Troubleshooting Metallic Taste in Two Beers

[geoffm33]

I am trying to track down a metallic taste I have in two of my beers. Both beers tasted great out of the fermenter. But developed a metallic taste shortly after carbonating. The chance I could have overcarbed is pretty high, but the 30PSI for 24hours seems to be a widely used method.

Here are the similarities between the two occurrences:

1) Both were burst carbed using the 30PSI for 24hours then back it off to serving pressure (12PSI at 43°).

2) Both happened in the same keg. The keg and components were thoroughly cleaned with Oxyclean, scrubbed, hot water rinsed and sanitized with StarSan prior to racking. There was no noticeable smell in the keg prior.

3) One was a Brown Ale, one was an Oatmeal Stout. Both used Nottingham and shared some similar specialty grains (Chocolate Malt, Victory, Crystal).

4) It's possible that when I backed off from 30 to 12PSI that I didn't purge the keg both times.

The Oatmeal Stout was the first occurrence and was for a party so most of it was gone before I had a chance to correct it. The Brown Ale is still kegged but it is off the gas and I've been purging the co2 daily for the past week. It's tasting better, but still has a metallic taste.

I had a feeling that my pressure gauge was off when one of my taps was pouring significantly faster than the other. Both were at the same pressure, same length and ID beer lines. So if it were off by a few PSI then I could have had it at 32, 33, 34+ PSI for 24 hours.

Is it possible that the beer style is more prone to overcarbing?

I've had two other kegged beers in a different keg in the same setup and those have tasted great. One a Blond Ale and the other a Pale Ale. These have both been carbed with set and forget.

Thanks!

 

[day_trippr]

I'd say there's a clear relationship between carb method and beer quality hiding in plain sight...

Cheers!

 

[hunter_le five]

I've had metallic flavors in newly-carbed kegs a couple times before. Both times the flavor eventually dissipated. I'm guessing it had something to do with the buildup of carbonic acid.

In your case I'm guessing it has to do with rapidly carbing/possibly slightly over carbing. I'm willing to bet that if you leave it dialed down at the proper pressure and set/forget for a couple weeks, the flavor will go away.

 

[Yooper]

Before I saw the types of beer you made the first thing that jumped out at me was that there were dark malts involved.

One of the first things I learned when I became a beer judge was that early oxidation and dark malts tend to result in a metallic flavor on the sides of the tongue. My bet is that it is oxidation.


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[geoffm33]

I'd say there's a clear relationship between carb method and beer quality hiding in plain sight...

Cheers!

Darn you and your logic!

I've had metallic flavors in newly-carbed kegs a couple times before. Both times the flavor eventually dissipated. I'm guessing it had something to do with the buildup of carbonic acid.

In your case I'm guessing it has to do with rapidly carbing/possibly slightly over carbing. I'm willing to bet that if you leave it dialed down at the proper pressure and set/forget for a couple weeks, the flavor will go away.

I've had it off gas completely for a week, you had good results just letting it sit on gas at the proper pressure?

 

[geoffm33]

Before I saw the types of beer you made the first thing that jumped out at me was that there were dark malts involved.

One of the first things I learned when I became a beer judge was that early oxidation and dark malts tend to result in a metallic flavor on the sides of the tongue. My bet is that it is oxidation.


Sent from my iPhone using Home Brew

That's a good point. But would oxidation show signs that early? In the fermenter for 2 weeks, rack to keg, chill overnight and hit it with 30PSI for 24 hours, pull back the regulator to 12 PSI. Taste after a few days.

So from boil kettle to glass in about 17 days and get that taste.

 

[hunter_le five]

I've had it off gas completely for a week, you had good results just letting it sit on gas at the proper pressure?

That was my experience. I released the pressure from the keg, and set it to ~12psi (depends of course on temp/style), and then left it alone for 2-3 weeks, other than the occasionally draw off a bit to taste test. The off flavors eventually did disappear in both instances.

After reading Yooper's post though, I could be completely misdiagnosing the problem.

 

[geoffm33]

That's a good point. But would oxidation show signs that early? In the fermenter for 2 weeks, rack to keg, chill overnight and hit it with 30PSI for 24 hours, pull back the regulator to 12 PSI. Taste after a few days.

So from boil kettle to glass in about 17 days and get that taste.

Nevermind Yooper, found this post of yours while researching the issue:

I don't know the cause of the flavor issue, besides what everyone else has already said, but I wanted to mention some additional "flavors" you can get from oxidation. In early stages, oxidation can present as more of a "feel" on the sides of the tongue. It is not quite metallic, and just a bit astringent, on both sides of the tongue. As the beer ages, it can start to taste like sherry (that's called "madierized") and change color a bit. When oxidized beer gets older and through those two stages, then it can taste stale and like wet cardboard. So, oxidized beer doesn't always taste like wet cardboard unless it's terribly severe. Sometimes it's just sherry-like.

So quite possible it's oxidation. And possibly overcarbed. I'll let it sit for a while and see how it develops.

 

[day_trippr]

Two additional comments: one, you never mentioned anything that would suggest you may have induced oxidation; and two, the simplest most evident explanation is usually the correct one...

Cheers!

 

[geoffm33]

Two additional comments: one, you never mentioned anything that would suggest you may have induced oxidation; and two, the simplest most evident explanation is usually the correct one...

Cheers!

True. I siphoned from the fermenter to the keg with the siphon tube all the way to the bottom. And purged O2 right after sealing. But you never know.

I'm hoping it's overcarbed.

 

[Yooper]

True. I siphoned from the fermenter to the keg with the siphon tube all the way to the bottom. And purged O2 right after sealing. But you never know.

I'm hoping it's overcarbed.

I hope so too! I hope that I'm wrong, and that it's not oxidation showing. I do hope it's simply overcarbed and you're getting carbonic acid bite.

It's true what I posted earlier- about a "sherry" flavor- but in dark beers, often there is a slight "metallic" component to early oxidation. Sometimes that "sherry" flavor is expected and nice in certain beers- like barleywine. Oxidation is responsible for that.

 

[sloanb27]

I am trying to track down a metallic taste I have in two of my beers. Both beers tasted great out of the fermenter. But developed a metallic taste shortly after carbonating. The chance I could have overcarbed is pretty high, but the 30PSI for 24hours seems to be a widely used method.

Here are the similarities between the two occurrences:

1) Both were burst carbed using the 30PSI for 24hours then back it off to serving pressure (12PSI at 43°).

2) Both happened in the same keg. The keg and components were thoroughly cleaned with Oxyclean, scrubbed, hot water rinsed and sanitized with StarSan prior to racking. There was no noticeable smell in the keg prior.

3) One was a Brown Ale, one was an Oatmeal Stout. Both used Nottingham and shared some similar specialty grains (Chocolate Malt, Victory, Crystal).

4) It's possible that when I backed off from 30 to 12PSI that I didn't purge the keg both times.

Thanks!

Ignore what everyone is saying here. The reason why you have a metallic taste is because you are adding metal ions (iron) when you scrub stainless steel. Not all stainless is the same, which means it does not all clean the same.

In food manufacturing, EDTA is used to remove it, otherwise rinse your keg with citric acid/water solution before you sanitize. If you wash your keg the day before (as long as it is completely dry) the iron will oxidize and you should be good to go as well.

Personally, I have some food grade EDTA that I use to remove the metallic flavor whenever it happens to me...so far 2 batches out of about 75. Iron ions dissolves in acidic solutions (wort, fermented beer) and the taste threshold is extremely low...something like 2-5 parts per million. It literally only takes about a pinch of the EDTA to remove the metal flavor instantly. Use about 1/8 to 1/4 teaspoon per 5 gallons.

By the way, don't let the big scientific name for EDTA to scare you...it chemically reacts with both calcium and iron to produce harmless salts.

You can research it more, or just buy the stuff for cheap on amazon. there are two different kinds, the one you need is here:

http://www.amazon.com/MakingCosmetics-Inc-EDTA-4-4oz-125g/dp/B005VEDTEO

 

[geoffm33]

UPDATE: After taking it off gas and purging for about a week I put it back in gas at serving pressure for another 5 days.

Metallic taste is greatly diminished to non-existent.

 

[day_trippr]

Imagine that.

It was a horsie after all, and not a zebra - or a unicorn

Cheers!

(friends don't let friends burst-carb)

 

[geoffm33]

Imagine that.

It was a horsie after all, and not a zebra - or a unicorn

Cheers!

(friends don't let friends burst-carb)

Lol. Truth.

 

[GnenieGone]

So after boiling my first stout. I tested after drawing for gravity check. Sure enough a tinny/coin like taste appeared. First time ever.

This is my 6th brew but first stout. Did one last night. I dont buy metallic ions being scubbed off. Once you rinse, any small metal you might have scrubbed would be gone. Aluminum does not spontaneously shed material and with a melting point of like 2000, think were good.

Because stouts and porters appear to be a common theme, at least from my research, pretty sure it has something to do with grains. Just logical deduction until more data is gathered and verified. Anyone have data for this issue?

Additional notes:
The specific gravity for Aluminum is about 2.6 and Aluminum oxide is around 1.6. These would all fall out to the bottom of the wort/keg, overtime, unless stirred back up into the liquid. I'd be curious if anyone had a metals check performed on their brew once this issue was discovered. Any taste/aroma is a physical chemical reaction, thus something real is present, and should be able to be measured.

 

[GnenieGone]

Discovered a thread by FlyGuy back in 2007 about aluminum pots. Thought I'd share. It at least makes the most sense to me about the physical nature of aluminum pots. I did not oxidize my pot prior to the first brew in March and yet no metallic taste. It came out great. Are we sure it's not the grains/bad/combo..whatever???
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The 'aluminum vs. stainless steel' (SS) pot debate pops up frequently, and given that we tend to see lots of new homebrewers enter the hobby shortly after Christmas, perhaps it is timely to post an FAQ on the subject.

Q: Is an aluminum pot OK for a boiling kettle in homebrewing? My LHBS only recommens using stainless steel.

A: Both aluminum and SS pots are excellent in homebrewing, and each has its own advantages and disadvantages, so it is purely a personal preference. Here are some considerations:

Aluminum Pots:
Pros:
- considerably less expensive than SS
- much better at conducting heat than SS, which means faster boils, faster cooling, and less chance of scorching
- not as heavy to lift as SS

Cons:
- oxidizes easily, meaning that oxygen-based cleaners (e.g., Oxyclean, One-step) cannot be used (Note: caustic or other similar clean-in-place solutions can definitely not be used, which is why the brewing industry generally does not use aluminum.)
- passive oxide layer must be built up before brewing (**see note below) with a new aluminum kettle, although it is very easy to maintain

Stainless Steel Pots:
Pros:
- can be cleaned by oxygenated/CIP cleaners without damaging the pot
- passive oxide layer that protects the pot is not as easy to remove as aluminum
- they are really shiny and look cool!

Cons:
- expensive
- not nearly as good at conducting heat as aluminum

Myths About Aluminum Pots:
- Aluminum pots will cause Alzheimer's disease. FALSE. This myth was debunked years ago by the medical research community, and the US National Institutes of Health and Health Canada have long since ruled out a connection between Alzheimer’s disease and aluminum cookware. If you don’t believe me, see the following:
http://www.alzheimers.org.uk/site/scripts/documents_info.php?documentID=99
http://alz.org/alzheimers_disease_myths_about_alzheimers.asp
http://www.ehso.com/ehshome/alzheimers.htm

- Boiling your wort in an aluminum pot will cause off-flavours in your beer. FALSE. Simply boiling a batch of wort will not remove enough metal from your aluminum pot to get into your beer and cause metallic off flavours, particularly if you build up a passive oxide layer inside the pot first. For new pots, this is easily achieved by either boiling the pot full of water for 30 mins to one hour, or by putting it in your oven for 10 mins at 350 F.

- Aluminum pots have very thin walls, and are not suitable for a boil kettle, particularly if you want to install a ball valve. FALSE. Thin- and thick-walled pots are made from both aluminum and stainless steel. The material they are made from is much less relevant that the thickness of the pot.

- Aluminum pots will react with very acidic materials, and wort is acidic. NOT REALLY. Wort isn’t acidic enough to cause a problem with an aluminum pot. In fact, both SS and aluminum are quite resistant to acidic materials, and you need to be concerned more about highly alkaline (i.e. basic or high pH) materials with your pots.

- Aluminum pots are simply not as durable as SS pots, so why bother, plus they will scratch easily and harbor bacteria. PERHAPS, BUT... Both aluminum and SS are durable enough for homebrewing if you are willing to invest just a small amount of care for your equipment. You simply aren’t going to wear out an aluminum pot in your brewing lifetime, so this is a moot argument. Furthermore, scratches aren’t really a concern with a kettle since the heat of the boil is going to sanitize it anyways.

The Bottom Line:
You can’t go wrong with a quality stainless steel pot, and they are a tried-and-true solution for lots of homebrewers. Yet, aluminum is a viable alternative that is much less expensive than SS. In fact, you can generally purchase a larger and heavier aluminum pot compared to the equivalently priced SS pot. In homebrewing, I guarantee you will really appreciate having a larger pot that is heavy and conducts heat well, speeding our boiling and cooling times and reducing scorching. In my mind, this far outweighs the cosmetic appeal and somewhat higher durability of a SS pot.


I have probably missed a few important points, but would be happy to ammend this post to keep it thorough and accurate.
__________________

 

[GnenieGone]

For the finishing note. The stout that tasted like a coin after boil ended up being the best beer I've made. Made about 10 since with no hint of metal.