Diacetyl advice needed

[Craig]

I'm keen to get hear if any of you guys have ongoing issues with Diacetyl developing in the Keg. I have this ongoing issue once the Green beer hits the keg.

This following scenario is doing my F%&^$ head in, and I really need some advise, beyond yeast selection, sterilisation and diacetyl rests.

I recently brewed a bit of an Emersons Pilsner (Ale) Clone with NZ ADM Pils Malt and 5% Caramunich 1. To this I added 100% Riwaka hops in three additions. I also used 1469 - West Yorkshire Ale yeast.

Everything seemed perfect. Premo mash, boil and fermentation hitting every target bang on. Temp control was sweat - pitching at 18C, rising to 20C over the first 3 days. I also encouraged it to rise to 22C after a week for a wee rest. The Green beer tasted f'n fantastic straight from the fermenter. Real tropical with passionfruit aroma and taste.

After a total week and a half ferment I slowly dropped it ~4C a day till I hit 1C where it sat for a few days. Then kegged it (no finings). At this point it was still fantastic and a little less yeasty. Still a bit hazy though. I then hooked up CO2 at normal despensing pressure.

Week later couldn't resist a taste. It still tasted good, but aroma seemed to be fading. It appeared to be losing its tropicalness... (I put this down to tempurature initially.)

Another week later and I couldn't smell a thing, but caramel sweatness. And the tropical, hop character was dead in the taste also. I'm a little numb to the whole Diacetyl thing but I think that is the problem masking my once great beer. The beer doesn't otherwise seem problematic.

How can this issue be developing so badly in the keg once on tap. Has anyone else had this problem? Am I not cleaning my lines enough? Should I be dismantling my kegs every time I clean them? Is my vibrating chiller having an adverse effect on the remaining yeast? Am I just going F'n nuts?

Should I try bottling some as an experimental control group...?

[James P]

If it gets too bad just spread it on your toast.... :)

How are you chilling? There is some literature about slow chilling allowing diacetyl precursors to be absorbed back into the wort.

[Craig]

Cheers for all the feedback fellas. Much appreciated.

I must say I think I have had less of an issue with 1056, but cannot say conclusively because I have not compared them in a controlled fashion. My recent 1056 brews were heavily dry hopped with Cascade. Fair to say the hop aroma never faded though.

I have had similar issues with 1968 and 1768. Yeah... maybe I am just a slow learner!

I did make a starter with the 1469 and first pitched it into a Kid Chocolate clone (cheers Stu). It was far less of an issue in that brew, but it was not highly hopped. I repitched a good cupful of slurry from that brew (into 40L) and did aerate with pure oxygen aiming for approx. 8-10ppm. SG was bang on 1.050 and FG hit 1.013.

I always try very hard to minimise hotside aeration.
I drop the Temp inside a freezer that is digitally controlled hence the semi-gradual 4C drop per day.

[JoKing]

With all that in mind - I'm positive that your fermentation was completely normal... I'm much less technical in my brewing than what you have described, and have never had a daicetyl problem. I doubt that you do too.

I could suggest dry hopping with Riwaka at around 2 grams per Liter - this should give you back that tropical aroma you seek. I have done this in the keg many times when I'm unhappy with the fermented beer. It takes about 2 weeks at serving temp for the good stuff to come through... and by the end of the keg.... it's bliss.

[Raffe]

Having some diacetyl issues myself.

First attempt at an APA.
Wyeast 1272 into a 2L starter. 21L of 1.050 wort, fermented down to 1.013 after a week, left it for another week to clean up, finished at 1.012.
At about 19deg for the first week, pushed it up to 20-21 for the last week. Hydro sample before bottling tasted great, no evidence of diacetyl.

However, having opened two bottles after 6 and 11 days, there was in both a noticeable diacetyl aroma and taste, leaving me somewhat confused. The flaw is not fatal, it reminds me more of a cask english pale ale, despite the american hops.

How could have this formed in the bottles? I don't think they are infected. Oxidation, maybe? My bottling process has not changed. I noticed the krausen dropped quite quickly, after the third day, so I did rouse the fermenter occasionally.

Some quick googling suggests the yeast in the bottle may eventually clean this up. Anyone had experience of this? I am keeping the bottles in an alcove in the hall at current Akl ambient temps, so reasonably warm.

[Soren]

Assuming that you're bottle conditioning I would just leave it for a couple of weeks to clean up, could just be intermediate diacetyl from the ferment in the bottle. Could also be oxidation, which can give a flavour very similar to diacetyl...

I noticed the krausen dropped quite quickly, after the third day

1272 will usually be done after 3 days and another 3-4 days to clean up should be sufficient in most cases...

[Raffe]

Thanks Soren. Yes they are bottle conditioned. Would it be worth giving the bottles a wee swirl to re-suspend yeast - would this help the cleanup? I can cold condition later to clear the beer again.

[Soren]

it wont hurt at least, but probably wont do much good either. it might speed up things a bit. I usually shake my bottles as well but only because I am superstitious:)

[Raffe]

One week later, tried a bottle to see how it is going. Significant improvement, the diacetyl is probably only 10% of what it was. Just enough to be noticeable, but the dull sweetness has gone. The hop aroma is not quite as forward as I wanted, but there is a nice flavour balance between the malt and hops, and a firm bitterness. Another week and I hope it will be all cleaned up.

I did give the bottles a wee shake, so I think I will join you on this superstition!

[Steve Nally]

Shopounds like oxidation, the hops are the first to go. You are best to CO2 the keg the lines in the transfer and up the pitch rate of the yeast. When you dry add the hops, pellets i presume, to the beer when it is still fermenting say the last 15% of fermentables. There is enough alcohol to kill bacteria and the yeast will use up the oxygen. This is the problem with dry hopping you are adding oxygen to your beer!
Some yeasts are renowned for diacetyl, it soundn't affect hop character so dramatically...
Try to reduce any splashing/O2 uptake in the mash, kettle and tranfers. When you oxygenate into the fermenter make sure the temp of the Wort is below 26C.

If these things don't work I'm guessin an infection...

Steve