is a diacetyl rest needs if fermenting under pressure at ale temps?

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

odie

Well-Known Member
Joined
Dec 18, 2016
Messages
2,061
Reaction score
1,169
Location
CC, TX
I'm fermenting a lager under pressure. About 7 psi and 67 degrees. Is a diacetyl rest even needed since my fermentation temps are elevated?

Or can I just leave if alone until it reaches final gravity and then drink right away?
 

Spundit

Insert Witty Comment Here
Joined
Jun 15, 2021
Messages
125
Reaction score
138
Location
Western NY
Typically a diacetyl rest would involve raising the temp and letting it sit for a few days. In your case, I would not increase the temp.... But I always let beers sit for a couple days after final gravity is reached. Just a simple practice to help ensure the yeast have cleaned up everything they can.

If you are in a rush, you could taste the beer to ensure nothing tastes off before you package it. That is always an option.
 

Craiginthecorn

Well-Known Member
Joined
Jan 17, 2020
Messages
253
Reaction score
158
Diacetyl is cleaned up more quickly at ale temps, but certain yeast strains generate more then others. It is possible that you'll have diacetyl or, more likely, precursors remaining. Do a forced diacetyl test. A quick Google search will reveal several articles about it, but regardless of process, I like this suggestion from Josh Weikert of Beer & Brewing to have a control sample:

"From your primary fermentor, draw two samples into two jars and seal the jars. Heat one of those jars (a hot-water bath works well) to about 140°F (60°C). Hold it there for about fifteen minutes, then cool to the same temperature as your unheated sample. Now, smell/taste both. If they taste the same, then you’re in the clear! There’s likely very little chance of a meaningful diacetyl flavor. However, if the heated beer tastes strongly of diacetyl, you should let the yeast continue to work on it (and maybe increase the temperature a bit to goose the yeast cells into activity)."
 

cactusgarrett

Supporting Member
HBT Supporter
Joined
Apr 8, 2008
Messages
2,267
Reaction score
857
Location
Madison, WI
Facetious answer: it's needed if it's needed.

Whether diacetyl (precursors) is generated (and how well it's cleaned up) depends on everything that goes into the recipe: process as well as ingredients. You don't know for sure if a d-rest is needed unless diacetyl is actually present. That said, to do it is easy insurance.
 

DuncB

Well-Known Member
Joined
Jun 5, 2019
Messages
2,673
Reaction score
1,542
Location
Paremata New Zealand
Agree good insurance to do it, don't be scared of bumping the pressure up, if near end of ferment set spund to vols target for that temperature.
 

Latest posts

Top