Diacetyl Buttery Taste after Bottling

[Aaron_3000]

Hi All,

I'm a fairly new homebrewer. I've done about 10 batches so far (9 extracts) and this is my first AG via BIAB. It's a single malt, single hop IPA that I fermented with WLP001 for 16 days at 60-62F. Before bottling, I took the FG and sampled the beer and it tasted fine. But after about 6 days of bottle conditioning (around 62-64F), I cracked one just to see how it's progressing and I tasted huge buttery flavors and aroma. Some of my earlier batches of IPA's had estery flavors from fermenting too hot so I tried to ferment this one on the colder end. I'm just worried that it was too cold and I had too much flocculation. Perhaps not enough yeast to clean up the diacetyl? It's also strange that it tasted fine before bottling. Now I know that 6 days of bottling conditioning is no where near done, but am I overreacting to this off flavor? Any input is appreciated. It might also be worth noting that I dry hopped 4oz of Mosaic for 7 days before bottling.

Cheers!

-AG

 

[VikeMan]

It's also strange that it tasted fine before bottling. Now I know that 6 days of bottling conditioning is no where near done, but am I overreacting to this off flavor?

More than likely, when you tasted the beer at bottling, the diacetyl level was below threshold, but there was a significant amount of diacetyl precursor (α-acetolactate) in the beer. The precursor has to be chemically converted to diacetyl before yeast can clean it up. This is why some people do a forced diacetyl test before packaging, even though the beer tastes fine.

Now I know that 6 days of bottling conditioning is no where near done, but am I overreacting to this off flavor?

I would recommend keeping these bottles warm, to let the yeast still in suspension continue to reduce the diacetyl. And bumping the temperature up a bit should help. With luck, it may get below threshold, or at least to a more tolerable level.

 

[dmtaylor]

I agree with @VikeMan. In my experience, the diacetyl will typically disappear in about 3-4 weeks on average, if kept warm enough for the yeast to eat it. You've got enough yeast, that's not a concern. All you need now is patience and time. Occasionally it can take a month or two, but maybe 8 times out of 10, about 3 weeks will be good enough.

I would add that hops themselves contain enzymes. The dry hops you added could have generated a little more conversion of dextrins & sugars, this phenomenon is known as "hop creep" and is common with IPAs, so with more yeast activity in the bottle, this is likely part of your problem. But again, this is really just temporary, and over time this will go away on its own.

 

[Aaron_3000]

Ah I see, thanks for the great info guys! Going to warm up the bottles a bit and I tipped each bottle over back and forth to get the yeast roused up a bit.

Just for future reference, is there anything I did wrong to increase the diacetyl in my beer? This is the first time I've fermented at 62F so I'm wondering if that's the issue. I didn't do a diacetyl rest. And the other batches were fermented at 75F so maybe a rest wasn't needed for those.

 

[VikeMan]

Just for future reference, is there anything I did wrong to increase the diacetyl in my beer? This is the first time I've fermented at 62F so I'm wondering if that's the issue. I didn't do a diacetyl rest. And the other batches were fermented at 75F so maybe a rest wasn't needed for those.

Here's a slide from a club presentation I gave a couple months ago.

 

[Jag75]

I always let my beer rise to room temp (70f) at the tail end .

 

[dwhite60]

That will be a completely different beer in two weeks. Six days is not near enough time for them to "condition". They'll change a lot.

Give them time.

 

[Aaron_3000]

Thanks again for all the input and advice guys. So far one of the hardest skills to master with homebrewing has been patience LOL

 

[Aaron_3000]

Hey Guys, just wanted to follow up...

Cracked a bottle after 2 weeks and most of the diacetyl was gone. Cracked a bottle today, at 3 weeks, and it tastes awesome! Getting big hop flavors and can't really detect any buttery taste. Probably the cleanest tasting brew I've made so far. It's my first AG brew so maybe that helps. I turned up the heater in my apartment to keep the bottle temps up closer to 70.

Bottle conditioning does wonders. Cheers!

Aaron