This is a continuation of this thread I started:
After doing more testing, I can conclude this is not a fermentation issue.
I have done a test batch with three different yeast strains (in brand new 2 gallon buckets), with appropriate pitching rates and 60 seconds of pure o2 from a diffusion stone.
Each test batch was just sampled and it had the same honey-like or caramel flavor as the body of the beer and a sweetness that people classify almost as buttery. But again, this flavor is not unpleasant, many of my friends really like it, but it is not as I intended it. This sounds just like pentaindione, which is a yeast bi-product. However, I tried using biomat dar which is inhibits the precursor of diacetyl and pentaindione from happening.
Any ale I make (mostly with light body) are dominated by this flavor. Even lagers have this similar off taste to some extent. In fact, I had a light lager that I forgot about because it had this flavor sitting in the fridge and out in the basement on and off for probably 8 months, this very beer now tastes amazing and has no sign of the off flavor.
So back to what we know:
We know its not a fermentation issue based on the temperature being in the mid 60s and holding constant, pitching enough yeast and getting proper o2 as well as testing three different yeast strains (US-05, WLP029, WLP090). Fermentation was conducted in brand new buckets that were given a good oxi soak and sanitized.
I also tried a lighter boil to see if kettle caramelization was an issue since I have a very vigorous boil, but the last batch still had this off flavor with a lighter boil.
With 10 minutes left I also circulate the boiling wort into pumps and the CFC so they are sanitized. A few batches ago I also gave it a good hot PBW soak and circulated it throughout the entire system of kettles and also used Acid 5 to give it an acid rinse. Again, anything in the BK should be safe anyways since it gets boiled.
The one final tid bit that has me thinking is this: When I started brewing extract 3 years ago, I recall this same taste and I have just now identified this. The only thing my extract days have in common with now was US-05 yeast, and the same city water, which by the way is excellent:
Ca - 20.5
Mg - 13.1
Na - 13.2
K - 0
Iron ~ 0
Bicarbonate - 85.9
Carbonate - .7
Sulfate - 21.1
Chloride - 33.4
Nitrate - .3
Nitrite - 0
Fluoride - .6
The water tastes great and to me is just as good as bottle water. However, at this point it's one of the only variables left to try to change. The only other suggestion was to try a different base malt. I currently use Briess 2-row.
Finally, I made a dry stout which came out great to me. However, it had black barley in it and it may be just 'hiding' this taste.
At this point the only thing I can think of is to try RO water and just see what the results are. I have gone to my LHBS store as well as talked to club members and we are somewhat stumped.
I have a hard time thinking its a bacteria infection since we have tried new fermenters and everything is getting cleaned and sanitized before touching the wort. If its not a fermentation issue, what's left?