An off-flavor that doesn't fit the usual description

Howdy--

New here to the forums as a poster, but have found so much great info so far, so thanks all! Brewed an attempt at the coriander/orange peel varietal, and encountered a flavor that I'm pretty sure shouldn't be there but don't know why it is. Basically it tastes like the syrupy sweetness of cream soda with a dose of plastic. I hesitate to call it the "band-aid" flavor because there's no sharpness to the flavor, rather it is more on the vanilla side. Anyone have ideas? It's not ruined, but the flavor doesn't belong. Rough recipe is LME, 1lb Special B Malt/ .5lb Munich (158 steep for 30), 2 charges of EKent Goldings, coriander, and bitter orange peel. Fermented 3 weeks at 68 degrees, racked to a corny keg, and it has been carbonating at 14psi for 5 days now (38 degrees.) Do my best to clean, wash first then ez clean no-rinse right before use of equipment.

Thanks!

How about water? Did you use no chlorinated water?

The plasticy flavor is almost certainly going to be chlorophenols. You might want to try adding a campden tablet to your next batch of brew water to see if that clears it up.

The other part of the flavor is probably just a mix of green beer flavor with the biscuity maltiness of the munich malt and a hint of the bitter orange peel. I haven't seen many recipes that use exclusively bitter orange peel, it's usually either replaced with sweet orange peel or mixed with sweet orange peel. (I've seen it written that bitter orange peel can leave a metallic off taste behind, but I haven't experienced that personally.)

Quick responses and thanks!
I hadn't even thought of the water--fwiw, I use tap water in a 3 gallon boil, and then I top off w/water from the Culligan machine at Meijer (grocery store.) Tap water doesn't taste bad to me, but I smoke and brewing usually involves bourbon, so my taste buds might not be at their finest...

Thanks for the heads up on the orange peel mix--this is my third time with this recipe--it's tasted great every time, and usually gets better with age. The goal here was to slow carbonate in the corny outside, then drop it in the wine cellar (55-60 degrees) for several months.

If it hasn't happened before, then there's a good chance that for one reason or another the water company had just added a bit of extra Chloramine to your water. The next batch will probably be fine.

That said, for extract it's completely fine to use nothing but distilled or RO purified water, since the extract already includes the water minerals from the original grain extraction. I think that Culligan adds some flavor enhancing minerals to their water, but not enough to throw anything off.