Diacetyl Discussion

On my second Oktoberfest now.
The OG was 1.048.
Chilled to at 65°and infused oxygen for 60 seconds then pitched WLP820 from starter slurry. Shook for 45 seconds.
Waited till the fermentation was very aggressive then gradually dropped the temp to 55°.
I know it is recommended to raise the temp to 68°-70° when the gravity reading is around 1.020 but I was out of town towards the end of the week.
When I checked it last night it was at 1.010. I went ahead and raised the temp to begin the diacetyl rest

Is it too late for a "good" diacetyl rest at 1.010?

I tasted the sample and I didn't get a buttery taste. Tasted quite good actually.

I have seen some discussion that suggests that starting the fermentation at higher temps and then bringing them down helps reduce diacetyl.

Subscribed, because I want to know what people think.

aubiecat said:

I have seen some discussion that suggests that starting the fermentation at higher temps and then bringing them down helps reduce diacetyl.

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Actually I think its other way around. You cool your wort below fermentation temperature and than slowly let it rise to fermentation temp to avoid diacetyl formation to begin with. No diacetyl rest needed this way from what I know.

aubiecat said:

I tasted the sample and I didn't get a buttery taste. Tasted quite good actually.

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Then there isn't any diacetyl in your beer. A diacetyl rest isn't a hard rule when brewing and may in fact never be necessary if one pitches the proper amount of healthy yeast and controls the fermentation temperature. You did good. :rockin:

bgeek said:

Then there isn't any diacetyl in your beer. A diacetyl rest isn't a hard rule when brewing and may in fact never be necessary if one pitches the proper amount of healthy yeast and controls the fermentation temperature. You did good. :rockin:

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You might want to take a look at the forced diacetyl test. It will tell you whether you have the diacetyl precursor, which will slowly turn into diacetyl. You may not have any diacetyl now, but it would be good to check that you won't end up getting it later. A diacetyl rest should clean up those precursors, too, keeping you from getting it later. But, don't bother with the diacetyl rest if you don't have any diacetyl or the precursor.

Basically, for the forced test, you heat up a small sample in a closed container, let it cool, and then compare to an unheated sample. The heat causes the precursor to turn to diacetyl, so you would get a buttery smell if you had the precursor.