WTH Happened?

[prrriiide]

Brewed a big IPA on 9/2 for a festival. Fermented at 65* for 8 days in primary. Dry-hopped on 9/7. Transferred to secondary to clear on 9/10, held at 48* for 7 days. Kegged yesterday and laid gas to it.

Out of the fermenter, tasted as expected. Dry-hopped then tasted at transfer to secondary: tasted like a killer IPA, hop profile exactly what I want. Today, after 30 hours on gas, it's a carbonated butter bomb. WTH happened? Where did the diacetyl come from? I was obsessive about oxygen uptake in transfers, pitched a huge starter of s-05. I'm at a loss.

The grav finished 5 points higher than BeerSmith projected. Is that it? The unfinished sugars? Or did I pull it off of the yeast to soon? I don't think so; I've only had one beer take over a week getting to FG. That was a 1.102 RIS. I've never had a 1.080 - 1.090 beer take more than a week to hit terminal.

OG: 1.077
FG: 1.016

20g batch
90 min recirc mash @ 148*
90 min boil

15# 2-row
15# pils
9# Vienna
8# Munich 10
3# Cara-pils
2# Crystal 40
2# Dextrose

This beast had a huge hop schedule...1 oz at 90, then an addition every 5 minutes from 60 to flame out, 26 oz total in the boil. 18 additions in all. 14 oz in dry hop.

The biggest question: can I fix this in less than a week, carbonated? I could pitch more yeast into the kegs tomorrow and hold at room temp, but I have no idea what that will do in carbonated beer. Would I get a gusher? I think so...

 

[jekeane]

My guess would be from your account that your beer was at 1.021 or so when you racked to secondary. At that point you began to cold crash but there were still fermentable sugars left so you're yeast that were likely roused when you went to secondary got stressed as the temperature dropped and created the diacetyl.

Butter can also be the result of an infection but I would assume the beer wasn't done when you racked.

 

[Upthewazzu]

I can't say for sure, but my immediate assumption would be that you didn't let it ferment out fully and the yeast were stressed at some point after the primary. I've also read that you aren't supposed to make starters from dry yeast (I can't confirm or deny if that is the scientific truth). Instead, just pitch 2 or 3 packages.

Next time around, try raising the fermentation temp to 68°-70° after 5 days. To fix it you might have to take it out of the fridge and let it warm up. Although, I'm not sure that it's fixable at this point.

 

[schatzke]

Just because FG is reached it doesn't mean it's time to rack it off the yeast. Give them yeasties a chance to cleanup after themselves.

 

[prrriiide]

Thanks for the replies. I am taking it out of the cool box and de-gassing a couple of days to see if it helps.

The 1.016 FG reading was taken at transfer to secondary and temp drop. I checked it at kegging and (as expected) it was the same. At the time I kegged it, it tasted fantastic. It wasn't until I hit it with the gas that the diacetyl appeared.

 

[jddevinn]

The 1.016 FG was the actual FG reading? That would give a 79% apparent attenuation with the Fermentis US-05 data sheet showing 81% aa, pretty close.

S-05 is supposed to be a low diacetyl strain...

During lag and fermentation yeast build amino acids, proteins, ect. Most do not affect flavor but many leak out of the cell. Valine is one of the amino acids produced. An intermediate compound in valine production is acetolactate, however not all of the acetolactate becomes valine. The acetolactate that leaks out of the cell CHEMICALLY in an OXIDATION reaction converts to diacetyl. After fermentation is complete the yeast enter a stationary phase and reabsorb diacetyl converting it to acetoin and subsequently to 2,3-butanediol. Stressed yeast and low O2 concentrations can lead to diacetyl in the final product.

The process to convert the acetolactate to diacetyl is temperature dependent (which is why lagers need a 65°F+ diacetyl rest). Dropping to 48°F and transferring after 8 days MAY have been too soon for all of the acetolactate to convert to diacetyl and get cleaned up by the yeast. After transfer the diacetyl would continue to form from the acetolactate already present without the yeast to eventual convert it to acetoin.

I'd try a warmer temperature rest. If that doesn't get rid of it you could try to add a small amount of yeast and fermentable sugars to the keg (watch the pressure either by bleeding puroticaly or with a spunding valve)



....of course diacetyl can also be be formed by a Lactic acid bacteria, Pediococcus or Lactobacillus.

 

[dmtaylor]

Transferred to secondary to clear on 9/10, held at 48* for 7 days. Kegged yesterday and laid gas to it.

You must have racked the beer a little too early, then kept cold and didn't let the yeast clean up after themselves. Yeast eats diacetyl. But if there's hardly any yeast in there anymore since you racked and kept cold, they can't eat it fast.

You need to warm this beer back up and allow 2-3 weeks for the yeast to eat it. When it tastes good again then you can chill back down and enjoy.

Time and patience are all that's needed. In future, don't rack it, and warm it up at the end of fermentation instead of cooling it down. Seems counter-intuitive perhaps but let me say this, I'm telling you, it works, believe me.

 

[urg8rb8]

Thanks for the replies. I am taking it out of the cool box and de-gassing a couple of days to see if it helps.

The 1.016 FG reading was taken at transfer to secondary and temp drop. I checked it at kegging and (as expected) it was the same. At the time I kegged it, it tasted fantastic. It wasn't until I hit it with the gas that the diacetyl appeared.

Any updates in this?

 

[prrriiide]

Any updates in this?

It's amazing what time will do for a beer. I took this one to a large festival on 10/1, and none of the flavor issues were present; just a slight hint of diacetyl. You'd only detect it if you knew beforehand that it was an issue. Several of the BJCP judges really liked it. It wound up with a high-20s score. In fact, several people told me it was the best IPA at the festival. It did turn out to be damned tasty!

 

[urg8rb8]

It's amazing what time will do for a beer. I took this one to a large festival on 10/1, and none of the flavor issues were present; just a slight hint of diacetyl. You'd only detect it if you knew beforehand that it was an issue. Several of the BJCP judges really liked it. It wound up with a high-20s score. In fact, several people told me it was the best IPA at the festival. It did turn out to be damned tasty!

That's awesome!

 

[smizak]

My beers taste different day to day. It's me, not them.