Accidental Cross Contamination

Cleaning and sanitation are critical to brewing success.  I recently had a cross contamination from my sour beers to my clean beers.  I brewed my Christmas Ale (Sleigh Ride) on September 26, 2015.  On October 17th, I racked it to secondary, as I wanted to use the yeast on my October 18th brew (a chocolate butternut porter).  I had made a larger batch of the sleigh ride, so that I had 5.5 gallons at bottling.  Which meant that my 5 gallon carboy secondary would be to the rim.  I had a one gallon fermenter that I put the remaining 1/2 gallon of Sleigh Ride into.

I had rinsed my racking hoses and auto-syphon in chlorine water (2.5 tablespoons to 5 gallons).  I only left them in the chlorine water for about 5 minutes, then rinsed them really well with water until the chlorine smell was gone.  I then heavily rinsed them in Star San solution before using them.  Well, as you can guess, I still had some leftover surviving microbes from the blending of my sour beers back in July!

What is really interesting is that the 5 gallon carboy (which is filled nearly to the airlock) does not show any signs of contamination, while the half full 1 gallon carboy has a full on pellicle going on!  The “Accidental Sour Beer”.  Here are photos of the two carboys.

IMG_1148No pellicle in the 5 gallon carboy!

IMG_1146Full on pellicle in the half full 1 gallon carboy.  When I make sour beers, I usually have something in mind.  Since this wasn’t preplanned out it could be really good or really bad!

I’ve done a lot of reading since I noticed this pellicle.  I’ve read up on what causes a pellicle to form.  I have done some reading on cleaning, sanitizing and sterilization.  The take aways from that reading are:

  • 5 minutes in a chlorine solution probably isn’t enough!  30 minutes minimum.
  • Plastics can acquire the chlorine odor and transfer to your beer.  I used chlorine exclusively from 1991 to 2012 and never noticed a chlorine odor in my beer though.
  • Chlorine will pit stainless, so it’s use on stainless isn’t advised.
  • Keeping separate plastic equipment for sours only is a great idea.  Also, don’t let your clean beer plastics touch your sour beer.
  • Oxygen probably made the difference in this batch.  The microbe that I suspect led to this pellicle is Lactobacillus Brevis.  The 1/2 gallon of head space in the 1 gallon fermenter gave the Lactobacillus Brevis enough oxygen to start working on the complex sugars and thrive.
  • Purchase new plastics for my clean beers.
  • Take all my old plastics, clean them really well, and mark them and use them on sour beers only.  Also, store them separately from my clean beer plastics.
  • It might be prudent to take the 5 gallons that isn’t souring and bring it up to 160 degrees F in my boil pot to pasteurize it, then add new yeast at bottling time.  I’m really leaning towards this, to avoid bottle bombs!

We’ll see how things progress from here.  The souring Christmas Ale might end up being a great beer, but it definitely won’t be ready for Christmas 2015.  Maybe it will be ready for next Christmas!



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