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Overnight Mash, Falling Temps, Fermentability

I’m somewhat familiar with the alpha & beta enzymes, their favored temperatures and how they can affect fermentability in a 60-90 minute mash of near constant temperature.

I’m also interested in trying an overnight mash for the convenience of fitting brewing into a busy family schedule.

What I’m concerned about is the effect of falling temperatures on the mash. I’m guessing in my cooler mash tun I could possibly lose a degree or two per hour. Suppose I started a mash at 154°F and eight hours later it had dropped to 142°F. What would the result be? Are the wort characteristics defined more by the temperature held during the first hour, or more by the final temperature?

I’ve done this many times, and the result is always a very fermentable wort. I usually mash in around 154 and it’ll drop to mid-low 140’s by the next morning. If you want to maintain the fermentability you’d get with a higher mash temp, you need to mash out before you go to bed.

Or start at a higher temp.

I occasionally set my mash up around 11pm-midnight, and then start drawing off the wort around 6-7am when I get up. I start with around 154F usually. I figure most if not all of the conversion takes place within the first hour to 90 minutes. It just sits there until I’m ready to draw it off. It can be down to 138F-142F by morning. I’ve never experienced any difficulties.

Might I suggest another approach? With a half hour mash and single batch sparge I am closing in on a 2 hour brew session. With a half hour boil, I could easily do it just haven’t tried that but I plan to. There’s some radicals pulling off an hour but that’s like a 15m mash and boil and no chill but not ready to go that far.

I have done the research and tested the 30m mash 5/6 times (past year of brewing for me) and it works well. Basically modern malt is modified to allow such a conversion. The key is a fine crush .020". With a single batch sparge I hit 80% efficiency and beer is in the carboy and all is clean in about 2.5 hours. Recently upgraded my mash tun drain to 1/2" line and expect to save another 15m. Will find out in next brew session…

I’ve been doing this recently, due to laziness. My results have been much better than my 90 minute mashes. Mash efficiency has been near theoretical limits ~93% using the same mill gap. I’m able to get my brewday over by 10 AM and on to other important activities.

Greymane what is your process? Done at 10 am , when do you start? Sounds interesting!

Mr. Octabird
American Made!

[quote=“Octabird”]Greymane what is your process? Done at 10 am , when do you start? Sounds interesting!

Mr. Octabird
American Made![/quote]

I usually brew an Amber Rye IPA, with an O.G. around 1.060. This is for a 6 gal batch using the “Denny Brew” setup. After dinner, I fill my hot liqueur tank (44 qt Al stock pot) on the kitchen stove and heat it to 175°F by 11 PM. Mash in thin ~1.3 qt/lb grain at 156°F overnight (higher mash-in temp to compensate for long overnight). Wrap up the little red 48 qt party cooler/mash tun with blankets to hold heat. Refill stock pot on stove for tomorrow morning and go to bed. At 5 AM next morning turn on stove under hot liqueur tank and heat to near boiling, do chores and make breakfast while waiting. At 6:30 AM or so, sparge and collect runnings. Put brew kettle on turkey burner outside and boil wort. Usually all cleaned up by 10 AM.

[quote=“Greymane”][quote=“Octabird”]Greymane what is your process? Done at 10 am , when do you start? Sounds interesting!

Mr. Octabird
American Made![/quote]

I usually brew an Amber Rye IPA, with an O.G. around 1.060. This is for a 6 gal batch using the “Denny Brew” setup. After dinner, I fill my hot liqueur tank (44 qt Al stock pot) on the kitchen stove and heat it to 175°F by 11 PM. Mash in thin ~1.3 qt/lb grain at 156°F overnight (higher mash-in temp to compensate for long overnight). Wrap up the little red 48 qt party cooler/mash tun with blankets to hold heat. Refill stock pot on stove for tomorrow morning and go to bed. At 5 AM next morning turn on stove under hot liqueur tank and heat to near boiling, do chores and make breakfast while waiting. At 6:30 AM or so, sparge and collect runnings. Put brew kettle on turkey burner outside and boil wort. Usually all cleaned up by 10 AM.[/quote]

Great to start and finish early isn’t it? I don’t do overnight mashes, but I love getting up early, starting by 5 and getting done by 9-10M. It’s good to be retired!

Retired guys giving advice to OP with a busy family schedule… :smiley:

Another possible direction: extract. A well made extract beer can be just as good as AG. A semi-local BOP makes KILLER beers and they are extract. Good recipe/good water/full wort boil/yeast starter/proper temps go a long way. I doubt many could tell the difference in typical ales…

[quote=“zwiller”]Retired guys giving advice to OP with a busy family schedule… :smiley:

Another possible direction: extract. A well made extract beer can be just as good as AG. A semi-local BOP makes KILLER beers and they are extract. Good recipe/good water/full wort boil/yeast starter/proper temps go a long way. I doubt many could tell the difference in typical ales…[/quote]

Been there and done that. Extract is too expensive for my taste. I get my base malt $26/55lb sack and that beats socks off extract. Plus, the dog loves spent grain plain, mixed in her food, or as dog biscuits. Got to pinch those pennies until they squeak. :cheers:

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