Metallic Taste post kegging

[Rob2010SS]

We've had a couple of beers take on a slight metallic/tin like taste after they make it to the keg. It doesn't come on right after kegging and it's not every glass even. I have not noticed it on every beer, it's only been a couple - the latest is a blonde ale and I did notice it on a brown ale some time ago.

Because it shows up after kegging, I would think it would have to do with something I'm doing on that end. All of our kegs go through a clean with oxyclean, a thorough rinse, and then a sanitize where we fill it up to the top with sanitizer and push it out with CO2 (all cleaning done with the SSBT Keg Washer). We carbonate in the unitank and then closed transfer from the tank to the kegs. Because we only have a 2 tap kegerator, 1 keg will usually go into the kegerator and 2 will sit out at room temp until the kegerator has an open spot. We don't usually notice a tin like taste until after the first keg is gone.

Any thoughts on what to look at?

 

[jtratcliff]

 

[TheMadKing]

Sounds like a slight infection somewhere in your process that's doing its damage while the kegs sit warm. Most likely contaminated yeast, or fermenter or transfer lines

 

[day_trippr]

Any chance you're picking up some yeast during the dispensing?

Cheers!

 

[TheMadKing]

Any chance you're picking up some yeast during the dispensing?

Cheers!

Doh.. Didn't even think of that. Autolyzed yeast can taste metallic, you're spot on.

 

[Rob2010SS]

I suppose it’s possible. And actually that might make sense with this latest beer. The first keg I filled, I forgot to clear the racking port on the tank before filling. So I got maybe 2 seconds of flow of yeast into the keg. The second keg was all clear beer so that was the first one in the kegerator while the first filled keg sat out at room temp for 5 days. So that would make sense.

I feel a little dumb for asking this question but what causes the autolyzed yeast? I’ve had numerous commercial beers with yeast in them and don’t recall tasting that metallic flavor. What’s the difference here?

 

[TheMadKing]

I suppose it’s possible. And actually that might make sense with this latest beer. The first keg I filled, I forgot to clear the racking port on the tank before filling. So I got maybe 2 seconds of flow of yeast into the keg. The second keg was all clear beer so that was the first one in the kegerator while the first filled keg sat out at room temp for 5 days. So that would make sense.

I feel a little dumb for asking this question but what causes the autolyzed yeast? I’ve had numerous commercial beers with yeast in them and don’t recall tasting that metallic flavor. What’s the difference here?

You drink a keg in 5 days? Not judging.. But damn!

Sitting out warm under pressure could do it. Most commercial beers that are unfiltered are also kept cold as much as possible. I've definitely gotten metallic or bloody flavor from a barleywine that I aged in a carboy at room temperature for a few months.

5 days is pretty quick though and doesn't seem long enough for that to be a major issue

 

[Rob2010SS]

You drink a keg in 5 days? Not judging.. But damn!

Sitting out warm under pressure could do it. Most commercial beers that are unfiltered are also kept cold as much as possible. I've definitely gotten metallic or bloody flavor from a barleywine that I aged in a carboy at room temperature for a few months.

5 days is pretty quick though and doesn't seem long enough for that to be a major issue

Ha, we’ve only done that once. Our record for a corny keg is 4 days between me, my wife, my mom and her mom. But no this was our howler club. We have 62 ppl in a club that whenever they want fills of our beer, they bring their howler to us and we fill it.
The kegs were definitely under pressure too. They were left at 12 psi after filling but after being at room temp the pressures were significantly higher when I put the other kegs in the kegerator. So this is something I need to work on in my process

 

[day_trippr]

[...]what causes the autolyzed yeast? I’ve had numerous commercial beers with yeast in them and don’t recall tasting that metallic flavor. What’s the difference here?

I do not believe yeast need to be autolyzed to convey a metallic character. I am nearly certain I have never had yeast subject to a time/temperature/pressure corner required to lose cellular integrity and spew their guts out - I don't have any fermenter that could produce the pressure, and aside from one barley wine and a bunch of imperial stout brews, I've never let a beer sit on the yeast for more than a couple of weeks, and every brew is under tight BrewPi temperature control.

Yet, on occasion over the couple of decades have experienced the metallic note. That has always been the result of mishandling or simply rushing a keg to the tap such that the yeast provided an unwanted character contribution. In the fullness of time, those all abated and life was good

I've had at least a half dozen kegs over the years that on first, second, even third pours tasted like "might be my first dumper" only to resolve favorably...

Cheers!]

 

[Beermeister32]

Unless it is an IPA, I prefer to age out my kegs about 90 days. A lot of issues will improve or go away after this time. I don’t like rushing beer to the tap.

Since you go through kegs at a pretty fast rate, I’d suggest you find a BIG refrigerator to begin storing finished beer kegs. I lager mine at 34F. Also I’d put about 4-6 more kegs in rotation and let the beer age out and do it’s thing. Crack them open after 90 days!

 

[Rob2010SS]

I do not believe yeast need to be autolyzed to convey a metallic character. I am nearly certain I have never had yeast subject to a time/temperature/pressure corner required to lose cellular integrity and spew their guts out - I don't have any fermenter that could produce the pressure, and aside from one barley wine and a bunch of imperial stout brews, I've never let a beer sit on the yeast for more than a couple of weeks, and every brew is under tight BrewPi temperature control.

Yet, on occasion over the couple of decades have experienced the metallic note. That has always been the result of mishandling or simply rushing a keg to the tap such that the yeast provided an unwanted character contribution. In the fullness of time, those all abated and life was good

I've had at least a half dozen kegs over the years that on first, second, even third pours tasted like "might be my first dumper" only to resolve favorably...

Cheers!]

Looks like I need to do some reading on it to figure out what I'm doing to cause it.

With this blonde ale, we brewed it on 7/11. Took gravity readings on 7/19 and 7/21, stable at 1.011. Began crashing on 7/21. Once the beer was down to 35F, started fining with Biofine. This took a bit of time. Did a couple of yeast dumps but perhaps I didn't dump enough yeast? There was still a bit of yeast in the cone that could have been dumped. Kegged it up on 8/11 after it was carbed via the carb stone. Keg #1 and #3 got a bit of yeast in there that I figured would just drop out. Perhaps that caused it? Not sure... Keg #2 didn't get any yeast and never had the metallic flavor, but again, this was empty in 5 days.

Thoughts?

 

[Rob2010SS]

Just read a few things on autolysis and it doesn't sound like that's what I'm experiencing... No where have I seen it documented that autolysis can cause that flavor (although, I've only been briefly looking...).

However, I found this...

https://beerandbrewing.com/off-flavor-of-the-week-metallic/
Interesting read...

All of my equipment is stainless, except for my CFC. That's copper.

I'm brewing with RO water, but the water comes from our well. The TDS reading on the RO system is still pretty low so didn't think I needed to change filters yet, but maybe?

I'll keep looking but we'll see what i come up with.

 

[TheMadKing]

Just read a few things on autolysis and it doesn't sound like that's what I'm experiencing... No where have I seen it documented that autolysis can cause that flavor (although, I've only been briefly looking...).

However, I found this...

https://beerandbrewing.com/off-flavor-of-the-week-metallic/
Interesting read...

All of my equipment is stainless, except for my CFC. That's copper.

I'm brewing with RO water, but the water comes from our well. The TDS reading on the RO system is still pretty low so didn't think I needed to change filters yet, but maybe?

I'll keep looking but we'll see what i come up with.

You'll see the descriptor as "meaty" or "bloody" but people can perceive both of those as metallic

Have you scrubbed you stainless with an abrasive pad recently? It's possible to scrape off the oxide layer of stainless just like any other metal

 

[Rob2010SS]

You'll see the descriptor as "meaty" or "bloody" but people can perceive both of those as metallic

Have you scrubbed you stainless with an abrasive pad recently? It's possible to scrape off the oxide layer of stainless just like any other metal

I do use a dish sponge to clean the mash tun and the boil kettle after every brew. Specifically this one and I use the green side. I don't go crazy with it and scrub the crap out of it, but none the less, it is slightly abrasive...

I had read on beer and brewing that stainless won't leech into the beer. However, doing a quick search, there's some contradictory info out there that states it can.

The plot thickens...

 

[jtratcliff]

Stainless should self-passivate ...

http://howtobrew.com/book/appendices/appendix-b/passivating-stainless-steel

tldr;

But you don't need a nitric acid bath to passivate. The key is to clean the stainless steel to bare metal. Once the metal is clean, the oxygen in the atmosphere will reform the protective chromium oxides instantly. The steel will nearly as passivated as if it was dipped in acid. Nitric acid passivation creates a more chromium-rich passive surface, but is not necessary for brewing use.

 

[Beermeister32]

I’d use the Blue Scotch Brite, it is non-abrasive. We used to use the green Scotch Brite to make brushed stainless panels, so it definitely could be your issue.

 

[TheMadKing]

I do use a dish sponge to clean the mash tun and the boil kettle after every brew. Specifically this one and I use the green side. I don't go crazy with it and scrub the crap out of it, but none the less, it is slightly abrasive...

View attachment 740334

I had read on beer and brewing that stainless won't leech into the beer. However, doing a quick search, there's some contradictory info out there that states it can.

The plot thickens...

I use the same thing but I clean with barkeepers friend which is oxalic acid and helps passivate

I don't think this is your issue necessarily, stainless is pretty easy to maintain, and as posted above does self passivate, but its possible. Some lower grades of stainless don't have a homogeneous grain structure so you can end up with uneven nickel oxide layers. Have you ever noticed any brown or white spots on your stainless?

 

[Rob2010SS]

I use the same thing but I clean with barkeepers friend which is oxalic acid and helps passivate

I don't think this is your issue necessarily, stainless is pretty easy to maintain, and as posted above does self passivate, but its possible. Some lower grades of stainless don't have a homogeneous grain structure so you can end up with uneven nickel oxide layers. Have you ever noticed any brown or white spots on your stainless?

I've never noticed white/brown spots in my MT or BK. However, the HLT gets them occasionally. I don't rip that apart and clean it every brew as it only holds water. I just wipe the inside of it out with a rag. But when I say it gets a brown spot occasionally, I'm talking small, MAYBE .25" dia. spot.

 

[IslandLizard]

All of our kegs go through a clean with oxyclean, a thorough rinse, and then a sanitize

I'm still thinking a keg infection of some sort.
Do you rinse the kegs out before putting on the washer?

How sure are you the washer, using only Oxiclean gets them clean enough? Why not use some (20-30%) Sodium Metasilicate (TSP/90) or TSP mixed in, effectively creating homemade PBW? Are you washing them with hot detergent or cold?

 

[Rob2010SS]

I'm still thinking a keg infection of some sort.
Do you rinse the kegs out before putting on the washer?

How sure are you the washer, using only Oxiclean gets them clean enough? Why not use some (20-30%) Sodium Metasilicate (TSP/90) or TSP mixed in, effectively creating homemade PBW? Are you washing them with hot detergent or cold?

But if it was an infection, it would affect the entire keg, no? Like it said, it's not even present in every glass which is the weirdest part.

My process for washing the kegs is to use 135F water and rinse out the kegs. I put a little water in, close it up, shake it around and dump. Do that a couple of times.

Then I hook up the keg washer. Again using 135F water (max for the keg washer is 140F) i let the Oxyclean run through there for 20 min or so. Then I move the keg and keg washer assembly to a hot water bucket (135F) and rinse for ~10 min. Then the kegs get filled 100% with saniclean and purged with CO2.

I am curious though on the infection standpoint. Let's say it were an infection. What kind of infection causes metallic flavors? Just to be clear, I'm not being a smart ass. I'm legit asking because I am no expert in any of this.

 

[TheMadKing]

But if it was an infection, it would affect the entire keg, no? Like it said, it's not even present in every glass which is the weirdest part.

My process for washing the kegs is to use 135F water and rinse out the kegs. I put a little water in, close it up, shake it around and dump. Do that a couple of times.

Then I hook up the keg washer. Again using 135F water (max for the keg washer is 140F) i let the Oxyclean run through there for 20 min or so. Then I move the keg and keg washer assembly to a hot water bucket (135F) and rinse for ~10 min. Then the kegs get filled 100% with saniclean and purged with CO2.

I am curious though on the infection standpoint. Let's say it were an infection. What kind of infection causes metallic flavors? Just to be clear, I'm not being a smart ass. I'm legit asking because I am no expert in any of this.

So true "metallic" off flavor is more of a mouthfeel than a flavor. It should make you salivate and feel "thin". It should also be readily apparent in the smell if you take a little beer and rub it on the back of your hand to warm it up.

If that is NOT the case, then most likely what you are describing as "metallic" might be better described using other descriptors such as smokey, tart, astringent, or thin mouthfeel. Any of those most definitely can be caused by an infection.

So we have to use a broad net when we are trying to help troubleshoot over the internet, since what you describe as metallic, I might easily describe as tart. It's all a matter of common language

 

[Rob2010SS]

So true "metallic" off flavor is more of a mouthfeel than a flavor. It should make you salivate and feel "thin". It should also be readily apparent in the smell if you take a little beer and rub it on the back of your hand to warm it up.

If that is NOT the case, then most likely what you are describing as "metallic" might be better described using other descriptors such as smokey, tart, astringent, or thin mouthfeel. Any of those most definitely can be caused by an infection.

So we have to use a broad net when we are trying to help troubleshoot over the internet, since what you describe as metallic, I might easily describe as tart. It's all a matter of common language

No, it is definitely not tart. We make enough sour beers and have had a legit infection in a stout to know that tart is not a descriptor for this.
Smokey is definitely not it either.
Astringent doesn't fit. I've tasted that before as well.

Put a penny in your mouth. That's the taste I'm describing. Quite literally, metallic.

I was drinking it last night and the flavor wasn't there. I'll try and do more analysis if I pick up on it again. I won't rule out all of the above yet.

 

[IslandLizard]

My process for washing the kegs is to use 135F water and rinse out the kegs. I put a little water in, close it up, shake it around and dump. Do that a couple of times.

Then I hook up the keg washer. Again using 135F water (max for the keg washer is 140F) i let the Oxyclean run through there for 20 min or so. Then I move the keg and keg washer assembly to a hot water bucket (135F) and rinse for ~10 min. Then the kegs get filled 100% with saniclean and purged with CO2.

Your cleaning regimen looks sound. I asked about the pre-rinse as a load of trub can deactivate the cleaner quickly.

The carryover of Oxiclean to your hot wash bucket should be minimal. Depending on how many kegs you run through your hot water rinse, after 4-6 kegs there may be more than just a trace left when you go to the Saniclean purge. Maybe implement a quick rinse with cold water after the Oxiclean cycle, before the final, long hot rinse?

Perhaps add a little bit of acid (e.g., Phosphoric Acid, comes in gallon jugs @85%) to the (long) final rinse, before Saniclean?

But if it was an infection, it would affect the entire keg, no? Like it said, it's not even present in every glass which is the weirdest part.

Yes, an infection would affect the entire keg.
Our taste buds are not that finely honed, after the first sip, or few sips, they adapt quickly to the environment (your glass of beer) and you may not taste it anymore until they get some rest or something resets them. A taste buds reset can be a very personal preference. For example, chewing a small cube of watermelon resets mine very effectively, while commonly advised pretzels or Saltines don't, they totally ruin flavor and mouthfeel perception for me.

The smell organ is much more sensitive than taste buds, yet, all aspects of aroma, flavor, and related sensations go nose to mouth and back, so to speak.

 

[Rob2010SS]

Your cleaning regimen looks sound. I asked about the pre-rinse as a load of trub can deactivate the cleaner quickly.

The carryover of Oxiclean to your hot wash bucket should be minimal. Depending on how many kegs you run through your hot water rinse, after 4-6 kegs there may be more than just a trace left when you go to the Saniclean purge. Maybe implement a quick rinse with cold water after the Oxiclean cycle, before the final, long hot rinse?

Perhaps add a little bit of acid (e.g., Phosphoric Acid, comes in gallon jugs @85%) to the (long) final rinse, before Saniclean?


Yes, an infection would affect the entire keg.
Our taste buds are not that finely honed, after the first sip, or few sips, they adapt quickly to the environment (your glass of beer) and you may not taste it anymore until they get some rest or something resets them. A taste buds reset can be a very personal preference. For example, chewing a small cube of watermelon resets mine very effectively, while commonly advised pretzels or Saltines don't, they totally ruin flavor and mouthfeel perception for me.

The smell organ is much more sensitive than taste buds, yet, all aspects of aroma, flavor, and related sensations go nose to mouth and back, so to speak.

For the hot water rinse, I refresh the bucket for every keg. Only 1 keg goes through the hot water bucket. I'll look into the phosphoric acid. Thanks!

That's interesting on the watermelon. I may have to give that a shot some time!

EDIT: Just to clarify, it's a fresh bucket of oxy for each keg and a fresh hot water rinse for each keg.

 

[Vale71]

So true "metallic" off flavor is more of a mouthfeel than a flavor. It should make you salivate and feel "thin". It should also be readily apparent in the smell if you take a little beer and rub it on the back of your hand to warm it up.

+1 on that suggestion. If there are actually Fe+ ions in the beer they will react with your skin's oils and give off an incredibly strong and unmistakable metallic smell.

 

[Rob2010SS]

+1 on thai suggestion. If there are actually Fe+ ions in the beer they will react with your skin's oils and give off an incredibly strong and unmistakable metallic smell.

Interesting. I'll give it a shot!

 

[TheMadKing]

I also just did a little more looking and it looks like hydrolized lipids can also throw a metallic flavor. https://pubs.acs.org/doi/pdf/10.1021/bk-1994-0558.ch001

Here's another theory to throw out:

If you got a good amount of trub from the kettle into your fermenter and a little oxidation, those lipids could be settling to the bottom with the yeast and when you pull a slug out of the bottom of the keg that's what you're tasting. That would explain why it's intermittent

Alternatively, if you have some old malt that you've been using that could be the source of your issue as well. Do all of the metallic beers have a single grain in common? And do all of your non-metallic beers lack that grain?

 

[Lazybeat]

@Rob2010SS hey there, I hate to bring up an old thread as I know it's not great etiquette but I'm having this exact problem and wondered if you solved it? It seems that the first pour or 2 are fine and then the metallic taste comes through.. was it a passivation issue in the end? Currently waiting for more co2 to arrive to carry on experimenting. What a PITA this problem is!

Cheers

 

[Rob2010SS]

@Rob2010SS hey there, I hate to bring up an old thread as I know it's not great etiquette but I'm having this exact problem and wondered if you solved it? It seems that the first pour or 2 are fine and then the metallic taste comes through.. was it a passivation issue in the end? Currently waiting for more co2 to arrive to carry on experimenting. What a PITA this problem is!

Cheers

Hey man. Sorry for the late reply.

I never did figure it out exactly. Possibly narrowed it down though …?

We moved to canning everything. Since our move to cans, have not had the issue at all. So it was something with the kegs or the kegging process. Not sure what it was though.

However, we did buy a small brand new keg to do samples out of before people buy. I can say that THAT keg doesn’t have the issue either. So not really sure what was going on.

 

[Broken Crow]

Just out of curiousity: Were you using stainless or chrome-plated brass shanks and or taps?

 

[Rob2010SS]

We use an insignia kegerator. We replaced our taps with Intertaps, but we had never replaced the shanks. However, we’re still using those shanks at the brewery and no issues. I ran new beverage lines and the shanks appear to be stainless and I believe the intertap faucets are stainless as well

 

[Knightshade]

Picked this up at an "off-flavors" tasting class I attended sometime last year. Sadly..at my goto LHBS that closed down. He tried to sell it, landlord wasn't interested. Sucks.

At any rate..try the smell test. Put some beer on the back of your hand and if you get that same metallic smell that you're tasting, this is it.

 

[Rob2010SS]

Picked this up at an "off-flavors" tasting class I attended sometime last year. Sadly..at my goto LHBS that closed down. He tried to sell it, landlord wasn't interested. Sucks.

At any rate..try the smell test. Put some beer on the back of your hand and if you get that same metallic smell that you're tasting, this is it.

View attachment 810158

Really good info! Thanks for sharing that!!

 

[Knightshade]

I wish I had the damn legend to those symbols. This off flavor was the only one w/that hand symbol, so that is why I can recall it specifically. If I was to guess, these would be the symbols in the following order, left to right.

1. Glass at arm's length, bring to your nose and inhale
2. Same as above, but follow a downward trajectory path. (I know some are taught to inhale as the glass is coming towards your nose and bring the glass outwards to arms length though..so?? *shrug*)
3. Finger in glass...no flipping idea
4. Back of hand thing
5. Believe this is to indicate 3-5 short sniffs.

 

[Brooothru]

Picked this up at an "off-flavors" tasting class I attended sometime last year. Sadly..at my goto LHBS that closed down. He tried to sell it, landlord wasn't interested. Sucks.

At any rate..try the smell test. Put some beer on the back of your hand and if you get that same metallic smell that you're tasting, this is it.

View attachment 810158

Ahah! Iron sulfate. Isn’t that the taste you get if you moisten the tip of a styptic pencil with the tip of your tongue?

Ask me how that oral sensation is so recent in my memory. Damned razor.