Purple Black Trub

[daveafrank]

Racked an IPA to a keg yesterday and after popping off the lid of my brewbucket, I noticed that the hop sludge/trub that was above the beer line(exposed to whatever gas was in the headspace) turned a purplish/dark grey brown color.

I can upload a photo if it helps...anyone had an explanation for this? Beer looked, smelled and tasted great. The fermenter smelled great as well.

This was fermented, dry-hopped with loose pellets in primary(skipped secondary), and then crash cooled for 2 days.

 

[daveafrank]

Photos

 

[Yooper]

I have no idea! Does oxygen + stainless + trub somehow react and make that color? That's a lot of headspace, so that's my guess anyway!

 

[TheCanisDirus]

No idea what that is... but thanks for the new band name!

 

[daveafrank]

No idea what that is... but thanks for the new band name!

Hah!

 

[Yooper]

I was just thinking, after cleaning out my fridge, that some things do turn, er, dark, in the presence of oxygen. Generally, it's not purple, but I wonder if green krausen + black oxidation = purple?

 

[daveafrank]

I was just thinking, after cleaning out my fridge, that some things do turn, er, dark, in the presence of oxygen. Generally, it's not purple, but I wonder if green krausen + black oxidation = purple?

I was afraid it was oxygen. I dumped the pellets in after primary fermentation died down and then got some airlock activity again as they off-gassed. Kind of expected the headspace to be filled with CO2, especially close to the surface of the beer.

 

[Yooper]

I was afraid it was oxygen. I dumped the pellets in after primary fermentation died down and then got some airlock activity again as they off-gassed. Kind of expected the headspace to be filled with CO2, especially close to the surface of the beer.

Well, headspace is never filled completely with c02, as the laws of physics (Ideal Gas Law) do come into play.

But generally, short term with a lot of headspace is ok of course.