love to hear some opinions from the same folks that discussed here. This is what I posted:

So in 2 separate batches I got a BAD alkaline metallic taste. My first thought was sanitation problems, but I haven't changed sanitary processes between batches so probably not. I'm making starters now to harvest yeast and pitch healthy. Here comes my question... before I started using my new stainless 4qt. to make starter wort I was using a Teflon coated (non-stick of some sort) one before it. It had some scratches, but assumed star san, boiling water, then adding and boiling DME would be ok. So did I get 1) Teflon in the starter 2) leeched metal from exposed scratches 3) infection or 4) all of or a mix of 1, 2, and 3. Thanks for any insight.

Thanks again and berate me if you must for the hijack. Just trying to learn something!

Are you pitching the entire starter or decanting off all the liquid?

Regardless, short of scratching your entire teflon pan to hell i dont see how a large enough amount of liquid in even a full pitched starter could effect 5 gallons of beer.

PseudoChef said:

Did you use cocoa in the boil for the chocolate?

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I did. Could that be the issue??

passedpawn said:

OP, brew with store-bought water (any) and let us know how it turns out. As with any problem, the key is to divide it in half, then again, then continue till the problem is laid bare.

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This is what I've tentatively identified as the probable cause. Turns out I have chloramines in my water and I hadn't been treating for it. Most describe chlorophenols as a band-aid medicinal taste, but I found on wikipedia that they can also cause a harsh metallic taste.

After this discovery, I went back and tasted a bunch of my other beers and I was able to indentify (or at least convince myself that I identified) other cholophenol flavors. These were flavors that had been bothering me, but that i had ascribed to other problems. Now I think it was all the chloramines.

I'm brewing a new batch as we speak (almost at strike temperature...) and I've treated my water with campden. Hopefully this batch turns out to be my best yet!

Thanks for all your help and suggestions, folks. It's really appreciated.
.

tko17 said:

I did. Could that be the issue??

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Yep. Can't explain it, but talked to more than one person who has gotten a metallic off flavor from using cocoa powder. I could maybe have a reasoning for it if it were Dutch process, but I'm assuming it wasn't that either.

PseudoChef said:

Yep. Can't explain it, but talked to more than one person who has gotten a metallic off flavor from using cocoa powder. I could maybe have a reasoning for it if it were Dutch process, but I'm assuming it wasn't that either.

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Nope. It wasn't Dutch process.

I'll stay away from the cocoa in the boil from now on. I found it to be a very ineffective way to get flavor in any case. From here on out my chocolate comes from nibs in the secondary.

Although bottling with creme de cacao was an interesting experience. I wish my beer didn't taste like a rusty nail so I could judge the flavor effect of priming with liqueur.

I cracked my first brew open last night. I loved it. Wifey spit it out and said it tastes like metal. Waiting on my beer swilling neighbor for his opinion. In the meantime, I am obsessing. After reading, I am now thinking it may be the water. How do you test for these chloramines?

mike024 said:

How do you test for these chloramines?

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If they're in your water they'll be listed on the water report from your public water utility.

I've been talking to home and craft brewers in the neighborhood, and I think that metallic tasting chlorophenols are more prevalent in darker beers and band-aid chlorophenols are in other styles...

That opinion is completely unscientific though.

I thought I'd chime in on this as this just happened to me... I brewed a Double Chocolate Milk Stout last month and just tried it and it had a metallic aftertaste. Great flavor up front, just a mild metal taste at the end. I"m 10 batches in and this has never been a problem before.

I have all SS pots and fittings so it can't be from metal leaching. Also, I have pretty great water here but I still filter to get out the Chlorine. I used Hershey's Cocoa 100% Cacao Special Dark powder in the last 15 min of the boil and then cocoa nibs in the secondary.

The only other issue that I've had with this batch is that after I burst carbonated for a few days I dialed it down to serving pressure for a week or so and then my regulator got a leak in the shut-off valve. When I went to pour a glass after a week it was dead... no gas at all. The beer had gone flat and I don't know how long it had been that way. I switched CO2 tanks and fixed the problem and again burst carbonated it and left it at pressure for about 5 days. Tonight I when tried it the carbonation was ok, but it has this aftertaste.

Can I be getting it from the carbonation problem or should I be more concerned about the Cocoa Powder?

I"m going to give this some more time to mellow and hopefully it will drop off the metal aftertaste.

Brewme2 said:

The beer had gone flat and I don't know how long it had been that way. I switched CO2 tanks and fixed the problem and again burst carbonated it and left it at pressure for about 5 days. Tonight I when tried it the carbonation was ok, but it has this aftertaste.

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After the beer went flat, it's likely that the escaped CO2 left sodium-like properties behind. If you have ever tasted water after it was carbonated, and then went flat again, you'll know that it definitely does not go back to tasting like plain water again. It tastes almost saline/metallic. Re-carbonate that, an it'll be better, but it won't be like it was when it was freshly carbonated. It will taste strong of minerals, which could be the aftertaste you're experiencing.

Brewme2 said:

I used Hershey's Cocoa 100% Cacao Special Dark powder in the last 15 min of the boil and then cocoa nibs in the secondary.

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Something about that worries me. In practice, you never actually boil cocoa when you make hot cocoa. You boil water, then add cocoa to it after it's removed from the heat. Boiling something for 15 minutes can really change it, possibly making it bitter. I really don't have any idea what might happen to cocoa.
James from Basic Brewing Radio added Count Chocula cereal to a mash for a chocolate stout, and he liked it a lot, so I would think cocoa would be okay to boil, but I just don't know. I have personally tasted the side effect of leaving ingredients in the boil for too long, such as cinnamon, and I have learned to add that sort of flavoring post-boil. You may even want to consider making hot-cocoa, then letting it chill, and adding it to the carboy. I'm just thinking out loud. Take it with a grain of salt.

Brewme2 said:

I"m going to give this some more time to mellow and hopefully it will drop off the metal aftertaste.

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Hopefully so.

I'm going to add something here.

I've found brown sugar (molasses) to give a slight "metallic" taste in beer when it gets fermented, at least to my palate, while other people seem to agree. If you were to add it to a keg or bottling bucket after fermentation it may fare better, never tried it. The metallic taste seems to age out slowly. One of my Christmas ales turned really good after a year in the bottles, with very little or none of that metallic taste left.