Day 158

Sam Corbeil brought some beer to Microbiology Lab today. Not the kind you would want to drink (unfortunately), but the kind that had been left in a forgotten cask at room temperature for several weeks: a funky-smelling evil-looking cloudy orange liquid with a thick sludge at the bottom. This gave us an opportunity to try to ID the little critters that had turned it to the Dark Side.

Using a miscroscope

Hunting for critters--baseball hat optional

First we took a sample from the very vinegary, cidery smelling liquid and prepared a microscope slide. Looking at the invaders at 400x magnification, we could see both rod-shaped and cocci (round) bacteria.

Next we stained another slide with ammonium oxalate, Gram’s Iodine solution and Safranin-O. Any bacteria that appeared blue or violet under the microscope were “Gram-positive”, any that turned red or pink were “Gram-negative”. In this case, they were all Gram-negative.

Finally we dropped some hydrogen peroxide onto them to detemine if the bacteria were catalase-positive (bubbles form) or catalase-negative (no bubbles.) Our sample was catalase-negative.

With all the evidence at our disposal, we narrowed the field down to either an acetic acid bacteria or some form of acetomonas.

In Packaging, we continued our examination of draught systems by taking apart a keg and then taking apart the keg’s spike–the long metal tube in the keg that sucks up beer.

We also looked at other pieces of the draught system, including multi-keg dispensing tubes, couplers, and the F.O.B. (Foam on Beer), a useful device that detects when your keg has run out of beer and is dispensing nothing but foam.

Then we went on a field trip–all the way to the campus beer store, where we examined the store’s draught system set-up. And while we were in the store, it seemed like a good idea to sample the beer on tap. Best. Field Trip. Ever.

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