Overnight Mash

[Bribie G]

I did a stovetop cereal mash with 1500g of maize for my new batch of American Malt Liquor. Then while waiting for the stockpot to cool to dough-in temp so I could do the main mash, I got diverted by Age of Empires and by the time I had defeated the red and the green guys, I looked at the clock and realised that I had set myself up for a two AM finish. I prepared the main mash (Galaxy, Carapils, Melanoidin) and poured in the cereal pot, hit 67 degrees and just wrapped the whole lot up in a sleeping bag and doonah and went to bed.

That was 11 pm last night, I got back to it at 9.30 this morning and it was still at 60 degrees bang on. Seven degree drop over 10 and a half hours. No complaints there. Currently boiling, wort tastes just fine. It will be interesting to see if it attenuates more than a short mash, as it's been in beta Amylase teritory overnight, although with a dough in at 67 this might compensate a bit. With the style, a drier finish and more alc might be an advantage anyway :icon_drunk:

:icon_cheers:

 

[MeLoveBeer]

I've been interested about the effects of prolonged mash times myself and would love to know how this one pans out; I've been brewing with Maris Otter a lot lately and a few people have mentioned that results improve with a longer mash time (2+ hours) and longer boil.

TBH, I've never given it a crack, but would love to know if there are any negative effects first.

 

[Bribie G]

I've found a very informative post on the U.S. BrewBoard forum that answers all of my questions :icon_cheers: Might pop a bit of calcium in next time but it sounds like the guy on BrewBoard has got the system by the knackers

 

[aaronpetersen]

Braukaiser did an experiment with longish mash times here. Wasn't as extreme as your 10 hour mash Bribie, but he clearly showed increased attenuation with longer mash time.

 

[MeLoveBeer]

Not a bad read... can't see the harm then. Didn't all grain mashing start out with everyone doing overnight mashes anyway?

 

[mxd]

I did a 4 hour mash last weekend (family pub lunch for birthdays), so I mashed in just before we left, then mashed out 4 hours later when we got home. The drop in temp was about 3 degrees. Efficency etc.. similar to normal.

 

[Bribie G]

Braukaiser did an experiment with longish mash times here. Wasn't as extreme as your 10 hour mash Bribie, but he clearly showed increased attenuation with longer mash time.

I've bookmarked that Braukaiser site, great resource :icon_cheers:

 

[MarkBastard]

Don't you risk the mash going sour?

 

[Bribie G]

Don't you risk the mash going sour?

If you left it lying around at room temp for a day it might do, the guy on the other forum says:

Q: Shouldn't I be worried about bacteria?
A: Not really. Many beer-spoiling bacteria, including lactobacillus, don’t survive a mash very well. Most lactobacillus strains cannot survive temperatures above 140F. Some of it will indeed survive, but usually very little; this is the reason most people suggest adding fresh grain to a mash once it drops below 140F when creating a sour mash. Any bacteria that survive the mash will be killed in the boil anyway, so that's not a big problem.

As I mentioned before there are some bacteria that could potentially cause off-flavors even after the boil, but I have never personally encountered them. It is not likely that most of them would thrive, or even grow, unless the mash temperature dropped too far below 140F or 130F, and as long as your mash tun is insulated properly this should never be an issue.

Sounds reasonable.

 

[bcp]

I wonder about whether you're likely to get more tannins leaching out over a longer period. Just a question, really, no basis for it other than soak anything long enough and osmosis happens.

I supposed if you control alkilinity it would reduce that effect.

 

[argon]

hmmm... very interested in this. Would love to do the opposite and wake up in the morning... mash during the day while at work, then get home and finish it off.

 

[jbirbeck]

there have been a couple of threads on here about overnight mashes as well. I've looked into it a few times as it really would be ideal for me in a lot of ways. the problems I have had is I get too much temp loss over the course of the mash to consider mashing for anything longer than 2 hours. Now once the RIMS is up and firing it would be a different story.

 

[Kai]

Yes spoilage organisms will survive the mash, and a mash can reek to high heaven if it spends a night at ambient temperatures.

If I was leaving a mash overnight I would put a little extra load on my fridge's compressor and chill it right down for the night. No chance of spoilage and no worries about over-attenuation.

Your strategy sounds great for malt liquor though, bribie.

 

[beerbrewer76543]

It is recommended to keep food out of the 4 to 60*C range as this is where bacteria multiply the best

So an extended mash should be ok in terms of bacteria if kept over 60*C

 

[bullfrog]

I need a bit of clarification here; does one need to hit beta amylase mark, and let it do its thing before hitting alpha amylase territory for a successful stepped mash, or will it work as effectively in the reverse? I always stick to a mid-range of the two with a mash temp of 66 degrees, but could I do a reverse stepped infusion in that I start high and bring the temp down over some time, as Bribie has done, with the same end-result as a traditional stepped mash?

 

[haysie]

I dont see any problem with an extended mash. I have done it and it didnt stink, wasnt sour nor was it infected. I mash out fairly easily from a 2.5tr > 1kg though. DMS issues maybe a worry though with this method.

 

[Kai]

I dont see any problem with an extended mash. I have done it and it didnt stink, wasnt sour nor was it infected. I mash out fairly easily from a 2.5tr > 1kg though. DMS issues maybe a worry though with this method.

Your boil should evaporate it off.

On keeping temps high overnight, if you can manage above 60 all night then that's great. I know my mash tun is nowhere near insulated enough to keep that sort of heat in. Otherwise, yes you do still have live bugs in your mash and yes it can make it go funky. It might not, but it might. I've had spent grain left sealed up in the mash tun for a day or so stay fine, but I've had it projectile vomit, spin heads and crawl on the ceiling too.

Also worth pointing out that a mash kept warm overnight might darken the wort a fair bit. Maybe worth avoiding for that extra pale classic american pilsner?

 

[hirns]

I've done this in reverse... but still going to bed a 2am. I've mashed in at 12pm and then been distacted by the taking the kids to swimming, soccer, shopping... getting home at 4pm... Sh.t, promised to take them to the speedway. Come home and sparged and boiled to finishish at 2am. Mash was 55ish if I remember correctly. Beer was very good. Would not think that the food bacteria issue below 60C is too much of an issue hear as you are then boiling it for at least 60min.



Hirns

 

[raven19]

I've had reasonable reports from my Span of the Decades RIS as per linky here.

Nice work Bribie, I found no issues arising from an overnight mash - like you said, wrap the esky up and set the alarm the next morning

 

[RdeVjun]

Another vote in favour of overnight mashing, have done this several times with no ill effects, just a slight to moderate increase in attenuation, which I guess would be ideal for the malt liquor. It works in quite well if you're pushed for the single big block of time on brewday, it can be split into two smaller sessions with a welcome rest in between. :icon_cheers: