Author Topic: US-05 giving a medicinal flavor  (Read 257 times)

Offline Kirk

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US-05 giving a medicinal flavor
« on: April 25, 2019, 12:12:23 PM »
I don't typically use US-05, but I did in this last American Amber. I noticed a slight medicinal or alcoholic flavor about the middle of fermentation, which I attributed to a "green" beer. In the past I've gotten a fair amount of green apple from this strain during early fermentation.

I allowed the beer to sit in the primary for about 11 days total, with the gravity remaining at terminal for around 5 days. I've been cold crashing it for about 3 days now. I took a sample of it this morning, and I'm still getting the medicinal taste. I don't have that much experience with this yeast, but I wasn't expecting this.

Temperature was between 67 to 72 max (I intentionally raised the temp for a Diacetyl rest after 3 days at terminal gravity).

Thoughts? I have 2 other beers going right now as well, and they all had a little bit of this. I'm wondering if it's my pallet this morning? WLP029 (German Ale/Kolsch) and WLP820 (oktoberfest).

Offline BrewBama

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US-05 giving a medicinal flavor
« Reply #1 on: April 25, 2019, 12:53:17 PM »
I don’t have a lot of experience in this area but I’ve read that medicinal flavors can be caused by wild yeasts contaminations,  chlorophenol presence in tap water, and chlorine sanitizers.

Where do you source your water? How do you pretreat your water? How do you sanitize?

Has the municipality changed the water composition for the upcoming warmer weather?  I believe I read Martin say that water authorities will “super flush” the system if they get a micro flora bloom and with the impending warmer weather it seems timing would be right and coincidental that the problem surfaced now.

Iodophor will kill wild yeast if that’s the problem. If you have a spigot in the fermenter disassemble and closely inspect, clean and sanitize it.

Of course, I may be full of beans...


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« Last Edit: April 25, 2019, 12:59:42 PM by BrewBama »
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Offline Kirk

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Re: US-05 giving a medicinal flavor
« Reply #2 on: April 25, 2019, 01:13:48 PM »
I don’t have a lot of experience in this area but I’ve read that medicinal flavors can be caused by wild yeasts contaminations,  chlorophenol presence in tap water, and chlorine sanitizers.

Where do you source your water? How do you pretreat your water? How do you sanitize?

Has the municipality changed the water composition for the upcoming warmer weather?  I believe I read Martin say that water authorities will “super flush” the system if they get a micro flora bloom and with the impending warmer weather it seems timing would be right and coincidental that the problem surfaced now.

Iodophor will kill wild yeast if that’s the problem. If you have a spigot in the fermenter disassemble and closely inspect, clean and sanitize it.

Of course, I may be full of beans...


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Thanks for the response. I haven't tested my water in a while, but I do run it through active carbon (very slowly) to help with the chlorine issue. I'm usually very good about sanitation and use PBW and Starsan for cleaning/sanitizing. I'm using a bucket with no spigot, and typically run the boiling wort through the counterflow exchanger for the last 15 mins of the boil.

I'm pretty meticulous regarding cleaning/sanitizing, but who knows.

I'm starting to wonder if it was a temp problem. I use an inkbird temp controller with a heat wrap to control the temp. I've noticed that it sometimes doesn't respond to the temp and keeps applying heat even though the temperature is too high. I do remember the temperature spiking a little bit. I've ruined a couple batches with this controller and wondering if I should just ditch it altogether.
« Last Edit: April 25, 2019, 01:42:42 PM by Kirk »

Offline RC

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Re: US-05 giving a medicinal flavor
« Reply #3 on: April 25, 2019, 03:20:23 PM »
Medicinal flavor is chlorophenol. Two possible sources are your brewing water and wild yeast infection. It's not an off-flavor caused by high fermentation temp.

You can get chlorine test strips to see if your brewing water has anything left in it after filtering. If so, and if your city uses chlorine, it shouldn't matter because the chlorine will gas off when the water is heated. If chloramine is used, try using campden tablets.

Wild yeasts are very tolerant of low pH and so aren't killed by acid-based sanitizers like star-san or saniclean. Try switching to iodophor as your sanitizer--I recommend this regardless of the source of your off-flavor.

Offline Robert

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Re: US-05 giving a medicinal flavor
« Reply #4 on: April 25, 2019, 03:24:44 PM »
Medicinal flavor is chlorophenol. Two possible sources are your brewing water and wild yeast infection. It's not an off-flavor caused by high fermentation temp.

You can get chlorine test strips to see if your brewing water has anything left in it after filtering. If so, and if your city uses chlorine, it shouldn't matter because the chlorine will gas off when the water is heated. If chloramine is used, try using campden tablets.

Wild yeasts are very tolerant of low pH and so aren't killed by acid-based sanitizers like star-san or saniclean. Try switching to iodophor as your sanitizer--I recommend this regardless of the source of your off-flavor.
^^^^All this.
Rob Stein
Akron, Ohio

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Offline Bob357

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Re: US-05 giving a medicinal flavor
« Reply #5 on: April 25, 2019, 03:36:13 PM »
Never would have known this, but a friend had chased a medicinal flavor for several months. He finally found it was caused by algae growing in a short length of clear tubing between his sediment filter and HLT.
Beer is my bucket list,

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Fallon, NV

Offline BrewBama

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Re: US-05 giving a medicinal flavor
« Reply #6 on: April 25, 2019, 11:27:40 PM »
This is the subject of an article on AHA as well: https://www.homebrewersassociation.org/how-to-brew/off-flavor-series-chlorophenol/


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“From man’s sweat and God’s love, beer came into the world.” — St. Arnold

Brewed in the Tennessee Valley. Rocket City — Huntsville AL