Baltibrew Yeast Capture: Kickoff!

Baltibrew members hail from a wide range of professional backgrounds, from the service sector to the arts to engineering and finance.  Among our ranks are several bonafide microbiologists.  Drawing on their expertese, the club has embarked on a challenging and multi-part project for the year: we're going to try to capture, isolate, culture, and evaluate a Baltimore native brewers yeast!

Finished capture kit for club members.

While a number of our brewers produce tasty beverages via spontaneous and mixed fermentation, there are a several challenges in an attempt to isolate a strain of yeast for brewing purposes.

  1. Capturing anything interesting at all!
    Leaving our capture media outside doesn't guarantee we'll end up catching something that will ferment instead of just spoil.  We'll be casting as large as net as we can in the hopes of finding candidate organisms.
  1. Capturing something that will ferment strongly on its own.
    In a mixed fermentation, the processing of various sugars into ethanol and other compounds is a team game.  We're looking to isolate a strain of yeast that can do the job itself and there's no assurances that the yeasts we might capture will be able to tackle the simple and more complex sugars found in wort.  After we've selected candidates from our captures, we'll need to test them to see if they are up to the job.
  1. Capturing something that is not the Chico strain.
    We're brewers and we're surrounded by brewing yeast!  It's in our homebrew.  It's likely floating around our houses.  We'll need to take care that we don't end up "capturing" an organism that we've brought into our local environment.
  1. Capturing something that makes a pleasing beer.
    And here's the big question.  Even if we capture and isolate a yeast or yeasts that are up for the job, there's no way of telling if they'll make a pleasing product.  After all, brewers yeasts has been living with humans for a very, very long time and have been heavily subjected to selection pressure.  People have been knowingly (and unknowingly) changing the organism by reusing pleasing results, selecting for attenuation, floculattion, expediency, and taste.  If we are successful in wrangling a pure strain of yeast that will ferment a wort of malted barley, are we lucky enough that it should make a tasty brew?

After discussing the challenges, we set about designing a simple protocol and capture media to distribute to club members at our April meeting, with the intention of collecting promising candidates at the next.  We prepared and processed the capture media into 8 oz mason jars. Starting with 1 liter of distilled water and 143 grams of DME, we calibrated a pH meter and added enough lactic acid (~.5 mL) to drop the solution below 4.50 pH. The wort ended up at 1.025 SG (as converted from a Brix reading of 6.4) and a pH of 4.38. We processed 20 jars filled with 100mL of the media and half of a hop pellet each in a pressure canner at 15 PSI for 15 minutes.

Pressure canner heating up.

While the canner ran, we crafted airlocks from extra mason jar lids, rubber grommets, and S-type airlocks.  The goal here was to provide a members with a simple way to limit oxygen exposure after capture, hopefully keeping some of the less favorable aerobic organisms in check.

Airlock lid for after capture.

The capture media, modified lid and airlock, clean cheesecloth, and a protocol sheet were bundled into a capture kit for members to take home.  Members may choose how to conduct their capture; either directly from a biologic sample like a flower or fruit, or from the outside air itself.  Admittedly, the odds are low but the fun is be in the attempt.  Read more as we take our captures into the lab!

Sterile capture media.