[WWBF]

I made a batch of red ale a while back and it has an off taste of plastic. What could be the cause? Water? I used bottled water to brew but i used tap water to sterilize everything while brewing.   

[denny]

It could be the tap water, but I think that's pretty unlikely.  Maybe an infection.

[mchrispen]

Without more detail about the recipe and brewing process, we are shooting in the dark a bit.


For me, most of the plastic/medicinal tastes come from chlorophenols, which is the result of not properly handling the source water for your brew. This is true of both all grain and extract brews. The use of campden tablets or metabisulfites to remove both chlorine and chloramines from your water source should eliminate the issue. Chlorine is readily handled by filtration through an active charcoal filter, but watch the speed of filtration. Chloramines tend to break through filtration as they are much more stable, but can be consumed by active charcoal or charcoal block filters if the contact time is adequate. Campden is cheap and easy.


Another possibility is yeast health. Dramatic underpitching of yeast, stressors such as not tempering the yeast to the wort fermentation temperature, lack of temperature controls (fermenting too hot), lack of oxygen, can all promote phenolic off flavors. I have gotten big phenols from yeast that I stored improperly, despite making a starter. I suspect contamination in that batch of yeast.


Bottled water should not have chlorine, and it seems unlikely that the residual water from sterilization would cause a strong plastic off flavor. Did you use anything specifically that would add a strong plastic flavor?

[JJeffers09]

+1 for your tap water

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[Stevie]

It could be the tap water, but I think that's pretty unlikely.  Maybe an infection.

Why unlikely? I'd say that's the first variable to check. Add some campden to the tap water before adding your sanitizer

[denny]

It could be the tap water, but I think that's pretty unlikely.  Maybe an infection.

Why unlikely? I'd say that's the first variable to check. Add some campden to the tap water before adding your sanitizer

I can't imagine there's enough water left to taste the chlorine.

[Stevie]

From what I remember, the taste threshold is crazy low.

I'm sure Bryan or Martin will know, but looking around it it's less than one ppb in water.

[denny]

From what I remember, the taste threshold is crazy low.

I'm sure Bryan or Martin will know, but looking around it it's less than one ppb in water.

Seems like you'd also have to take into account the amount of water left in the equipment.  If there's a total of 1/4 tsp. of water left, spread over all the surfaces, is that enough?

[brewinhard]

I made a batch of red ale a while back and it has an off taste of plastic. What could be the cause? Water? I used bottled water to brew but i used tap water to sterilize everything while brewing.

What did you add to your tap water to make your sanitizer? 

Plasticy notes can also be a sign of a wild yeast infection. Is it more light plastic, or bandaid like?

[Westley]

I made a batch of red ale a while back and it has an off taste of plastic. What could be the cause? Water? I used bottled water to brew but i used tap water to sterilize everything while brewing.

I recently got a case of bottled water from the store (to drink, not to brew with), and all of the water had a plastic taste to it. I wonder if maybe you ran into a similar situation.

[bboy9000]

Could be dirty bottles or kegs.  I tasted medicinal phenols a friends beer.  I assumed it was a water problem (chlorine) or a sanitization issue.  Turns out it was a cleaning issue.  I noticed a light film on the bottles only visible when held to light.  The bottles looked clean but weren't.  A hot pbw soak followed by sanitizer solved the problem.

[santoch]

it could be a wild yeast contamination.