Odour in stainless steel

[MrTimV]

I'm running out of ideas so I'm hoping someone here will be able to point me in the right direction.
I've got two brewing system, a half barrel and a 5G, so something to keep in mind is that my issue lies only with the half barrel system, I've done multiple batches during the time frame of my story in the 5G that have turned out great.
I've used my half barrel system about once a month, process always the same, transfer out, clean off large debris, run hot PBW, rinse, through CIP and spray down with Star San, let dry.
The last two batches have had an off flavour, I'd describe as kinda chemical tasting, bit of sulfur aroma.
The first batch I didn't blame fermenter, was a hefeweizen that I actually racked out half of to add fruit too and that half turned out great. Unfortunately my kegerator died so the hefe was treated as normal so I blamed the few miss steps caused by some equipment failure. It also though did a weird stratifying thing in the cans I've never had it do before, where if you didn't roll the can to essentially stir everything up, th etop half of the can poured out like a light lager. The bottom half looked like the usual cloudy hefe.
Anyways as I said, I blamed process at packaging, particularly as the fruited half turned out great.
Then I brewed a Kolsch and it had the same kinda of odours and flavours, but much more pronounced. It's also a bit hazy, despite being crashed for a few days, gelatin and sitting in th ekeg at 38F for a week before trying a glasss. Pulled a glass from another keg, same issues but slightly less pronounced. Haven't tried the 3rd keg yet.

Anyways started ripping apart the fermenter (SS Brewtech Half Barrel Chronical), they are butterfly valves but taken them apart, scrubbed out, soaked in hot PBW, rinsed, star san individually etc. actually let everything soak in heated up star san (was about 140F) for about 9 hours yesterday, hadn't mean to leave it that long but I got sidetracked and figured more time won't hurt. May not do any good, but certainly won't hurt.
Anyways all this to say, I'm comfortable with how I have my parts cleaned and sanitized, however even with everything removed, the fermenter still has an aroma, I can't quite place/don't know really how to describe. Air outs very quickly when I take the lid off. It doesn't small bad at all, I asked my wife to take a smell as well and she couldn't place it either, I'd say kind of metallic tangy.

So after all this long description, what I'm wondering, as I don't have a basis for comparison, is that simply how it smells normally and I'm chasing ghosts? Any extra steps you'd recommend? I'm boiling the valves and fittings today regardless as a precaution.

 

[Dr_Jeff]

All of my stainless, when clean, has no smell.

 

[The_Bishop]

If you suspect an infection of some sort, break it all down and give it a wash in fresh made iodophor, it kills far more than star san does.

 

[FrostyBeach]

a metallic smell sounds like you scrubbed it too much and may need to help it passivate. You could try a citric acid solution, it's cheap. You need a 4 to 10% solution. You don't have to fill the vessel with it just keep it wet for 30 mins or so and then air dry and rinse.

 

[Bilsch]

The last two batches have had an off flavour, I'd describe as kinda chemical tasting, bit of sulfur aroma.
The first batch I didn't blame fermenter, was a hefeweizen that I actually racked out half of to add fruit too and that half turned out great. Unfortunately my kegerator died so the hefe was treated as normal so I blamed the few miss steps caused by some equipment failure. It also though did a weird stratifying thing in the cans I've never had it do before, where if you didn't roll the can to essentially stir everything up, th etop half of the can poured out like a light lager. The bottom half looked like the usual cloudy hefe.

Anyways all this to say, I'm comfortable with how I have my parts cleaned and sanitized, however even with everything removed, the fermenter still has an aroma, I can't quite place/don't know really how to describe. Air outs very quickly when I take the lid off. It doesn't small bad at all, I asked my wife to take a smell as well and she couldn't place it either, I'd say kind of metallic tangy.

There are some cutting, stamping and machining oils that are very persistent and take quite some effort to remove. I would hit it with a hot ~180f or so 5% sodium hydroxide solution and let it soak for at least several hours, better over night. The rinse well and proceed to passivation with a 4% citric acid solution at 160-180f for a couple hours. If you do this remember to stack all your other stainless equipment that will fit in the kettle and do it all at the same time. This is the commercial gold standard method for de-greasing, cleaning and passivization your stainless.

 

[RPh_Guy]

spray down with Star San, let dry.

There's no benefit to applying Star San before storage.
After the alkaline cycle it's best to use an acid rinse and then water rinse. This helps remove inorganic residue, which is not removed by PBW.

chemical tasting, bit of sulfur aroma.

It's also a bit hazy, despite being crashed for a few days, gelatin and sitting in th ekeg at 38F for a week before trying a glasss.

• "Chemical tasting" could be phenols, which is typically from wild microbes (except for select strains such as the hefeweizen yeast, which is phenolic).
• Sulfur aroma is hydrogen sulfide, which is also a microbe-derived off flavor.
• Wild microbes also tend not to flocculate, and cause haze.

Is it just a coincidence all the issues you're describing are potentially caused by contamination?

Another source of chemical taste could be chlorophenols, so make sure you are treating your water appropriately to remove any chloramine.

It also though did a weird stratifying thing in the cans I've never had it do before, where if you didn't roll the can to essentially stir everything up, th etop half of the can poured out like a light lager.

That's completely normal for the yeast to settle with time. In Germany when ordering it you can specify how much yeast you want (e.g. mit hefe).

It doesn't small bad at all, I asked my wife to take a smell as well and she couldn't place it either, I'd say kind of metallic tangy.

It should be rinsed with water before storage, and have basically no smell.

If you suspect an infection of some sort, break it all down and give it a wash in fresh made iodophor, it kills far more than star san does.

1. Iodophor is not a cleanser so it won't help with this problem.
2. Iodophor kills "far more" than Star San? Not really, and even if that were true it wouldn't matter. The PBW would have already killed everything it can reach because it creates hydrogen peroxide, a strong anti-microbial.

a metallic smell sounds like you scrubbed it too much and may need to help it passivate. You could try a citric acid solution, it's cheap. You need a 4 to 10% solution. You don't have to fill the vessel with it just keep it wet for 30 mins or so and then air dry and rinse.

Not a bad idea.
It needs to be heated to at least 140°F, as @Bilsch mentioned, ideally with a 2 hour contact time.
It should be rinsed after the acid, not dried before rinsing.

Cheers

 

[augiedoggy]

star san is an acid^, a mild one but still an acid solution though I agree for regular cleanings, its pointless to use it unless your going to be sanitizing something immediately before use. some people use it for hoses and such before storing damp to prevent mold from growing while drying.
I do not not know if starsan whether mixed as recommended or in a stronger solution will work for passivating but I have wondered if it helps.

Also you never want to use star san or any acid based solution right after oxy or pbw, unless you have rinsed well between so. since one neutralizes the other.

 

[day_trippr]

I don't think phosphoric acid is particularly effective at passivation.
Nitric and citric are recommended, and given citric is cheap and relatively safe to use, that's what I go with...

Cheers!

 

[The_Bishop]

1. Iodophor is not a cleanser so it won't help with this problem.
2. Iodophor kills "far more" than Star San? Not really, and even if that were true it wouldn't matter. The PBW would have already killed everything it can reach because it creates hydrogen peroxide, a strong anti-microbial.

Well, if the equipment is visibly dirty, there's no point in sanitizing. That goes without saying.

As far as effectiveness, star san will not 'kill' yeast or mold due to it's mode of operation, which is acid based.

Iodophor is a halogen based sanitizer and far more broad spectrum. It will reliably kill wild yeast, mold, bacteria, etc. given proper concentration (follow the mixing instructions) and contact time. It's biggest drawback is that you can't keep it in a spray bottle as the iodine will make it's way out the the liquid as a gas and it will lose it's effectiveness so it's best to make what you need fresh when you need to use it.

 

[RPh_Guy]

star san will not 'kill' yeast

That's a common myth, with no science to back it up. The DBSA is the active ingredient, and it has been shown effective against yeast.

 

[BruceH]

Help me out here, Idophor is iodine, correct? Similar to the iodine used prior to medical procedures to kill everything? Smells the same, looks the same to me.

To move on to the stainless smell. My brew kettle is stainless, I don't know the exact composition. I clean prior to storage. However, prior to use there is a metallic odor. Scrubbing with a greenie pad and rinsing gets rid of it. I've always written it off to not having a mirror finish on the kettle (kitchen pots don't get this odor). This in turn causes some kind of corrosion I can't place. Just a theory but in any case whatever it is that forms easily scrubs out and rinses away.

One more thought. I can smell mildew in minute concentrations. Over my life I've observed that many people can't smell a mildew infection in their clothing or household. Is it possible that this stainless odor is something that only a certain percentage of the population can detect? Kind of like the bitter almonds smell of cyanide?

 

[RPh_Guy]

Help me out here, Idophor is iodine, correct? Similar to the iodine used prior to medical procedures to kill everything? Smells the same, looks the same to me.

To move on to the stainless smell. My brew kettle is stainless, I don't know the exact composition. I clean prior to storage. However, prior to use there is a metallic odor. Scrubbing with a greenie pad and rinsing gets rid of it. I've always written it off to not having a mirror finish on the kettle (kitchen pots don't get this odor). This in turn causes some kind of corrosion I can't place. Just a theory but in any case whatever it is that forms easily scrubs out and rinses away.

One more thought. I can smell mildew in minute concentrations. Over my life I've observed that many people can't smell a mildew infection in their clothing or household. Is it possible that this stainless odor is something that only a certain percentage of the population can detect? Kind of like the bitter almonds smell of cyanide?

I'd be interested to see if you have different results after passivating.

 

[BruceH]

If be interested to see if you have different results after passivating.

Me too, it's next on my list.

 

[day_trippr]

Agreed. Wet iron has a distinct odor, kinda blood-like. If a kettle smells strongly of that I'd suggest a full citric acid treatment.
And if one does that - don't forget to soak whatever other SS stuff one has that might benefit. I recently did some work on my SS IC that necessitated a passivation cycle and used the same liquid to treat my SS hop spider. Both bright as heck afterward - and no hint of iron odor...

Cheers!

 

[The_Bishop]

You should stop scrubbing your kettle with a green scotchbrite pad. The abrasives in the green pad are removing the chromium outer layer that makes stainless... well, stainless.

There are blue scotchbrite pads available, I usually find them in Walmart. They don't have any abrasive embedded in them, just nylon. If you need to knock loose some residue, they work well without harming the vessel.

You could re-passivate the kettle by filling it up to the brim with 130-140f water and somewhere in the neighborhood of 10% by weight citric acid. Another option is the newish spray-bottle barkeeper's friend I've seen lately, it contains citric acid and oxalic acid, along with surfactants. I found it in Home Depot, or you could order it. Works great at removing beerstone from kettles, and the two main ingredients will passivate the stainless kettle. Works great for cleaning up the outside of kegs, too. No abrasives in it, which is a bonus to me.

I'd be willing to bet the odor you have is metallic due to the free iron revealed by the green scrub pad. Re-passivate it either via the spray barkeeper's friend or citric acid, rinse it well and let it air dry. Should do away with the smell.

Bar Keeper's Spray: https://www.amazon.com/Bar-Keepers-Friend-MORE-Spray/dp/B00BRXFQ8A

Blue scotch brite pads: https://www.amazon.com/Scotch-Brite-Non-Scratch-Scour-Pads-3-Pads/dp/B0196H6TKM

 

[The_Bishop]

That's a common myth, with no science to back it up. The DBSA is the active ingredient, and it has been shown effective against yeast.

I didn't phrase it correctly. Star san will kill yeast cells, given enough time and mixed at the proper ratios and at the correct pH.

However, Iodophor works differently. The most succinct quote I found on it states: "Iodine/iodophores attack sulphur-containing molecules. These chemical groups can be found in membrane lipids, cell wall components, and in all proteins. The cells essentially die as a result of having nearly every aspect of their biology (aside from their DNA, which is sulphur-free) destroyed."

The truth of the matter is that Iodophor is much more broad spectrum than Starsan. That doesn't mean Starsan doesn't work, but it's always a wise move to alternate sanitizers from time to time to insure you don't end up with a single-sanitizer-resistant bug in your gear.

 

[RPh_Guy]

Another option is the newish spray-bottle barkeeper's friend I've seen lately, it contains citric acid and oxalic acid, along with surfactants.

Keep in mind it won't passivate at room temperature.

Re: sanitizers...
I'm not questioning the efficacy of Iodophor.
I'm questioning superstitious advice about switching sanitizers or unscientifically trying to make Star San look inadequate. If you're aware of any evidence that there are beer/wine contaminants that can become resistant to Star San, I'd be happy to see it.
Again, hydrogen peroxide is part of a good cleaning process and so there are already multiple anti-microbials in play regardless.

 

[teesherv]

I just got through this same thing, ruined plastic fermenters, couldn’t get the weird metallic smell out of the beer or fermenter. After a frustrating process of elimination, it was my kettle.
Turns out my Stainless steel kettle was not passivated completely. I scrubbed too hard, let hard water air dry on it, pissed of the brewing gods, whatever.
Cleaned and scrubbed with Bar Keeps Friend and then passivated. Lots of suggested methods here to passivate, and just as many arguments for or against each.
Now I am sure dissolve PBW in a separate bucket and pour into kettle, use a soft cloth (no scrub), and not to let hard water air dry on the stainless - towel dry is a PITA but better than what I was dealing with before.
You may have a different reason for your issue, but this worked for me.