Chasing off-flavors

[nickbarley]

I'm a BIAB brewer and corny keg fermenter/server. I've been getting an acidic, sour, plastic-like, rubbery off-flavor in a few of my batches now, and it's very frustrating to troubleshoot. This flavor appears post-fermentation, when I've kegged and force carbonated my beer at around 13-14 psi. I ferment and serve out of a 5 gal corny keg. During fermentation I have a blow-off tube going into a jar full of water and star-san. I typically allow my batches to ferment for about 7-9 days before cold-crashing to 40 F and force carbonating at 14 psi for 2-3 days.

The samples I take are with a picnic tap with pvc tubing. I just run some star-san through the picnic tap before attaching it to my liquid out post. Before fermenting, I disassemble the keg components, and soak them in hot water and star-san for a couple hours before dumping the wort and pitching my yeast.

I do use my city's tap water, which does have chlorine/chloramine, but I add 1/4 of a campden tablet to my water prior to mashing in.

My question is: could this off-flavor be an infection, chlorophenols, autolysis, bad keg lines (liquid/gas), astringency, or just ingredients?

I would be glad to post my grain bill and brew day practices to see if that gleans any information. Any help would be greatly appreciated!

 

[nickbarley]

I'm tasting my latest batch right now (hefeweizen using 3068 yeast), and there is a distinct medicinal flavor when I swish it around in my mouth. The flavor lasts on my tongue even afterwards. I searched around and see that chlorinated water will give this off-flavor.

I have an extract batch I'm fermenting right now that I brewed with R.O water. Hopefully, that will not have that off-flavor. If it does, I might try replacing all of my soft tubing and use my glass carboy to try and isolate any fermentation/sanitation issues.

 

[nickbarley]

Update: after giving this batch 20 days to condition, I tasted a sample this morning and... vomit. Yup, it was an infection for sure. Nuking all of my plastic tubing and bleaching my fermenters. So frustrating, but it's good to know it's a sanitation issue because that can be easily fixed! (hopefully)

 

[hottpeper13]

Disassemble your valves and disconnects and see if any brown goo is there.

 

[nickbarley]

Disassemble your valves and disconnects and see if any brown goo is there.

You're spot on. I disassembled my picnic tap and sure enough there was this rusty/brown build up on the metal barb of the liquid disconnect. I just threw that away. I'm not 100% sure if it was rust, but I am not taking any chances. Thanks