Tuesday, May 14, 2019

How A Bacterial Infection in Your Beer Can Ruin Your Weekend

Late last year, I started brewing various British beer styles to become familiar with them. My goal was to have a collection of beers I could enter into this year's SODZ British Beer Fest homebrew competition. I'd managed to brew an Ordinary Bitter, a Scottish 80 Shilling, Irish Red Ale, British Brown Ale, and others.  I entered four of these into the Barley's competition this year. Two came back with terrible scores because they gushed out of the bottle on the judges. 

Having brewed for several years now, and having not varied my sanitation practices much, I was in complete denial when the Barley's judges suggested that the beer had been infected. When the same thing happened with two different beers at the SODZ competition, I could no longer deny it. I had a bacterial infection somewhere. But where?

Given my brewing process, I had the following candidates:
  • Brewing System:  If the plumbing inside either the PicoBrew Zymatic or the Brewie+ became infected, specifically on the cold side, then the beer might be infected going into the fermenter. However, this seemed unlikely. I tentatively ruled it out.
  • Fermenter:  If one or more fermenters had an infection that survived a PBW clean and Star San sanitization, that could be passed on to the beer.  If this was the cause of my infection, it would impact any beer brewed in that fermenter.  A good indicator would be if I could identify infected batches vs. uninfected ones, and trace that back to a fermenter.
  • Bottling Wand:  I only owned two bottling wands. If one of those was infected, it would infect every bottle filled with that wand, but not batches filled from the other wand (unless both were infected).  
  • Carbonation Drops:  I had been picking these up by hand and placing them into the bottles with my fingers (which had been washed and spent a lot of time in Star San). There was a small chance this could have infected the tablets and then the bottle. If this was the case, every batch I bottled would be infected.
  • Bottle Caps:  This seemed unlikely. In general, my caps soak in Star San until I pull them out to put them on the bottle. I can't rule it out, but it's not a top suspect.
To start narrowing things down, I needed evidence. I began by opening a bottle from each batch I had on hand. A bottle from January 2018 was fine. A bottle from February gushed like crazy.  A bottle from a week or so later didn't.  Over the next two days, I opened at least one bottle from every batch I had made over the past year that I still had on hand. 

The result was depressing. Probably 65% of the batches showed clear signs of infection.  Some gushed beer 3-4 feet from the bottle. Others gushed only inches away.  In the end, at least 75% of the beer I had made in the past 14-16 months was infected and had to be tossed out.  About a dozen batches were fine. A few were overcarbonated but didn't appear to be infected.  I spent hours dumping entire batches of beer down the drain, rinsing the bottles clean, and removing the labels. 

It became clear that the brewing systems most likely weren't the culprit. I had at least one batch from each of them that wasn't infected, and batches from both that were. If the system was infected, I would expect all of its batches to be infected.  That left the fermenters and bottling wands.

As I got to some of the more-recent batches, a pattern began to emerge. There were four fermenters I used most-often in 2018 and 2019. They both featured a half-inch spigot. The other two featured a 3/8" spigot. Why was that important?  It meant that I used a different bottling wand with two of the fermenters than I used with the other two. It quickly became clear that batches bottled through the half-inch wand were all showing signs of infection, while batches bottled through the 3/8" wand were just fine.  I had my smoking gun. The half-inch wand was infected (and possibly the two fermenters, but I'd start with the wand).

I tossed both bottling wands and ordered new ones. That would hopefully clear the infection. I also made some adjustments to my procedures, in the hope that this will catch any future infections more quickly so that I never have to toss as much home brew again as I did this weekend.

From here on, my bottling procedure will change to:
  • Bottles should (continue to) get a hot tap water rinse until visually clean, then run through the dishwasher without any other dishes to minimize the risk of food particles causing infection. Bottles then need to be soaked in fresh Star San for further insurance. (This has been my process all along.)
  • Where possible, soak the bottling wand in boiling or near-boiling water to clean and sanitize it, then go a step further by soaking in Star San. In theory, this would eliminate an infection in the wand going forward. (This is a change. I used to use PBW to clean and Star San to sanitize, but that's clearly not good enough, at least not all the time.)
  • Caps will be soaked in Star San before use. (I've always done this.)
  • Stainless tongs will be sanitized and used to load the carbonation drops, to ensure that no bacteria from my hands enters the bottle. The tongs may be boiled or sanitized with the wand. (This is new.)
  • When a batch is bottled, record the fermenter used, bottling wand used, carbonation drop type, and where appropriate, the number of drops per bottle.  (I have not done this in the past.)
  • After any batch has been in the bottle for 30-90 days, open a bottle to check for over-carbonation and signs of gushing. If any signs are detected, check additional bottles.  (This is something I've also not done in the past, and it really "bit me" this time.)
  • If an infection is found check bottles from any other batches that went through the same wand and/or fermenter to ensure there are no gushers in there. Stop using that fermenter and/or wand until the infection is found and removed. (This should prevent me from having to dump a huge number of batches as I did this time, and result in only losing 1-3 before the infection is found.)
I noticed, too, that you can tell the difference between a bacterial infection and simple over-carbonation, at least in this case.  Overcarbonation resulted in a slow, gradual foaming of the beer up through the neck of the bottle and down the side. Maybe a third of the beer would foam out if you let it.  The infection caused a rapid expulsion of foamy beer through the neck of the bottle, and looked more like it was boiling out of the bottle than just foaming. 

Tonight I bottled a Belgian Dubbel from one of the four fermenters I use regularly. I made sure to hit the spigot with Star San before use, and to soak the new bottling wand and connecting tubing in Star San as well.  If this batch turns up infected, I'll know it's the fermenter... though this was one of the 3/8" spigots, so I'm inclined to think it will turn out fine.

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