Unidentified "off taste"

I've made lots of batches since I started. Maybe 30 or 40. I've never had any off flavors, so I'm not very good at identifying them. Certain ones I can immdeiately rule out, others I can't. 2 of my last 3 batches have had the same off flavorr. I'm not sure the other one didn't either because it was a strong stout. The only way I can describe it is either kind of like plastic (kind of like the keg tubing), or maybe even like iodophor. I can definitely say that it is not cidery, buttery, wet cardboard, astringent, green apple, grass, mold or any other typical ones. Fusels could be a possibility but I don't think so.
I do use iodophor, but I'm using it at the recommended dosage and in the exact same way. I've used glass and plastic fermenters, so I can rule that out. I've been using the same amount of yeast as I always do. Either a smack pack or a dried yeast like safale. I've never used a starter, but like I said, I've never had a problem. I have recently switched to AG, but have made numerous successful batches.
Only a couple things I can think of: 1. wild yeast from the grain. 2. recently I've been leaving my brew in primary for up to 4 weeks then going straight to the keg.
The taste is pretty subtle as well.

Are you racking you beer at really hot temps through hoses that aren't food safe or able to handle the heat? I'm not really seeing anything from what you wrote. I'd recommend you make a list of any changes you have made to your process over the last few batches and then rule each one of them out as the cause. This is a difficult thing to diagnose over the net.

Yeast autolysis may be a possibility from the flavor you've described. It's described as rubbery or like stale cheese, but I can see the plastic/iodine similarity. 4 weeks may be slightly longer than recommended in the fermentor depending on the temperature, trub composition, gravity, and health/volume of yeast pitched.

Have the past several beers been out of the ordinary in terms of gravity? Has the fermentation tempurature changed? How about your method for filtering break material from the kettle?

Has the switch to kegging been recent? When did you last clean the beer lines?

Do you also smell it right after opening the bottle? Maybe like a plastic-y smell and taste?

I had something like that in my first couple of batches which I think had something to do with overheating/burning the extract when I added it.

I've since started doing a late extract and watching my temp closer while boiling and it seems to have gone away.

Anyways, just a thought.

Try replacing your tubing, or buy a new autosiphon (if you use one). Sometimes it's the little things that carry the most influence.

methods are the same. Everything is the same: temp, procedure, sanitizer. My beer lines are clean. I did run some rum and punch through the kegs for a party, but I don't consider that a problem. The only way I filter hot break from the kettle is with my autosiphon. Switch to kegs has not been recent. Goin to have a pint in a minute and see if I can pinpoint the taste.

I was reading Papazian a few nights ago and read something I'd never heard before. I don't have the book in front of me, but it said something like: if you get too much flour (from the crush) in the mash, it can create off flavors. I've had the LHBS double crush my last few batches because I was getting poor efficency. Maybe this is the culprit?

Nope, now that I think about it, one of the "off" beers was an extract. Thought I'd keep this here though. Something to keep in mind. In the meantime, why does my beer taste like plastic?

This seems to be a recurring theme lately. I have a similar off flavor and I have not quite found the culprit yet but I think its yeast related. What yeast did you use and how did you pitch it (dry, temp, etc.)?

Pabst Blue Robot said:

Yeast autolysis may be a possibility from the flavor you've described. It's described as rubbery or like stale cheese, but I can see the plastic/iodine similarity. 4 weeks may be slightly longer than recommended in the fermentor depending on the temperature, trub composition, gravity, and health/volume of yeast pitched.

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Nah...Many of us leave our beers in primary for a month....Yeast autolysis requires several months on the yeast cake before it occurs (check the last paragraph in palmer.) 4 weeks is not enough time



BWRIGHT, can you give us more detail about the taste? Bandaid perhaps? Metallic? Twangy? Soapy?

Are you an extract or allgrain brewer?

What kind of water do you brew with? And what do you do to it before you use it?

Have you had other brewers taste these brews?

These two things are coming to mind...

METALLIC

CHARACTERISTICS: A harsh, metallic taste noted both on the tip of the tongue and the roof of the mouth. Can be felt throughout the tongue and mouth in large concentrations. Not desired in beer. Also described as tinny or bloodlike.

CHEMISTRY: The ferrous ion (iron) and some organic compounds formed by hydrolysis of cereal lipids in grain, and oxidization of free fatty acids.

HIGH RATE FROM PROCESS: Iron or mild steel in contact with beer; freshly-scrubbed stainless steel that has not been allowed to oxidize; improper filtering material; high iron content in water; poorly processed grain.

REDUCTION: Use of stainless steel; low-iron water; use of citric acid to re-oxidize stainless that has been abrasively cleaned; use of filtering materials that are acid-washed to remove iron; use of fresh, high-quality grain malt.

PHENOLIC

CHARACTERISTICS: A hospital-medicine chest flavor and aroma, best detected by its aroma components; caused by phenols. Some phenolic tastes are desired depending on the style. Other descriptions include Band-Aid-like, plasticlike, smoky, clovelike.

HIGH LEVELS DUE TO PROCESS: Yeast strain; chlorophenols in the water; improper rinse of chlorine sanitizers; oversparging; sparging above pH 6.0; sparging above 170 degrees; wild yeast contamination.

LOW LEVELS DUE TO PROCESS: Charcoal filtering of tap water; good healthy yeast strain; proper sparging while monitoring temperature and pH, good rinse of sanitizers or use of non-chlorine sanitizers.

EXAMPLES: Wheat beers have a high amount of the phenol 4-vinyl guaiacol that gives the characteristic clove taste.


I'm wondering if it's a build up of iirc chloramines in everything from the water you are using....

It is not twangy, or smoky. I'm pretty sure its not Band-Aid like. Although, that is kind of a plastic. Its not smoky or clovelike. Definitely not metallic. Its hard to say for me personally. I'm not used to "off flavors." I'm an AG brewer, but one of the batches that had the "taste" was an extract. That kit had some sort of Munton's dry yeast. The AG batch that had the "taste" I used Safale US-05 dry yeast. I pitch them straight into the wort. No rehydrating, but that's how I've always done it with no problems.
I use bottled spring water always. I don't do anything to the water, but I do use 5.2 in my mash. I have the LHBS crush my grains, and have been getting them double crushed. I do use about 180* sparge water, but I doubt that the grain bed is being raised to more than 165-170*. It's just plastic like.

I seem to have noticed quite a few here lately complaining of a similar off flavor (including myself) and every one I've seen/asked had used dry yeast, usually s-04 or us-05. My online research has led me to believe that its mostly ferment temp related but I also think my problem may have been caused by my method of re-hydration (too hot) because the one batch I pitched dry seems to be free of this off flavor (so far).

Links to similar issues:

Off Taste -- Fermentation temp & S-04? - Homebrewing - BeerAdvocate

Rubber Stopper Taste - Homebrewing - BeerAdvocate

Brews & Views Bulletin Board Service: Warm S04

Perpetual Homebrew Thread - Topic Powered by eve community

Do you think it could be the dried yeast? I've had this medicinal flavor both times I have used Safale Ale yeast. Both times I also used Iodophor but at recommended levels.
I have never had good luck with dried yeast, though the flavor cleared up after a month.
I went back to liquid, which has never let me down, and now use Star San for good measure.
I have read that dry yeast is always infected, but usually not at detectable levels, and shouldn't be repitched from a previous batch.

Almost alwyas use dry yeast. Never had a problem before.

BWRIGHT said:

Almost alwyas use dry yeast. Never had a problem before.

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What temp is your wort when you pitch the dry yeast? Also what are your fermenting temps?

Pitch at about 70. Fermentation between 68-70. Possible it could have got a little higher at some point.