View Full Version : diacetyl-vdk/rest profiles

02-01-2006, 10:37 PM
ok guys im looking for everyones input on there diacetyl/vdk rest profiles for ales/lagers
currently on ales we are running about three to four days to complete fermentation then rest for 36 hours at ferment temp. drop to 55F for 24 hours then 40F for about four days then 32F for about two days and then we filter
on lagers we ferment at 58f untill about 6PLATO then drop to 56F, at 4PLATO drop to 50F, three days after bunged we slowly drop down to 32F for about a week these fermentations take about one month

this lager yeast is a cz pilz
our ale yeast is a house strain that is basically a west coast ale/california ale strain

i would like to get some ideas on diacetyl removal and am looking to find out how everyone else does it
also does anyone knows about dms removal besides a getting better boil
thank you

02-02-2006, 06:02 AM
my procedure is to primary ferment until I'm 80-90% within terminal gravity, then a 48 hour rest at 55-60F. I test for diacetyl by gently (and indirectly) warming a sample until just before 90F, then sniffing mightily, any traces of butter or butterscotch let me know that the yeasties haven't finished their VDK reduction, so I rest another 24, retesting until I get a negative. Crash to 33F for 3-4 days and then filter (if needed), carb and serve! :)
For every brewer, there's probably a different method, but try a few and modify as suitable for your needs/brewhouse/beers -- cheers!


02-02-2006, 07:18 AM
The first brewer I worked for did a very similar procedure as you, eelbrewer, but another brewer I worked for(whom I really trust with the technical stuff) said Diacetyl will be taken up if over 68 deg. F. Now that I am in charge of the whole brewhouse, here's what I do with good success. Ferment at 69, takes 4-5 days. Let it sit at that temp for 1-2 days more and slowly crash to 34 degrees. I usually take 2-4 days to get it that cool. Now, is it my extended rest at 69 that gives me no diacetyl or is it the slow move through the 50's. I've heard both sides. Either way, I don't have any problems. House yeast is London Ale yeast. We also don't filter (very flocculent yeast), maybe that has something to do with it. I'd like to know the "right" way.

02-02-2006, 08:24 AM
The viability of your yeast will also play a big part. Make sure that your pitching rates are sufficient, try using a commercial yeast nutrient (we use YeastX from Crosby Baker), and try letting the beer warm up slightly towards the end of fermentation. You might also try not capping off the fermenter until you are sure the diacetyl is removed.

02-02-2006, 11:33 PM
VDK rest is best carried out at fermentation temps, the warmer temp speeds the conversion of VDk's into flavorless compounds. This being said, you need to create the VDK's and then reduce them down to flavorless compounds. There are two keys to this in my experience. First and foremost, a healthy yeast pitch with proper aeration is a good defense. Second, make sure you do a proper 24-48 hour rest, I go 48 every time just to be safe. Also, I do a 5 day maturation period at cellar temps (55F) and then crash cool before filtering or transfering. Make sure your yeast harvesting procedure is up to par, selecting for healthy yeast pitch after pitch. If you run too many generations, you might be selectilvely harvesting weak, defecient yeast that lose the capacity to convert young beer fllavors (VDK's) and thus have a diacetyl rich beer. Also, make sure this is truly a fermentation issue. Poorly maintained beer lines will give a diacetyl taint to beer, no matter how long you rest the beer or pitch healthy yeast! Rob makes a great point on testing your beer, because as well as I think 24-48 hours is good enough, I have had a batch that I tasted warmed up, found the big "d" and then extended my rest to 72 hours and found it went away. The bottom line is taste your beers every day and know where they are, 99% of my beers are great for the big "d" in 48 hours, but there is always that one that is not, and only by tasting it could I find that it needed another day or two. This is also a great chance to find out that maybe you don't want to harvest yeast from that Fv because maybe there is something going on there that you don't want to pitch forward.

Larry Horwitz
02-03-2006, 10:17 AM
Primary waaaaaayyyy lower than 58F for your pils yeast and you will get less VDK at the end of the ferm. Chezk pils yeast loves temps around 50F. Also, let your lagerss wrm up into the 60s for a D rest and you will see a much more efficient reduction.

03-02-2006, 12:46 AM
This depends mainly on your main fermentation. If you have relatively low tempertures during main fermenttion (6-8°C) you should not have any problems with Diacetyl. With higher temperatures you should either have pressure fermentation or should keep a diacetyl rest (at approx. 12 -15°C for 1-3 days). What also helps is krausening up (with young beer where the yeast is in a high krausen state). In pub breweries you should not have a problem with diacetyl (when you DONīT filter your beer) since beers in pubbreweries still have enough yeast in the final product.

My two cents.



03-08-2006, 04:42 AM
As a matter of fact, that's what's "wrong" with Pilsner Urquell. Let me hasten to add that I think the diacetyl at the level found in their beer adds an interesting facet to the maltiness of their beer and is therefore a large part of its character. The yeast drop out (or are taken off) before the 2-Acetolactat becomes diacetyl, which the yeast normally gobble up, but since they're not there anymore, the diacetyl remains in the finished beer. So if you want to brew a real Pilsner Urquell-style Pilsner then don't do a diacetyl rest... :)