overnight mash and keeping my cool

My first experience with over night mashing was a huge success. Come October I plan on a repeat of a 1c - a little less of the rice adjuncts this go around. If it tastes the way I hope, I'll post the recipe. Cheers for Overnight Mashing!

Stauffbier said:

I typically start the mash at around 158F more or less, and 10 hours later it's at 148F or so. I tape the seem where the lid meets the cooler with clear packing tape to hold in the steam, and then I cover the cooler with a couple thick blankets. I've been happy with the results every time I've done it. I've never had a batch come out too dry, yet.

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Makes complete sense. Thanks for explaining. Certainly 148 would be on the drier side, but by no means dry depending upon starting gravity.

The reason it works is that denaturing enzymes takes time. You won't denature beta amylase (which works at lower temps) in the matter of an hour or two by mashing at even 160 to start with. There will still be some enzymes left once the temp drops into the low-to-mid 150's that will further chew the beer, but not too much. If you WANT dry beer, you start around 153 and you'll get down to just a few points after fermentation. I usually get over 83% attenuation on higher-mashed beers and in the 90's on the lower-mashed beers.

Anymore I find that 3 hours seems to be when things finish converting. I usually mash anywhere from 90 minutes to overnight, depending on my schedule of other things to do, and adjust mash temp accordingly. The 90 minute mashes I use the original recipe temp. Anything in the 3 hour range I bump it up 3-5 degrees (less for lower mash temps, more for higher). Overnight and 3 hours seem to have produced similar results, leading me to believe conversion is pretty much done at the 3 hour mark.

My "Fashionable Late PA" recipe is overnight mashed starting at 153 and dries out to about 1.002...and it's fantastic.

Great info all, thanks for sharing. With a wife, kids, work a house etc. it is sometimes tough to find a solid five or so hours to brew. I have only done all grain and thought about trying extract, but with this idea I think I can squeeze in a few more batches into my schedule. I look forward to giving this a try.

I do BIAB brews. Do you think I could get away with full boil volume and grain mashing overnight in a cooler, and then dumping everything into my bag to separate the grain? Would I need to heat everything up to 170ish for a mash-out before removing grain, or just separate the grain and go right to the boil?

Disintegr8or said:

I do BIAB brews. Do you think I could get away with full boil volume and grain mashing overnight in a cooler, and then dumping everything into my bag to separate the grain? Would I need to heat everything up to 170ish for a mash-out before removing grain, or just separate the grain and go right to the boil?

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I think it would work just fine. I wouldn't bother with a mash out.

Inspired by this thread I am giving this a shot. I do BIAB and have made a jacket for my brew pot out of left over wrap used on our hot water tank. I doughed in last night at 154 for a nut brown ale. I just woke and found the temp at 147. Not too shabby at all. This should be good and I look forward to seeing how this beer turns out. This could allow for many more brews to fit in my schedule.

So far so good. I do BIAB and typically get 70% efficiency. With my 8 hour over night mash I got 78% and my temps stayed above 147 so should be no worries of infection. We'll see in a week or so how the ferment ability of the wort turns out. But I think I am thinking I am going to like this over night mash setup.

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Did my first overnight mash last night. Doing a hybrid Dortmunder Export with WY1007 in the fridge near 55 degrees. Based on recommendations on this thread, started it at 158 and let it sit for about 9 hours overnight in my 10 gallon igloo mash tun (left quite a bit of headspace with only a 1.4 qt/lb ratio - probably should have mashed thinner). It was at 142 degrees this morning. Crazy 83% efficiency with a no-sparge AFTER adding 3 gallons of tap water to the boil. Wort looks great. We'll see about the beer.

I tapped my nut brown ale today brewed with over night mash for the first time. It turned out great and I will not hesitate to mash over night again.

Omahawk said:

Did my first overnight mash last night. Doing a hybrid Dortmunder Export with WY1007 in the fridge near 55 degrees. Based on recommendations on this thread, started it at 158 and let it sit for about 9 hours overnight in my 10 gallon igloo mash tun (left quite a bit of headspace with only a 1.4 qt/lb ratio - probably should have mashed thinner). It was at 142 degrees this morning. Crazy 83% efficiency with a no-sparge AFTER adding 3 gallons of tap water to the boil. Wort looks great. We'll see about the beer.

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SG = 1.062
FG = 1.011

Really dried out (over 80% attenuation) with German Ale yeast. I don't mind - the taste is great.

Omahawk said:

SG = 1.062 FG = 1.011 Really dried out (over 80% attenuation) with German Ale yeast. I don't mind - the taste is great.

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1.011 does not seem that dry. What was the expected final gravity?

On my batches, about 4 total, I get a strange sweetness that's the same through all styles. I'm not getting it on the non-overnight mash. They're not sweet, just a sweet taste.

Anyone else get this?

I've been doing 2 day brews for a year, and the results are very good. My difference is that I complete the mash and sparge and store it in the pots in which I boiled my sparge water.
Kitchen is cleaned and decluttered by the time the bllond gets home. But then, I'm off work at 2.

sudndeth said:

On my batches, about 4 total, I get a strange sweetness that's the same through all styles. I'm not getting it on the non-overnight mash. They're not sweet, just a sweet taste.

Anyone else get this?

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If you're mashing in at a fairly high temp on your overnight mash then what your tasting is likely residual unfermentable sugars. In my experience overnight mashing works best on beers that are complimented by those types of sugars. I don't like to mash overnight on beers that normally would be very dry and/or not at all sweet by style.

So, the wife tossed the old blanket I was using to insulate my cooler mash tun. It was ugly and smelled terrible but it was thick as all get-out and did the job.

Hit the local Sports Authority and picked up a fleece sleeping bag liner. With that I can double it up and it fits the cooler great. Did an overnight mash a few weeks ago and it held temp quite well.

One thing I did find helped, alot, was to pre-heat the mash tun. Last round I tossed two gallons of 190 degree water into the tun about two hours before I started heating my strike water.

I mashed in at 158 and seven hours later it had only dropped to 156. This was a big beer (RIS) with little to no headspace so I know that had to have helped.

This weekend I want to use this technique again to make a Tripel. I'd like to try and keep the tun with the rest of my setup in the garage, which is unheated and local temps are dropping into the 30's overnight. I estimate the garage gets down to about 50 or so. It'll be interesting!

ChrisL_ said:

1.011 does not seem that dry. What was the expected final gravity?

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1.0155 at 75% attenuation.

I've found 1007 to ferment pretty dry. It's a hungry yeast. I have a recipe that I mash low and it brings the fg down to 1.004 regularly!

wickman6 said:

I've found 1007 to ferment pretty dry. It's a hungry yeast. I have a recipe that I mash low and it brings the fg down to 1.004 regularly!

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Interesting. What temp do you mash at?

I'd previously made a Blonde ale and an IPA with 1007, both times mashed 151-152 and had 74-76% attenuation. Since the first several mash hours were in the mid- to high-150s, I was expecting this range or less.

Omahawk said:

Interesting. What temp do you mash at?

I'd previously made a Blonde ale and an IPA with 1007, both times mashed 151-152 and had 74-76% attenuation. Since the first several mash hours were in the mid- to high-150s, I was expecting this range or less.

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Well, for one thing the recipe uses jasmine rice. I think that helps attenuation. I mash that one around 146 typically.

My altbier (actually it's Kaiser's recipe) finishes around 1.010, so more in line with what you may experience.

wickman6 said:

Well, for one thing the recipe uses jasmine rice. I think that helps attenuation. I mash that one around 146 typically.

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As in whole grain rice in the mash? Cool. Any special treatment of the rice required? Cereal mash?

Omahawk said:

As in whole grain rice in the mash? Cool. Any special treatment of the rice required?

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Yep, whole rice. I simmer it until its gelatinous, then add to the mash tun to preheat it. Then add my strike water and grain.

I use a lot of water for the rice, approx 1 gallon per pound of rice.

I'm doing my first overnight mash in quite a while. It's Skeezer's Wookey Jack clone. I decided to do an overnight mash to see if I can increase my efficiency by a couple points, since I get awful efficiency on large grain bills. I'm also hoping to make an extremely fermentable wort, so I can squeeze 80% attenuation out of WLP002. That yeast is rated at 70%, so we'll see how it goes. I have a feeling I will get great efficiency on this, because I accidentally over-tightened my corona mill. My grain was almost as fine as coarse flour. Stupid mistake, and one I've never made before. If I don't have lautering problems I should get a lot of sugar out of this one. I added a pound of rice hulls just in case.
Here are some photos of my tun all wrapped up to keep it warm..

How'd it turn out?

sudndeth said:

How'd it turn out?

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Had a stuck sparge due to over grinding the grain. I had to scoop out the mash and squeeze out the wort through my old BIAB bag. I got higher efficiency than I expected. I just checked gravity today, and I got 88% attenuation on a yeast rated for a max of 70%. That puts my beer at 10.4% instead of the 8.5% that the recipe called for. No worries, because it tastes great. I don't mind the higher ABV. I'll be starting the first dry hop tomorrow night.

I'm giving this a go as we speak. I'll probably mash in at 10:00 PM. I'm shooting for 155' F. I'll add some foil on top of the grist, bring the cooler inside and wrap her in a blanket for the night. Probably fire up the sparge water around 6:00 AM. We'll see what an 8 hour mash brings tomorrow...

masskrug said:

I'm giving this a go as we speak. I'll probably mash in at 10:00 PM. I'm shooting for 155' F. I'll add some foil on top of the grist, bring the cooler inside and wrap her in a blanket for the night. Probably fire up the sparge water around 6:00 AM. We'll see what an 8 hour mash brings tomorrow...

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I'm sure it will work great for you! Cheers!

Foil on the grist is a great idea. When I do five gallon batches my pot is pretty full and holds the temp pretty well, but when I do the occasional half batch the extra airspace in the pot causes a bigger temp drop. I will have to try the foil idea on my next half batch.

Rectangular cooler, foil on top of grist, wrapped up in one blanket (including the bottom).

Mash started at 156' F, 8 hours later it was at 146' F.

My efficiency numbers were a little better than usual. I usually get 75% efficiency. Today it was 80%

EDIT: I forgot to add DME to the boil. Efficiency was 88%!

The mash odor was more pungent, but not funky. No sourness.

After enzymes denature conversion ceases. At 155F alpha denatures in about 2 hours. After enzymes become denatured, over night mashing does little, except for saturation and softening husk. The higher efficiency experienced is due to comparing the usual rest of one hour to an extended rest time. Mash for 2 hours and get on with the brew.

VladOfTrub said:

After enzymes denature conversion ceases. At 155F alpha denatures in about 2 hours. After enzymes become denatured, over night mashing does little, except for saturation and softening husk. The higher efficiency experienced is due to comparing the usual rest of one hour to an extended rest time. Mash for 2 hours and get on with the brew.

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This is true, and it's also why I mash for 2 hours as a general rule. With that said, the main idea behind overnight mashing is not necessarily for raising fermentablity or efficiency. It's more for splitting up the brew day, which is nice if you want to get done earlier the next day. Plus it's just kind of fun..

Exactly. With another child on the way I need to re-arrange my schedule. So, after I put my daughter to sleep I mashed-in and went to bed. Woke up at 5 and was able to finish my brew day before my daughter woke up at 7:30 AM.

Did my first overnight mash last weekend and loved it. Friday night at 9:30 p.m., I mashed in 13 lbs of Pale Malt at 149 degrees in my 10 gallon Igloo Mash Tun. Since I only had to heat the Strike Water, not the Sparge Water, it took half as long to reach the desired temperature. Stirred vigorously with my cordless drill/paint stirrer, shut the lid and put the Tun in the garage. 7:00 a.m. the next morning, the temperature had dropped to 139 degrees. Not bad. started to drain the Tun while I heated another 5 gallons of water for the batch sparge. While I sparged, I started heating the first runnings and added the second and third runnings along the way. Efficiency 83%, not bad. The only things I would do differently are: 1. start with the strike water 2-3 degrees higher. 2. saran wrap or tape the lid on the Tun (alternatively, I think I might look into buying some insulation to cut in a circle and slide it directly on top of the grain in the Tun). I also thought about warming the Tun up with some hot water before mashing, but that means I would have to heat pre-strike water to heat up the Tun. Seems to make more sense to heat the Stike Water a few degrees hotter to warm up the Tun before Mashing. Anyway, great idea and very convenient. Thanks to everyone who shared their experiences with this.

To expand on this idea, how about this:
Mash in at night before bed
Sparge and lauter in the morning
Go to work
Boil, chill, and pitch after work, 8-10 hours later.

Thoughts? If this is plausible. It can really open workday brewing!

Just finished pitching 3711 on a saison, my first overnight mash. I also did no-sparge, to save even more time. It was a 2.5 gallon batch, so 5.5 lbs of grain and 4 gallons of water in my 5 gallon cooler. It only took 30 minutes to heat up the strike water last night then two hours was spent this morning doing the vorlauf, lauter, 90 min boil, chill, and pitch!

Hi all,

I stumbled across this thread today and read it cover-to-cover and there is some excellent tips in here. With kid#2 on the way shortly I thought I would have to take a break from brewing for 6 months in order to keep the wife from killing me. With this technique in my toolbox I'm sure I can pull off a brew here and there without her noticing!

Thanks for the great info and hard work everyone!