Blow off Black Residue

[cnowlan]

I had a look through the forums but couldn't find any information on this particular topic and thought I'd share. In case anyone else has run into this or does in the future.

I ferment in a converted fridge and typically use a blow off tub for the entire primary fermentation. I use starsan in my blow off bottle. I’ve noticed that with some fermentations that I get a black ring that forms on the blow off hose and even on the neck of the clear glass bottle I use. This happens without any Krausen coming out of the blow off tube.

In the latest case I actually changed out the blow off tube and bottle after the height of fermentation where Krausen was coming out of the fermenter.

My primary concern was that this is some sort of biological infection that could put my beer at risk. Took some samples of the black ring and took a look under 400X magnification.

Few other points:
• This stuff by the way is very difficult to wash off even when soaking in PBW.
• The starsan was perfectly clear and was made up recently with RO water.
• There is some discoloration of the starsan solution, goes lightly brown, but still mostly clear
• Tested the pH of the starsan and it was still ~2.5
• This beer is a dunkelwizen being fermented with Wyeast 3068 which does produce some sulfur
• Had this happen before and does seem to impact beer


So it appears to me that this stuff is residual mineral deposit caused when the C02 and other gases from fermentation bubble through the star san (pH of ~2.5). C02 + phosphoric acid -> ?. Or Something sulfur compound related?

My question is has anyone else run into this before? Any other opinions on what this is specifically and is it of any concern?

Here are some pics:
Ferment chamber and blow off set up

Here's the "black ring"

Here is the "gunk" at 400X. In my limited experience this looks mineral and not organic.

 

[jack.herr]

I did a search for this exact thing and found this thread... 6 years after originally posted. I brewed a lager with a WLP lager yeast and found black residue around the blow off container at the completion on fermentation. There was also a black ring at the bottom of the container (containing starsan) where the tube met the bottom. Pain in the ass to clean off. It seemed like it was burned on carbon like BBQ stuff.

 

[mr_lahey]

The original post is pretty much exactly the experience I just had. I used Wyeast 2278 Czech Pil. The beer is only halfway done fermenting, but it smells and tastes fine so far. I was able to get the residue off with some steel wool.

I am going to add a couple pictures to this thread, just for the record:

 

[day_trippr]

Don't know if the Star San is a necessary ingredient to leaving black rings on blow-off hoses, but why are y'all putting sanitizer in a blow-off catch jug anyway?

I stopped doing that years ago because it made the submerged ends of my 1" ID vinyl blow-off tubes slimy.
I don't like "slimy" on anything...and I just don't see "bugs" crawling up a tube
Switched to plain jane tap water. Still have never had an evident infection after 16 years of brewing...

Cheers!

 

[mr_lahey]

but why are y'all putting sanitizer in a blow-off catch jug anyway?

I never really thought about it, I just figured that is what it is supposed to be after reading posts on setting up blow-off tubes

Switched to plain jane tap water. Still have never had an evident infection after 16 years of brewing...

Thats good to know. I may have to change up my procedure. I'm curious, do you use plain water in airlocks as well?

Thanks

 

[day_trippr]

I do use Star San in my S-locks, rationalizing that because they sit above the mouth of the carboys and if something out of scope were to happen (eg: stuck controller Cool relay with resulting suck-back) would feel better about it than water.

I suppose the same logic might justify using Star San in a catch vessel, but suck back of that volume would be an issue on its own...

Cheers!

 

[Vale71]

Sanitation considerations aside the black, resin-like deposits are just that, i.e. oxidized hop resins. Oxygen exposure is a pre-requisite to their formation so you'll only find them in a blow-off bucket or a non-airtight fermenter. In a pressurized fermenter that is never opened after fermentation starts the worst you can find in the Kräusen ring is dried-off yeast which requires no scrubbing and can be cleaned-in-place.

 

[mr_lahey]

the black, resin-like deposits are just that, i.e. oxidized hop resins.

I'm satisfied with this explanation.

I switched to an s-type airlock and I'm also seeing the residue in two places... Just adding the pic to this thread for documentation purposes.

This is going to be trickier to clean.

 

[Dog House Brew]

I use 3 piece locks and use cheap vodka. I got tired of them getting crap in them, mostly blow off years ago. I agree with using tap water in my blow-off jugs,