Your Fermentation Schedule w/ Diaceytl Rest

[Alphaacid]

Can you guys describe your fermentation process in detail. I am trying to figure out after I reach terminal gravity if I drop to 50-60F, rack the yeast off, leave the beer in the fermenter for a day or two (diacetyl rest) then transfer to brite tank from the bottom of the fermenter, or the racking arm? I've done it both ways, and pulling from the bottom of the cone I tend to get sediment sliding down the side of the cone and getting transferred to brite tank. Or if I transfer after pulling the yeast out of the fermenter, I leave a pile of beer at the bottom of the cone that the racking arm can't reach. Not really sure which way to do it. I'm guessing leaving a leittle beer at the bottom of the cone is better then transferring stuff over to brite tank.

Are you dropping the temp when you get close to terminal gravity, or are you just letting the yeast attenuate until it's done? My terminal gravity is always off by a point or two, and I'm not really sure how to hit it every time.

[beerchemist]

Usually a diacetyl rest involves allowing the beer to warm by a few degrees F just as it's coming to the end of active fermentation. If you were to instead cool the beer down, that would definitely inhibit VDK reabsorption.

[Alphaacid]

Well 1/3 of the way through fermentation I allow it to free rise up 3-4F to reduce VDK.

[beerchemist]

Are you experiencing unacceptable levels of diacetyl with this method?

[soia1138]

What is your actual question? This one is multi faceted. Get a little more specific with the issue you want to resolve.

[Alphaacid]

I'm not experiencing diacetyl with this method. My question is: at which point during fermentation is VDK removed?

[jebzter]

The yeast are constantly producing acetolactate(precursor) and then reducing diacetyl. During growth and fermentation the yeast are producing more than they are reducing, when fermentation slows, diacetyl is reabsorbed into the yeast cell and reduced to neutral compounds. The D-rest should come at the end of fermentation, in my experience, the warmer fermentation temps of ales do not require a temperature change, but just an extra day after final gravity is attained. Lagers are a different story, the colder temperatures slow the formation of diacetyl from the precursor and thus require a warming and some more time. If you are having excessive diacetyl, look into your yeast nutrient and FAN, insufficient valine causes the yeast to produce their own, and this is where diacetyl comes from, unless its an infection. So to answer your question, the rest should occur after final gravity is attained, but do not reduce temperatures.