Dealing with Diacetyl, Question

[Iowa Brewer]

Hi all,

After bringing the temp of my bock up to 66F for 48hrs, I did a diacetyl test I found online and discovered the heated-and-then-chilled sample tasted of butterscotch, hinting at the presence of acetolactate, which would later turn into diacetyl. I'm leaving it now at 48 for a few days to see it goes away. If any of you have any advice I might be overlooking, either on how to proceed or what I might have done wrong, I'd greatly appreciate it.

Here's what I've done:
Jan. 10: Made a yeast starter with WLP833
Jan. 13: Brew day:
- OG was 1.06 (supposed to be 1.068)
- Aerated and pitched decanted starter at 48F and put it in fermenter
Jan. 18-24: Let it naturally rise to 52F and held it at that for one month
Feb. 24: Temp reached 66F for d-rest after a few days of raising it (it's super cold here)
Feb. 26: Final gravity of 1.014 (expected was 1.016) and did diacetyl test

My Concerns:
1. Two brews ago, my beer was ruined by diacetyl. Didn't do the test and I crashed it and removed it from the yeast before I realized. That's how I learned about d-tests and why I did one, yesterday.
2. Have I left things too long so the yeast is no longer able to clean up?
3. Should I cool it back down to 52F and let it ferment for another two weeks before trying another rest?

Thanks for any advice you might be able to give!

 

[RM-MN]

66 degrees for 48 hours may not be enough. If you can, bring the temp up to 72 for another 24 hours and test again.

 

[SoCal-Doug]

For best results, there needs to be some live active yeast to do the d-cleanup. What is typically recommended is to raise the temp above 65F when its at 85% ish of its expected attenuation, then let it finish there. 2 to 3 days after completion of fermentation, go for the cold crash and lagering. If it was done, dead and dormant by the time the temp was raised, there wasn't much cleanup being done. For my lagers, i'm typically raising the temp after about 2 weeks.

 

[Iowa Brewer]

66 degrees for 48 hours may not be enough. If you can, bring the temp up to 72 for another 24 hours and test again.

Thanks, RM-MN! I'll give that a shot.

 

[Iowa Brewer]

For best results, there needs to be some live active yeast to do the d-cleanup. What is typically recommended is to raise the temp above 65F when its at 85% ish of its expected attenuation, then let it finish there. 2 to 3 days after completion of fermentation, go for the cold crash and lagering. If it was done, dead and dormant by the time the temp was raised, there wasn't much cleanup being done. For my lagers, i'm typically raising the temp after about 2 weeks.

Thanks, SoCal-Doug. Hopefully there's still enough active yeast to do the trick. Funny though, as I followed the directions of MoreBeer's website for WLP833, not that they would be the absolute authority, of course.

"We Recommend you make a yeast starter for all lagers. Because of the cold environment you will need about 4 times as much yeast to successfully ferment a lager. If you don't have a yeast starter pitch 2-4 vials at 60-70F and cool to 48-52F within 12-18 hours. To ferment lagers like the German's and Czech's make an active starter of 2000ml per 5 gallons. Pitch at 45-48F and let it naturally rise to 48-52F. Hold your fermentation at 48-52F for 4-6 weeks in the primary. A diacetyl rest is recommended after the last week of fermentation. Raise to 55-58F for 3-5days and crash to 40F. It is normal if lager fermentation takes 3-4 days to show any sign of krausen after pitching yeast."

Would giving the carboy a good shake be worth a try, I've my next test fails?

 

[Dland]

Mostly I make lagers. I pretty much use dry 34/70 or S-189 dry yeast, pitched dry and at 2 packs per 10 gallons, after pumping O2 though, so can not speak to yeast starter & pitch levels.

Starting D rest while yeast is still working is key. I usually try to do it shortly after airlock activity begins to slow, or something like SG 1.020. Shaking the carboy can not hurt, but last time I missed getting a D rest in due to work distractions, I pitched a little 34/70 in and it cleaned it up.

Usually I ramp up from 54F fermentation temp, 3 day D rest at 64, then ramp down and crash.

Another thing to remember is to keep your boil vigorous and don't take too long in cooling wort after boil. Otherwise the precursors to diacetyl can from in wort.

 

[Iowa Brewer]

Mostly I make lagers. I pretty much use dry 34/70 or S-189 dry yeast, pitched dry and at 2 packs per 10 gallons, after pumping O2 though, so can not speak to yeast starter & pitch levels.

Starting D rest while yeast is still working is key. I usually try to do it shortly after airlock activity begins to slow, or something like SG 1.020. Shaking the carboy can not hurt, but last time I missed getting a D rest in due to work distractions, I pitched a little 34/70 in and it cleaned it up.

Usually I ramp up from 54F fermentation temp, 3 day D rest at 64, then ramp down and crash.

Another thing to remember is to keep your boil vigorous and don't take too long in cooling wort after boil. Otherwise the precursors to diacetyl can from in wort.

Thanks, Dland! If things don't turn around, I might give the 24/70 a try. Never used that. Do I mix it with water first, or when cleaning up, should i just pour one pack in for 5gal?

 

[Vale71]

Another thing to remember is to keep your boil vigorous and don't take too long in cooling wort after boil. Otherwise the precursors to diacetyl can from in wort.

You're confusing diacetyl with DMS. They are completely unrelated issues. DMS precursors come from malt and must be disposed of through adequate boiling of the wort, diacetyl precursors come from yeast metabolism and need to be cleaned up by the yeast itself.

 

[SoCal-Doug]

You're confusing diacetyl with DMS. They are completely unrelated issues. DMS precursors come from malt and must be disposed of through adequate boiling of the wort, diacetyl precursors come from yeast metabolism and need to be cleaned up by the yeast itself.

^^^ Yup!

 

[Dland]

Thanks, Dland! If things don't turn around, I might give the 24/70 a try. Never used that. Do I mix it with water first, or when cleaning up, should i just pour one pack in for 5gal?

I'd just pitch it dry, as per mfg instructions. I used one pack split between two 5 gal kegs.