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.

6 thoughts on “Dealing with an Off-Flavor

  1. eurekabrewing

    I hope you get rid of your off-flavor soon. Man am I lucky to have really good ground water available after reading what you went through. All the best

    1. DC Yeast Lab Post author

      Thanks, Sam. The water here is actually not that bad, especially through a filter. I know a lot of homebrewers (like the Mad Fermenationist) and a few pro breweries here are using it. The odd part is I’ve heard of people who use filters and people who use Campden and never anything like what I’ve experienced lately. So far the latest batch seems to be good, but I’m not close to bottling it yet.

      By ground water do you mean you have a private well, or is your city’s water authority getting it from a well?

      1. eurekabrewing

        The city gets the water from a well which is ground water from a nearby river. My hometown was once known as the Munich of Switzerland because we had several resitent breweries. One of them was one of the first using steam power for production and shipped beer as far as Paris. The water we have here is perfect for brewing.

  2. Sui Generis

    You may have mis-read the article (or given us the wrong link) – the article is on chloramines, which are not the same as chlorophenols (although they are related).

    Both chlorophenols an chloramines form when chlorine reacts with living matter (as both amines and phenols are common in life), so your proposed issue is well within the realm of reason – chlorophenols and chloramines would occur if you were getting a lot of organic matter into your water supply. Chloramines are also added as a sanitizing agent in some water supplies. If you have chloramines only you won’t taste it in the water (the taste threshold is quite high), but the opposite is true of chlorophenols. If they are present you will taste them in your tap water. If you don’t taste them in your water, they are unlikely to be in your water.

    Chloramines are relatively flavourless, but will form chlorophenols in wort – carbon filtering &/or campden tablets will get rid of them. Chlorophenols can be removed by carbon filtering, but are generally harder to remove using this method than chloramines.


    1. DC Yeast Lab Post author

      Hey, Bryan. I am definitely confused about what’s at work here, although I can confirm DC Water uses chloramine for the greater part of the year, switching to plain chlorine for about a month every year. The water I used on the first batch with the issue (in Maryland) also uses chloramine and comes from the same source as DC’s, the Potomac River.

      The part of the article I was referencing was on page 5, the first paragraph: “They can be produced at the water treatment plant as well and the author has seen puzzled queries as to why beers made with thoroughly dechlorinated water still present chlorphenolic flavors. The answer is that the chlorphenols were already there!” I notice sometimes when I drink plain tap (without the filter) I get a weird plasticky burp, for lack of a better description. The same is true when I drink one of the affected beers. Right now that’s about all I have to go on, since I’ve never distinctly tasted any plastic notes in fresh tap water.

      I get a big chlorine aroma with a glass of plain tap water. If I treat that same water with metabisulfite or thiosulfate, it goes away. With water through the filter, I don’t notice an aroma at all. Right now, it’s definitely chloramine according to the water authority. What’s truly weird is this only happened a year and a half after starting to brew (except for #1) despite using the same kinds of filters for that whole time. I actually the filter casing specifically for brewing and it and the cartridges didn’t fail me until this May. I actually tried raw tap with Campden due to that failed batch.

      So yeah, it’s a mess whose factors I can’t quite link together in any seriously meaningful way.

  3. Pingback: Off-flavor Follow-up | DC Yeast Lab

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