Tag Archives: phenol

Dealing with an Off-Flavor

Please note: I have since discovered the problem seems to be something completely different. While chlorine in brewing is definitely a problem, this whole post should be taken with a grain of salt.

I’ve now had four batches ruined by a nasty, smoky plastic off-flavor that is first noticeable shortly after fermentation begins. This is commonly attributed to chlorine in the water, something I have always treated. Tracking down the cause has thus been difficult, especially since there is pretty much nothing I did or used brewing these that I didn’t elsewhere without problems:

  1. Pale ale, 5 gallons, March 2012
    • Hagerstown, MD tap water w/ 1/2 Campden tablet in 10 gallons
    • Rahr 2-row, English crystal 60L, wheat malt
  2. Chicha de jora, 2 gallons, May 2013
    • Washington, DC tap through PB-1 carbon filter (~6 months old)
    • Peruvian maiz jora (malted purple corn)
  3. Pale ale (different from #1), 1 gallon, July 2013
    • Washington, DC tap with 1/4 Campden tablet in 5 gallons
    • Briess 2-row, Briess crystal 20L
  4. Chicha (different from #2), 1 gallon, October 2013
    • Washington, DC tap through Watts carbon filter (~2 months old) and treated with a full Campden tablet in 5 gallons
    • Briess 2-row, maiz jora

I didn’t slouch, as far as I can tell, in removing chloramine from the water. I made many batches using carbon-filtered water without further treatment, and made two good beers using raw tap water with Campden for dechlorination. Batches 2-4 didn’t make it to bottling, but #1 did and I used Brita water to make the sugar solution. Up until #3 I also did not treat the water used to make the sanitizer, either StarSan or iodophor. With #4 I used distilled water to mix the StarSan. Since this still didn’t solve it, I was about ready to give up on water as a factor.

I’ve considered a few other potential contributing factors. I was able to eliminate contamination as a possibility through saving unfermented wort, sterilizing it and carefully pitching yeast on two of these batches. Both times I got the off-flavor, even using other yeast strains. I thought also about oxidation, either in the mash or in the grains themselves since some of these were pre-crushed and a little old. But that theory fell apart with batch #3, which used malt I bought that day and crushed 30 minutes before mash-in. Plus, as far as I can tell the plastic flavor points in the direction of phenols, not oxidation. Cleaning products and such were also fine as far as I could tell, and saving the wort as mentioned above also helped eliminate some of those variables. As for equipment, batch #1 shared only a copper immersion chiller with the other three, as I wasn’t brewing at home.

I was at just about my wit’s end with this when I got a new bit of info. Reading AJ DeLange’s HBD article about dechlorination, I found out that chlorophenols can form in the water supply itself. Phenols are abundant in nature, and can react with chlorine at the water treatment plant just as it would in your beer. In that case, dechlorinating the water doesn’t do any good since the chlorophenols are already formed–assuming, of course, that I understood the article correctly.

In retrospect, for at least batches #3 and #4, the water had a bit of an earthy taste. I’ve noticed that a lot here after rainstorms. Even through the filter the taste was there. I don’t remember what the water for #1 or #2 tasted like, so I can’t say for sure this is related to the problem (not that I could if I did, anyway). But, at least, it’s something to go on.

I have to do a lot more testing, but it could be an issue of bad upstream water quality, and in the case of filters I could have run the water too quickly. With too high a flow rate the water may not be spending enough time in contact with the carbon. AJ and many other brewers are unequivocal about carbon filters’ efficacy in removing chloramine, despite some claims to the contrary, but the rate is definitely a factor. The removal of other undesirable compounds is also affected. So, it sounds like the way to go for me is slow filtration, and perhaps getting a chlorine test kit to verify effectiveness.

I made another batch this weekend, a light cream ale in which any such off flavor will be obvious. I ran water through the filter very slowly. It was clean and had no off taste or smell. The 2-row malt was the same as in #3 and #4. To sample without disturbing the main batch, I separately fermented sterilized leftover wort as I’ve done before, and so far it is clean. I’m just hoping that holds true.