What am I tasting?

[coolharry]

So a while back I brewed a cream ale to try and coax my relatives over to real beer. It was my first attempt at a light adjunct loaded beer. Recipe:
70% 6row
20% flaked corn
10% flaked rice
And about 17 ibu with cluster hops 60 addition and some at 10 if memory serves. S-05 yeast
It fermented low 60's and got one crystal clear beer, but after it conditioned in the bottle it tasted kind of buttery, so I assumed I got a bunch of diacytal and threw it in the corner to see if it gets better. (No slickness in the mouthfeel though)
Fast forward to today and me an SWMBO stop at a local brewpub for lunch and I grab a flight. They've got a new seasonal with peaches. The barkeep somehow didn't know what kind of beer it was other than light ale, so I assume its cream ale/kolsch or similar.
Besides the peach notes it taste damn near identical to my brew. Same odd buttery-ish flavor. Which got me to thinking maybe I'm just tasting one of the ingredients I've never used before (6-row and cluster hops). I would like to assume no self respecting brewery would serve a beer with such a pronounced off flavor, but I know what happens when I assume.

So, did I wrongfully attribute my flavor to diacytal, or did my local brewpub serve up a beer loaded with off flavors?

 

[Pie_Man]

Sounds like diacetyl. Sometimes the buttery flavor of diacetyl can be mistaken with caramel flavors from crystal malts, but given your grain bill, I doubt that is the case.

I personally have tasted plenty of commercial beers with pronounced diacetyl flavors. It definitely happens, typically in smaller breweries where quality controls may lack, or sometimes a demanding production schedule forces a beer out of the fermenter a little too quickly and the diacetyl flavor goes unnoticed. And then of course, some diacetyl is acceptable in some beer styles, mostly English ales.

Underpitching yeast, lack of oxygenation, or transferring to a secondary too early are all common contributors to diacetyl in finished beer. You can also let the beer warm up a few degrees toward the end of fermentation (a diacetyl rest, typically done for lagers). In experience, if you pitch the proper amount of yeast a diacetyl rest is typically not required, especially for ales.

 

[coolharry]

Thanks. I think I just found it out on my own too, haha.
On complete coincidence I stuck one of mine in the fridge last night to check up on it. Just tried it and the buttery flavor is almost completely gone now. It's mellowed to a nice flavor with a slightly sweet finish, just like what I remember from my last spotted cow.
It makes me a bit sad, but this about the 3rd strike for this brewpub now. If it weren't for the food id probably never go back.

 

[Pie_Man]

You can try to mention it to them in tactful manner. They simply may not know. Although that may be a difficult thing to do.

Is your beer bottle conditioned? The extra fermentation that occurs during bottle conditioning can absorb the diacetyl and bring the diacetyl down to acceptable levels, or levels undetectable to your palate. People's palates vary in diacetyl perception and some people don't taste the flavor compound at all. Perhaps the brewer at the brewpub is a non taster for diacetyl...

 

[coolharry]

If I'm ever there when there's a brewer around I would definitely try to chat him/her up. But the location I visit isn't the main brewery so I don't know how often they actually brew there. I've never seen the one kettle/fermenter active. But I'd guess they get the year round offerings from the main brewery and just do a seasonal batch or two on site. Which would probably explain why the one beer was a bit off.
I would have no idea how to bring that up in a respectful way though. I have trouble even pointing out flaws in friends brews.

 

[coolharry]

Oh and yes mine is bottle conditioned. When I first tasted it I swirled all the bottles a bit to rouse the yeast and see if it would clean it up. Apparently it has cleared quite well so far.

 

[SpeedYellow]

Are you familiar with the nasty taste of bad draught beer? I believe that distinctive taste is bacterial infection (probably in the beer lines), so perhaps your beer and the pub's beer were simply infected.