Defect Diagnosis

Ingredients
1

I recently brewed a gluten free Pale Ale using the Ground Breaker Brewing recipe (with different hops) that was posted a few months ago. I racked to keg last night and something was clearly off.

I normally brew all grain, so a partial mash brew seemed fun with the intent to make a GF ale for a few gluten sensitive friends that don’t drink beer. Brew day went without issue. I started with RO water, added a little gypsum and calcium chloride to suit the style. Wort pH was 5.35 before the boil. The wort tasted fine going into the fermenter. I used US-05 which became active about 12 hours after pitching.  I kept fermentation at 66-67 for 5-6 days and ramped up to 68-69 after activity seemed to subside. OG was 1.052 and FG was 1.009 after 11 days.  Fermentation seemed slower that usual, but steady.

After racking to keg and adding dry hops, I evaluated a sample from the fermenter. Appearance was as expected (light gold / orange).  Aroma was earthy with some rubber in there!  Maybe a touch of phenolic.  I did not get band aids directly, but maybe there is some of that in there too.  Flavor matches the aroma if that makes any sense. I also noticed that there was a thick layer of very loosely flocculated yeast at the bottom of the fermenter. I think I lost at least .75 gal during racking to keg. I have never seen that with US-05 or from the 4-5 other liquid strains I typically use. Photos at link below - note that I did seem to transfer some hop matter from the boil kettle because my revised whirlpool method did not work as planned to collect trub in the middle.

https://photos.app.goo.gl/evJsxtPJR37jVf052

My question is if anyone has experienced this type of defect and/or the yeast flocculation behavior.  I suspect that I got an infection somewhere, despite my usual liberal use of Star-San and extensive equipment cleaning. Maybe my RO water source gave me some chlorine? I’m trying not to blame the GF ingredients :slight_smile: but the next batch is likely go back to my usual recipes.  I’m going to let this one sit in the keg for 1-2 weeks and then likely dump it, but it would be nice to understand what may have happened.

2

Were your ferment temps ambient or actual fermenter temp?

3

They are thermowell temps inside the wort.  I use an external chiller and cooling coil inside the fermenter.

4

It could be wild yeast contamination. I had some yeast over a year ago that I had stored from a previous batch that ruined two batches before I figured it out. They both had a rubber, phenolic taste that was unpleasant. I had to dump both batches. You might want to switch sanitizers to idophor which works better against wild yeast.

5

Thanks!  Maybe it’s time to replace o-rings and gaskets in the fermenter.  I will get some idophor and give that a try too before the next round.