Sour Apple Smell on Floating Dip Tubes in Fermentors

[micraftbeer]

I've just recently started using two fermentors that have a floating dip tube (FermZilla All Rounder and BrewBuilt X1). I've used these before in my cold crash keg (where I let the beer sit after fermentor for 2-3 days in 35F fridge before transferring to serving keg). In my most recent brews in these fermentors, both of the flexible tubing of the dip tube absorbed a strong sour apple smell. Completely different fermentors with completely different beers and yeast. I noticed the one, and found the surface of the silicone hose felt rough and had a slight orange hue to it. The other one, had the exact same smell, but didn't have the rough surface.

Has anyone run into this when using the floating dip tubes in fermentors? I don't know if there's a trick to cleaning them afterwards to make sure all this stuff gets off/out?

 

[micraftbeer]

It's maybe unethical to bump your own post, but I'm doing it anyway. This apple smell is so prominent, I've gotta think that anyone else that's using silicone in a fermentor (floating dip tube) has either experienced this, or has a post-ferment cleaning process that I'm not doing.

 

[tripeland]

I use silicone floating dip tubes and do notice they hold onto a smell, even after cleaning with pbw. I’ve used the same line for several beers (obviously cleaning the line in between batches) and not had any issues with infection if that’s what you’re concerned about.
I would not store the silicone tubes in starsan as it will cause the silicone to become brittle and leave microcracks over time, which would be difficult to clean. The embrittlement is worsened when the silicone is stretched over a fitting like a float piece.
The silicone lines can be washed with pbw, left hanging to dry, stored dry, and then a quick starsan rinse when you are ready to use it again.

 

[micraftbeer]

Thanks, @tripeland . After the first batch I did a rinse with One Step / EZ Clean, got the aroma, and decided to change the tubing. Next batch I did a soak in Star San for about 30 minutes, and found that didn't eliminate it.

I've now got a soak in One Step going where I checked at 8 hours, still had the aroma. Now heading towards 24 hours and I'll check again.

It sounds like maybe I just need to let the tubing air out after cleaning, in between brews rather than put back in fermentor with the lid on.

 

[tripeland]

Silicone will absorb aromas and can discolour fairly easily. As long as you keep it clean it is fine. Starsan will only work on a clean surface, no need to soak. Storing dry also means you don’t need to worry about mold.

 

[micraftbeer]

I noticed after the 24-hour soak in EZ Clean One Step, the aroma was quite a bit less. But then I think the kicker was I let this sit out and completely air dry, rather than dry inside the fermentor with the lid cracked open. I guess the increased air exposure helped dissipate the sour apples.