Best Practice for Diacetyl Rest With Lagers

I am very sensitive to diacetyl and a BIG non-fan of diacetyl in beer.

I have brewed well over 50 batches of lager with a variety of lager yeast strains (at least 10 different yeast strains). I have never conducted a diacetyl rest for any of those homebrewed beers and I have never had a batch that had perceptible levels of diacetyl.

The bottom line for my homebrewery there is no need to conduct a diacetyl rest.

I wonder how commercial breweries handle a diacetyl rest? It must require a fair bit of energy to raise the temperature of x barrels of beer from the 40s/50's to the 60's and then bring the beer down to lagering temperature.

Cheers!

 

I too have read the same thing. For example Wyeast 2124 (with emphasis in bold by me):

“STRAIN: 2124

Bohemian Lager™

Species: Saccharomyces pastorianus

Profile: This Carlsberg type yeast is the most widely used lager strain in the world. This strain produces a distinct malty profile with some ester character and a crisp finish. A versatile strain, that is great to use with lagers or Pilsners for fermentations in the 45-55°F (8-12°C) range. It may also be used for Common beer production with fermentations at 65-68°F (18-20°C). A thorough diacetyl rest is recommended after fermentation is complete.”

https://wyeastlab.com/yeast-strain/bohemian-lager

I have used Wyeast 2124 a lot (e.g., well over 30 times) and I have never experienced diacetyl issues with this strain in my homebrewery (and I never conducted a diacetyl rest).

FWIW I have never had any issues reaching my expected final gravity (and I never conducted a diacetyl rest).

I cold crash.

I have never experienced any issues in my well over 50 batches of lager beers.

It would not be prudent for me to recommend that you not conduct a diacetyl rest since your homebrewery is different from mine. But maybe you don't need to conduct a diacetyl rest? I most certainly do not.

Cheers!

 

10-14 days.

Cheers!

P.S. In my opinion, it is the health of the fermentation which is key vs. length of fermentation.

 

Yes siree Bob!

Which is something that ideally you will practice for all of your brewing including ales.

For healthy fermentations:

Pitch plenty of healthy yeast – make a yeast starter for the case of lagers if using liquid yeast.

Ensure proper wort nutrition for the yeast.

Maintain a proper fermentation temperature for the yeast.

Maintain positive thinking during primary fermentation.

Etc.

Cheers!

 

Or conduct a diacetyl rest if you prefer to listen to the beer authors.

I have never conducted a diacetyl rest but for non-commercial brewing I don't see how this would 'hurt'.

Cheers!

 

Diacetyl does not magically disappear within 3 days of warming it up. I don't believe cold crashing is ever helpful unless the beer has already been sitting for many weeks. IF you smell or taste diacetyl, just keep it warm for a good week or two at least before chilling it down. Yes I'm serious. I initiate the rest when gravity points (ignoring the 1.0 at front) are half of original gravity, e.g., when gravity goes from 1.058 to 1.029, it's time to warm it up. This works really well. And then once you are ready to bottle or keg, all bets are off -- the diacetyl might still return. If it does, I find it can take up to 3 to 3.5 weeks for the diacetyl to age out again. Which is fine for me, since I bottle, it's not much longer than the time it takes to carbonate anyway.

I should add: with enough healthy yeast at pitching, you should most often not even need a diacetyl rest anyway. That being said, it never really hurts to do a diacetyl rest in second half of fermentation either, if you want to "play it safe" or whatever. It's never "wrong" to do a rest if you want.

 

First, I'll say that diacetyl is highly yeast specific. If you use WY2007 or 2124 you are very unlikely to have a diacetyl problem no matter how you handle your fermentation. Other yeasts, even a few ale yeasts, are different. Unless I know the yeast very well, my practice is to do a diacetyl rest at 68F for at least 2 days. The one time I did not do this, I made butterscotch beer (was able to fix it by yanking the keg out of the fridge and leaving it at room temp for a few days, but this is not a guaranteed solution). A cooler rest for a longer time would probably yield the same result if you are nervous about getting the beer too warm.

 

Pitch enough healthy yeast, pitch it colder than max fermentation temp, oxygenate well.. you’ll never get diacetyl nor need to do a diacetyl rest. Traditional lager fermentations are actually stepped down at a certain attenuation, not stepped up..lager yeast has the ability to clean up after itself all the way down to freezing if treated well.

The yeast I use presently is usually done by day 6 or 7. Pitch at 46, ferment at 50, let go to 52/53 after 1.020 (day 4 or 5), Leave for a day or two after terminal and start slowly cooling. Probably don’t need to do that but I do. Cool 3-4* per day, leave at 39 for 5 days or so then continue down to 30 for 2-4 weeks.

 

Not unlike what I've been doing of late.
My last Pilsner was slowly brought down to 40F, rest there for a week. Then slowly down to 30F for cold Lagering.