split brewday - efficiency and fermentability

[jaroporter]

been reading lots of posts recently about mashing overnight to break up the brewday into more manageable parts, so i decided to have a crack with my last full volume brew. i'd read that it could lead to a drier beer due to added fermentability, and that i might even increase my efficiency, but i was a bit surprised by just how much this seemed to happen..

grist was 100% pale malt (so fairly fermentable by any account), mash temp at dough in was a lower than usual 64C (but still a fairly standard temp, no?).
efficiency smashed into the 90s from my usual ~80-2%, allowing me to brew more at a higher OG of 1,052 (this was a very rustic brewday and there was lots of off-the-cuff decision making regarding recipes and basically everything else)
but more surprising was the attenuation of the yeast. the main batch i pitched rehydrated nottingham into, and this took it down to FG 1,003! tastes fine so i have little reason to suspect any foul play, and the offshoot batch i pitched with rehydrated NBS saison yeast made it down to 1,001, so it's consistent..

got no reason to suspect dodgy hydrometer - indeed it tested fine in water - so i just gotta ask if anyones had any similarly notable experiences with mashing overnight?

[fego]

I reckon you created the perfect storm there for such a dry beer and the overnight mash would probably have contributed the least to it in my view. Your mash temp would have resulted in a dry beer even in a 60 minute mash, especially with no crystal/unfermentable malts.

I've done a few overnight mashes but always deliberately compensated with a higher mash temp and sweet malts. I have only ever noticed better efficiency which is what you would expect.

[jaroporter]

yeah i reckon there is efinitely something in that. i hadn't planned on such a low mash temperature, but wasn't worried enough to care that specific day. but having mashed at different temperatures (65C-69C) with all pale grists before i still find it surprising that a couple of degrees could have contributed so much to the final gravity. i've not previously had an ale/lager finish anywhere near that low - so i just wondered if the lengthy mash might have contributed some other way.

either way, i planned for a session pale and i got a knockout (6,5%) dry ale( ). so i'm gonna have to play around with these split brewdays..

[gregorach]

yeah i reckon there is efinitely something in that. i hadn't planned on such a low mash temperature, but wasn't worried enough to care that specific day. but having mashed at different temperatures (65C-69C) with all pale grists before i still find it surprising that a couple of degrees could have contributed so much to the final gravity. i've not previously had an ale/lager finish anywhere near that low - so i just wondered if the lengthy mash might have contributed some other way.

either way, i planned for a session pale and i got a knockout (6,5%) dry ale( ). so i'm gonna have to play around with these split brewdays..

If you don't raise the temperature enough to denature the enzymes at the end of the mash, the beta amylase is just going to keep going, breaking the long sugars down and making the wort more fermentable. If you're going to do that, you need to up the mash temperature to compensate.

[dean_wales]

WOW! I like this as an idea for achieving a drier beer without using simple sugars to 'dry it out' such as in high gravity Belgian ales.

Maybe I could try an overnight or 24 hour mash for my next big tripel or quad. Hold back on the sugar until late in fermentation to see how much attenuaton I can get. Thats some great efficiency/attenuation youve had. Not that I would want that in many classic English ales.

For a big beer. Surely a dry all malt brew has got to be more appealing than one made with malt/sugar?

Dean.

[jaroporter]

cheers for the response Dunc, the science makes sense, guess the extremity of the consequence surprised me just. that's just helped make the connection back to the vague bit of learning i did on mash chemistry and temperature rests a while back.
so to clarify, if i wanted to avoid the beta-amylase doing it's thing overnight, and still keep a hands-off single infusion mash, i presume would i have to mash in above 68C to make sure most of it (all of it?) is denatured before leaving it such a long time?

and Dean it's certainly got me thinking along those lines, though this was such a surprise i'd worry about my imperial ipas losing body! there's maybe room for a little experimenting with different mash lengths then.. who knows, maybe we'll find the 7,5 hour mash at 64C will become the new alternative to step mashing!

[gregorach]

Yeah, mashing in at around 68 should probably do the job.

[minesapint]

A full mash brew takes me about 11 - 12 hours .
That includes weighing grain and chemicals, setting up the polythene greenhouse in the back garden for the boiler, mashing, sparging, boiling, very slowly draining the boiler and finally cleaning everything up and putting the greenhouse away.

I never put that amount of hours in when I worked full time!

I now mostly have a double brew day and split the task. I find it's more leisurely.

I have not noticed any difference to the final product but in the book "Home Brewing" 2nd edtn. by Graham Wheeler, page 9, he says
"The wort must NOT be allowed to cool before the boiling phase otherwise off-tastes and hazes may be produced in the finished ale."

I actually sparge the mash on the first day so I have stopped the process and have lidded buckets of sweet wort going cold overnight, awaiting the boil next day.

Does cooling really affect the brew or is it just professional brewers not wanting to waste money heating up hundreds of gallons of sweet wort a second time ?

Any one noticed any difference? I don't.

Cheers all.