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Old 01-14-2010, 02:43 AM   #1
Gasman09
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Default Removing Metallic Flavors From Beer Using EDTA

My last batch of Bohemian lager had a distinctive metallic aftertaste which I traced back to a stainless steel scrub pad that I had placed at the base of the dip tube on my cornelius keg as a filter. The beer was fine until I racked it into the keg and added the filter... seemed like a good idea at the time. After about a day a very noticeable metallic aftertaste developed. I removed the stainless pad but the taste lingered.

EDTA is commonly used to chelate metallic flavors out of food products which can occur during processing. Specifically, Dow sells a product called Versene (I bought some plain old EDTA off of eBay, about $8 for 1lb). Large scale brewers may also use it as a foam stabilizer. It is added to many different food products as a color and flavor preservative. The Dow literature recommends 30 ppm concentration; it is safe in concentrations much, much higher.

Long story short, I added 500 mg to 19L of beer (about 1/4 teaspoon) and the metallic flavor disappeared instantly. Note: 1 ppm = 1 mg/kg. 19L = approx 19 kg. so 500 mg/19 kg = 26 ppm

Has anyone else tried this technique?


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Old 01-14-2010, 02:38 PM   #2
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First I've ever heard of it, but it sounds like a good emergency technique. Maybe you can add it to the wiki?


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Old 01-14-2010, 03:03 PM   #3
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Nice.

You can also add it to oxy clean and have something almost resembling a suitable detergent for brewing applications.
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Old 01-14-2010, 03:33 PM   #4
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I wish I knew that a few batches ago. Wish there was a product to remove the taste of "burnt mash." Coulda used that this summer
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Old 01-14-2010, 04:19 PM   #5
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http://www.chm.bris.ac.uk/motm/edta/...es%20of%20EDTA
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Old 01-14-2010, 04:47 PM   #6
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You have to be carefull with it in nucleic acid purifications as it will chelate many enzyme cofactors used in later modification steps (ie. binding of Mg required for DNA polymerase). Oops... sorry, wrong forum
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Old 01-14-2010, 06:39 PM   #7
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I think it does apply! That is apparently the mechanism for the preservative properties of EDTA... enzyme deactivation by chelating metallic co-factors. Not sure which beer bugs would be inhibited, though.
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Old 01-14-2010, 06:50 PM   #8
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Quote:
Originally Posted by Gasman09 View Post
I think it does apply! That is apparently the mechanism for the preservative properties of EDTA... enzyme deactivation by chelating metallic co-factors. Not sure which beer bugs would be inhibited, though.
Specifically, EDTA chelates the iron, limiting the amount of iron solution inhibits all but the most pernicious bacteria. No iron, no cytochromes, no metabolism.
It would also limit the production of variety of DNA repair enzymes that contain iron-sulfur clusters, p53 being a good example in ecoli.

Did you add the free acid or the sodium salt?
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Old 01-20-2010, 08:57 PM   #9
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Added the sodium salt.
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Old 01-20-2010, 09:52 PM   #10
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Quote:
Originally Posted by Rushis View Post
Specifically, EDTA chelates the iron, limiting the amount of iron solution inhibits all but the most pernicious bacteria. No iron, no cytochromes, no metabolism.
It would also limit the production of variety of DNA repair enzymes that contain iron-sulfur clusters, p53 being a good example in ecoli.

Did you add the free acid or the sodium salt?
we use it to stop DNA or RNA polymerase reactions, as well as a preservative for plasmid DNA preps. EDTA will chelate Mg2+ which is required as a catalyst to bend the template DNA in to the proper configuration so the polymerase can bind and copy the template. At least thats what I remember from Bio-chem ten years ago.


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