Diacetyl infection - advice needed.

Buttery taste/smell isn't usually an infection. Diacetyl is an intermediate fermentation product produced by yeast (amount depends on yeast strain, how much yeast was pitched, yeast health, fermentation temperature etc). Eventually the yeast usually clean it up. If fermentation is nearly done, raise the temperature a few degrees and let sit for another 10-14 days. It should nearly go away...if your off flavor is diacetly.

Opps, I didn't realize you had already bottled. You may be out of luck. Best you can do is don't touch the bottles for a few more weeks and try one again. See if it improves.

 

If you are storing the bottles in the fridge, I would just pull them out and let them warm up with the hope the yeast in the bottle will clean things up. Warm conditioning is probably the only chance to resolve it now.

 

Yes

You should give homebrew more than a week of bottle conditioning before you start thinking about dumping the batch.

 

If warming them up to try to get more fermentation going doesn't work, then it could be an infection. Ped can produce diacetyl, but in my experience that doesn't typically show up until around the 3 month mark. So if your beer isn't that old then it probably isn't an infection. If conditions were very unsanitary and a lot of ped was introduced then it could probably happen sooner. Also, if it is from an infection, it won't go away with time. But it will change with time. Personally I like to keep these types of beers and sample them every few months to see how it changes.

Also, in the future I would skip the secondary. What method did you use to sanitize your bottles/buckets/tubing etc..?

 

Leaving the bottles at room temperature should be fine. What temperature did you ferment at? Colder temperatures can slow or inhibit the yeast from cleaning up fermentation by-products.

Also, depending on gravity, you may want to leave the beer in primary/secondary a bit longer. And typical advice for bottle conditioning is to leave it for 2-3 weeks.

 

If there was Diacetyl precursor in the beer, and you exposed it to O2 when bottling, then you produce diacetyl. If the yeast is not active enough to take it all up, it won't go away.

 

You should always use an airlock, even in secondary. There is still a minute amount of fermentation going on and pressure is building. You're lucky you didn't have a carboy bomb--very dangerous.

But I'm not sure that it fizzing over introduced O2. Usually that happens when racking/bottling if you're too splashy with your process.