Chlorine, chlorophenols and the boil phase

Discussion in 'General Brewing Discussions' started by AC, Feb 16, 2018.

  1. AC

    AC New Member

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    The water where I live and brew is lightly chlorinated by the water authority - free chlorine but no chloramine; you can just taste it occasionally in a glass of water or smell it in the steam from a hot shower. I have always removed the free chlorine prior to brewing by either gassing off my brewing water over 24 hours prior to brewing or boiling for 15 minutes.

    I have always done this as I have read in many places on the internet that chlorine in brew water (even if not able to be tasted directly) can potentially generate unwanted chlorophenols during the fermentation phase of the brew. Removing chlorine in this way therefore ensures the removal of one potential source of off flavours from the finished beer.

    But here is my question: if chlorophenols from chlorine in the brew water are only created in the fermentation phase through interaction of chlorine with yeast and fermentation byproducts and if boiling removes free chlorine in water, then would not the standard boil phase (60-90 minutes) in the brew process always remove free chlorine from wort prior to it getting into the fermenter?

    If so, how can chlorophenols be created from chlorine in the brewing water? They may obviously be generated from other interactions, but if there is no chlorine, which ones and how?

    I do not want to challenge any orthodoxy regarding chlorine and chlorophenols and, no matter what the answer to my question, I will still remove the chlorine from my brew water prior to use (it smells and tastes nicer), but have I missed something about chlorine, chlorophenols and boiling wort?
     
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  2. Trialben

    Trialben Well-Known Member

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    it sure sounds reasonable. i just filter my tap water im told by the water guy at markets that this double filter removes chlorine from my water my taste buds backs it up.
     
  3. vthokiedsp

    vthokiedsp Member

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    I'm not a water chemistry expert by any means. Usually, I do the bare minimum water adjustments. But, I'm gonna make an educated guess based on my engineering experience in the water/wastewater industry. Like with a lot of ions and nutrients, there are different forms, bonds and types. Boiling and offgassing may take care of certain types of Cl but other types may be persistent unless chemically forced to precipitate out of a substrate. Maybe those persistent ions make their way through the process and a reaction during fermentation utilizes those ions to contribute to the presence of a chlorophenol. Just a guess like I said. I'd be interested to see what others have to say as well. I've had a couple of beers have a vinyl aroma and taste despite using potassium metabisulfite and have wondered if my dosing was too small or if there is another form of chlorine making it's way through.
     
  4. Nosybear

    Nosybear Well-Known Member

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    The chlorine/phenol reaction occurs when phenols, present in every wort, meets chlorine. The reaction happens in the mash tun, in the boil and yes, during fermentation. The flavor threshold for chlorophenols is insanely low - parts per trillion, if memory serves. If you clean your equipment with a bleach solution and don't rinse enough, chlorophenols. The classic band-aid flavor is really only noticeable at high concentrations. At lower concentrations you'll get a harsh, chemical bitterness. When advising beginners, chlorine removal is the one water treatment I recommend. It's that nasty.

    And it's easy to remove. It takes about 0.2 grams of sodium metabisulfite to dechlorinate ten gallons of tap water, yielding a tiny amount of sodium, chloride and sulfate in your water. A Campden tablet will dechlorinate 20 gallons of water. Overdosing won't hurt a thing: If you don't feel comfortable working with that small of a weight, just grind one up and throw it in. There's no reason to have chlorophenols in your beer, it's too easy to get rid of the chlorine.

    I've arrived at this by trial and error. There was always a harshness in my beer I couldn't get rid of, no matter how I changed the malt bill, the hops, a vague, chemically bitterness that would not go away. I had been using an RV filter - activated charcoal - thinking I was removing the chlorine. Once I started dechlorinating with Campden tablets, the flavor went away. You're lucky, you have free chlorine. That will boil off (but do boil it off before starting the mash!). We have chloramine, which won't boil off. Dechlorinate and your beer will improve, in fact, it's the one water treatment that makes an immediately noticeable difference in your beer.
     
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  5. Hawkbox

    Hawkbox Well-Known Member

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    I generally just break one in half and cruch each half in a 5 gallon bucket. But I only recently started doing it as I misread the water report and didn't realize my municipality uses chloramine.
     
  6. Nosybear

    Nosybear Well-Known Member

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    As good an approach as any!
     
  7. AC

    AC New Member

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    Thanks Nosybear for the information - this clarifies things for me. I did not know that the chlorine/phenol reaction could occur in all phases of brewing, not just fermentation. I have read about Campden tablets and may start using them as a guarantee to knock out all chlorine. I was reading some more from my water provider's website today and they now mention additional use of chloramine for disinfection "when required". In other words, I will never know when.
     
  8. Hawkbox

    Hawkbox Well-Known Member

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    I did the same thing. I misread a water report and then a buddy of mine that brews showed me where the actual mention was.
     

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