I have been AG brewing for a year and a half and have never run into off flavors until recent. I have tasted a few bottles recently of two separate batches of two separate beers and am getting a similar aftertaste from both.
The sips are fine off the bat, decent body and malty goodness but after swallowing, I get this tonic water like bitterness. I hate tonic water!!! It coats the back of my throat and sides of my tongue and lingers for too long. I also get this slight artificial sweetness; the kind I get from splenda or sweet n low, though both were carbed with cane sugar.
Both are Belgian ales. One is a Dubbel style (Bottled in May), the other a Blonde (Bottled a month ago). The base grain is Pilsen with similar Belgian specialty malts. Both are lightly hopped I believe with Styrian and Kent Goldings, maybe Saaz.
I use a fly sparge method and I can't rule out that I over sparged or sparged with water that was too hot. My volumes recently have come up short, so I have been tipping my mash tun to get out all that I can. (I know, not good.) Also, I usually get my sparge water in the 190 range. My reasoning is that once the sparge water reaches this temp and my propane is shut off, it will dip down quite a bit in the time it takes to gently trickle over my grains. The grains, as a whole, probably aren't getting anywhere near the 180-190 mark. I know the described above, including my mash pH (which could be a tad high at 5.5) could cause astringent tastes. To me though, the taste doesn't seem astringent, rather a funky bitterness. Not the pleasant bitterness from hops.The beers seemed fine young once carbed. It seems whatever it is appears to be getting more pronounced over time. The bottles are not showing any signs of infection, nor am I getting excess carbonation. The taste is not plastic like either. I use high temp silicone hose for the transfer of hot sparge water and wort instead of vinyl hose. I treat my water with campden the night before brewing to drive off chlorine but don't really treat my water with anything else.
Any ideas on what the culprit of this taste could be? Thanks.