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Overnight Mash
Here is a question for you all grain brewers. Have you ever done or know anybody who has done an overnight mash? The reason why I ask is that I am still getting grief over last weekend's brewing session, which lasted about 7 hours. I have heard it is possible to mash overnight, so I figure if I can get my mash going the night before (after everybody is sleeping) that would save me a bit of time the next day.
The trouble would be maintaining temps overnight. It would be best if you could mash and sparge and then save the boil and cooling for the next day. If you mash for 8-10 hours you need to keep the temp above 150F or so to prevent some negative affects on the wort. If you can keep the temp that high overnight it would work just boost it up to 158 or higher the next day to mash out and start sparging.
What kind of negative effects happen if the temp drops below 150?
If you let the temp get too low you're going to create a wort that is almost completely fermentable. So, if your mash were to sit overnight at 143 the enzymes would convert all the starch to highly fermentable sugars and you have the dryest, thinnest beer known to man. If you keep the temp above 150 you won't get much beta acitivity, and the wort should be pretty normal. I'd shoot for 154 and hope it can stay there all night or only drop a couple degrees.
I guess that I thought that after about an hour or so, all the starches were converted anyway, so you pretty much had the sugars formed. Seems like it may be a bad idea. Maybe I will do as you recommended and do the mash and sparge the night before and then leave it covered in my kettle until the next morning. Thanks for the advice.
They would be converted but if you allow them to convert at a temperature below 150 you're going to have completely fermentable sugars, and a dry, thin/weak beer. Let them convert completely at over 150 and you retain some malt flavor and body.
does this mean that if you mash at 150-155, and then leave it overnight, and it drops down to 140 at some point that it will continue to convert starches to sugars? so, starting out at a higher temperature won't make a difference if it eventually drops? i just assumed that once the higher temperature was reached, that it would stop further activity in the lower temps.
It would slow activity but not stop it completely. Time is the key factor, in a standard mash if you go to 155 then back to 140, not much is going to happen. If you start at 155 and go down to 140 and stay there for 4 hours, you'll get excess conversion by beta enzymes, even if bringing the mash to 155 denatured a portion of them.
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