Diacetyl

[Mikey C]

Hi team

I'm having an ongoing battle with diacetyl in my last 3 batches. In an attempt to make sure it doesn't end up in the final beer I've moved from using liquid yeast to using dry yeast. This is to ensure I'm pitching enough yeast (2x packs for 23L batch). I've been extending the diacetyl rest time progressively in each batch to make sure I give the yeast enough time to clean up after themselves. But both of these measures have had no effect.

My latest batch had the following fermentation profile:

Pitched 2 packs rehydrated US05 at 17.5C
Free rise to 20C over 3 days
Raised to 22C at 1.026. Held for 11 days.
Finished at 1.012

I didn't detect any diacetyl from the fermenter sample. I even had a crack at a forced diacetyl test which both my wife and I thought was clear. But after 3 days in the keg it is full of diacetyl!!

I'm picking there is an infection in my beer lines or kegs. I clean the kegs pretty well I think, but the beer lines have not been cleaned for a month or so.

My question is, is there still something I'm missing in the fermentation profile. This profile was given to me from a pro brewer so I'd imagine it's pretty rock solid.

Any help for ideas will be greatly appreciated. This is doing my @#$$% head in!

[Crusader-Rob]

Personally i think its unlikely to be your kegs. as much as it points to that.

the forced diacetyl test can be a difficult one, as the alcohol and other bits in the beer can overtake/overwhlem the senses.

good to see your pitching additional yeast to try and fix it, but i'd also suggest good aeration as well. and depending o nyou OG add more or less yeast.

heres my pitching rates for dry yeast.

1pack up to 1.048

2 packs 1.049 - 1.060

3 packs 1.061 - 1.069

Us-05 is serceptible to diacetyl especially at those lower temps, which people suggest makes the beers cleaner.

the keys to temps are as follows

do not pitch your yeast if above your original ferm temp. pitch at 18 or below, and let free rise to 19

ferments at 19 for 3-4 days and ramps straight up to 21-22 for the remainder of fermentation. let it sit in fermenters for minimum of 14days before kegging or bottling.

the thing is, there are always diacetyl precursors in beer, its just a matter ohw much much remains in the beer post fermentation.

so pitch low with plenty of healthy yeast, rest early and enjoy.

i had the same issue, and mike cheer, gae all the above advice, culminating in a pale ale that received a silver medal in NHC in november.

[Peter Smith]

https://en.wikipedia.org/wiki/Pediococcus   infection from beer lines?  or environment?

I had a urquell last year was amazing from keg but the bottles became gushers and super d bombs...   I think the bottling process was un sanitary    the bottles have just got worse undrinkable butter...

 

[Sam DT]

How was your oxygenation?

Did you add any nutrient?

Heavy dry hop with mot?

[Peter Smith]

How are you transferring from fermenter to keg, how are you sterilising your kegs?

[Mikey C]

Thanks for all the advice chaps.

I aerated for 10 minutes using an aquarium pump. I usually do 20 minutes but read aeration wasn't necessary for dried yeast. I did 10 minutes as a compromise.

I didn't add any nutrient as I used dried yeast. I add nutrient to my liquid yeast starters.

100g dry hop for this batch (50g Nelson Sauvin, 25g Motueka, 25g Pac Jade) so not excessive.

Transferring to keg as anaerobically as possible. Pumping CO2 into the fermenter and filling the corny keg through the keg's out post. Cleaning and sterilising kegs before hand, sterilising with Star San, and not rinsing before transferring beer. Purging the keg's head space after filling.

I'm brewing again soon so I'm going to give my beer lines a bloody good clean in boiling water, then sanitise. Will also lengthen the d-rest a few more days.

[Carl]

For cleaning your beer lines jjust grab some Star LLC (liquid line cleaner). I use a 2L PET bottle with a carbonation/cleaner cap under force to push the cleaner through. I do this between each keg rather than replace the lines since it takes me longer to get the lines onto the barbs with much cussing and mild scolding from heating the lines.