Off-flavor tasting course

CO-Brew, located on Broadway in the Golden Triangle District in Denver, was hosting an off-flavor tasting course.

We got a control PBR and got to taste our way through several common off flavors.

  • Acetaldehyde
  • Skunk/light-struck
  • DMS
  • Diacetyl
  • Phenols
  • Metallic
  • Sour
  • Butyric acid
  • Oxidized
  • Sulfurs
  • Caprylic/cheesy

It was pretty gross, but educational. I’d read a bit about these flavors before, so it was good to try them out.  Despite feeling better about my ability to identify them, I failed the test at the end, whaa-whaa.

I did get to ask the main dude at the shop running the course if I could ever bring in beers that were off and ask for help, and he said absolutely.  I started to describe the problems with my first two beers (Porter: Seasonal Limited and Cinnamon Toast Cream Ale).  Holly and I had gone back and forth on what was wrong with these beers.  I knew at this point that I’d over hopped them, and phenols seemed close to what was wrong, but the sample we tasted in the class was 100% clove/bandaid, not really the rubber glove I was getting in these two beers.  Plus, I’d read that phenols were usually from leaving some chlorine in your gear, or getting an infection and I knew neither of those were my problem.

As soon as I said the phrase “rubber glove”, the brewmaster asked me what temperature my fermentation space was.  Without skipping a beat, I said, “yep.  Yeah.  Yes.  This is my problem.”

I don’t know why I hadn’t thought of it before.  My saison yeast beer came out great.  Belle Saison likes to be fermented “above 68” according to the manufacturer, and while no upper limit is described, it’s assumed that it can get in the mid 80s before anything weird happens. Meanwhile, my two beers fermented with an english yeast strain (which prefers being 58-68 degrees) came out terrible.

I explained this to the brewmaster, and he told me, yeah, a lot of people in that situation would just brew Belgians in summer.  I realized that my first batch was a wheat beer, which is another yeast strain that is comfortable fermenting warm.

This all made sense and was such a forehead-slap lightbulb moment.  I needed to come up with a way to control temperature in my fermentation space, and needed to pitch lower.


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