overnight mash and keeping my cool

I've done exclusively overnight mashes and/or 3 hour mashes since I found out it was possible. Here are some basic findings through 5-6 batches:

Mashing at 153 will produce a beer so dry it will nearly hit 1.001 with an aggressive yeast like US-05. I got 95% attenuation on this PA.
Mashing at 156 produces a medium-to-dry bodied beer. This is kinda the cutoff point. Below this and you'll dry out from not denaturing enough beta.
Mashing at 158 is what you want for more full-bodied, malt-forward beers.

The last two mashes I did were in the 3 hour vicinity and my efficiency was the same, 80%, just like every brew I've done overnight/3+hours. My equipment did not change and previously I was in the low 70% range.

In my Coleman Xtreme 70qt cooler I lose about 10* overnight, ~8-9 hours. It keeps temps for the first few hours without much drop at all. It seems to lose temps near the end of the mash.

I detect nothing different about my beers, but you must adjust your mash temps accordingly, as per above or your experience. A recipe that calls for a 150 mash, do 153. 154, do 156. 156 do 158-160.

The Pale Ale I made that dried out to 1.001 was fantastic. It was dry (6%) but not alcoholic at all and the hops shone through wonderfully. It's in my recipes.

Lastly, this can be used as an "all day mash", too. Get up early, strike and dough-in, cover it and do what you gotta do. Come back at 4PM and finish up the sparge/boil while you have a few homebrews.

Something else I'll add if it hasn't been mentioned... The less headspace you have in your MLT the better it maintains temp, so I mash thin. As much as 1.75q/lb. I've also done a "no sparge - over night mash", which turned out to be very good beer.

Stauffbier said:

Something else I'll add if it hasn't been mentioned... The less headspace you have in your MLT the better it maintains temp, so I mash thin. As much as 1.75q/lb. I've also done a "no sparge - over night mash", which turned out to be very good beer.

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Yep. I play with mash ratio until I get the same strike and sparge volumes. Makes remembering my volumes easier, ie. I put 6.6g in the HLT for strike and 6.6g in the HLT for sparge. Simple. Usually I end up around 1.4-1.5g/lb.

I need to put foil over the top of my grist once and try that, too. I'm told that works wonders for heat retention.

I wouldn't worry about infection pre-boil. Remember, the boiling process sterilizes everything.

When they brewed in the dark ages, they used pond water, and the brewing process "magically" made undrinkable water, drinkable.

I had a mess of a mash this weekend on a russian imperial stout. I kept sparging after i collected 5 gallons at 1.100. I collected another 4 gallons and brought to a boil (kill the enzymes) and then kept at room temp until I was ready the next day for a 60 minute boil. So far, so good (1.054 of the 2nd 4 gallons).

Hope that helps,

Kegged my accidental overnight mash this morning, tasted fine. 1.012.

Heine81 said:

I wouldn't worry about infection pre-boil. Remember, the boiling process sterilizes everything.

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This is true, but if your mash drops below 140F lacto can set in and sour the wort. You can boil out the lacto, but you can't boil out the sourness...

This was what I was worried about--I was well below 140F overnight. But while kegging tasted fine.

Stauffbier said:

This is true, but if your mash drops below 140F lacto can set in and sour the wort. You can boil out the lacto, but you can't boil out the sourness...

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My 153 OvM ended up just a scosche above 140 by morning. It turned out fine, but again, I wouldn't want to get below that. Using a cooler and blankets is key. Higher water/grist ratio helps and I'm told putting foil over the grist does as well.

Has anyone mashed overnight with temp control? I'm thinking of trying with an electric biab set up and an auto stir, not sure of what temp to set paid at?

Jem said:

Has anyone mashed overnight with temp control? I'm thinking of trying with an electric biab set up and an auto stir, not sure of what temp to set paid at?

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Yeah, I've tried it. Well....... sort of. I used a heat blanket under my MLT! haha... It actually worked pretty good. It was winter, and my house gets cold (bad insulation - old house). It kept me above 146F after 12 hours with an initial mash temp of 155F.

The 140F thing is pretty much the "cut-off" point for the danger zone, but I'm sure it would be ok if it dropped below that if it were only for a short time.

My first attempt dropped to 138 if I remember correctly. I have no idea how long it was that low, but I had no sourness in the finished beer. Obviously not ideal, but it worked out that time.

Thanks to a few great ideas from some of you, such as using foil/saran wrap to seal up the cooler and mashing a bit higher than recipe calls for I'm sure that 138 won't be an issue anymore.

Mashing higher is a must. As I've mentioned, you won't completely denature all of the beta amylase, even in a higher mash, so as the temperature drops and alpha goes to sleep, beta will keep chewing up chains, resulting in a highly fermentable wort. Like I said, add at least 3 degrees to recipe mash temp.

I did a first time overnite mash with a 12 gal batch of Strawberry Blond. I did it because of time constraints more than anything. It was just easier to split the mashing on one day and the boiling the next morning. My temps dropped 14*F in about 10 hours. I was pretty happy with that. I ended up hitting my OG dead on and no issues followed as far as mash efficiency. Only issue I had was cooling 12 gal of boiling wort. That took for about 1.5 hours due to not having a CFC which I need to get. My immersion chiller is great for 5 gal batches but I need something better for 10+ gal brews.

beerloaf

What temp did recipe dictate and what temp did you do?

I'll be mashing in tonight, EdWort's Haus Pale ale. Gonna give it a shot at 158 and see where I get.

I brewed the same recipe last weekend mashing at 152 for an hour, so I'll have a good side by side comparison as to how the temps work differently based on mash time.

wickman6 said:

I'll be mashing in tonight, EdWort's Haus Pale ale. Gonna give it a shot at 158 and see where I get.

I brewed the same recipe last weekend mashing at 152 for an hour, so I'll have a good side by side comparison as to how the temps work differently based on mash time.

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I'll be very interested in hearing about the results. I almost did an overnight mash tonight, but then I got invited to the bar. So much for that idea...

Stauffbier said:

I'll be very interested in hearing about the results. I almost did an overnight mash tonight, but then I got invited to the bar. So much for that idea...

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I hate when that happens...lol

I mashed at 157.4, close enough. Dropped to 145.7 in 6.5 hrs, used the saran wrap method this time coupled with blankets. I'm happy with that. Kitchen smelled glorious this morning!

I have access to some heavy duty plastic foam stuff that car bumpers are packaged in. I think I'm going to mahe a sleeve for the cooler that I can just slip over it. It would be reusable. I'll post pics once I get around to making it.

making a muncher helles tonight/tomorrow, overnight mashing of course. im shooting for 157 tonight and hoping to attenuate from 1.051 to 1.012 or so. i might be upping my mash temps even more lately as ive had some dry beers even with the increased temps.

Set up two 250 watt light bulbs in reflectors and put them 12 inches away from either side of your mash tun. This will stop or minimise heat loss. If it results in a heat gain, so what? you will have at least an hour at 66 deg C then a slow rise to say 78 deg C - perfect, now sparge and get it boiling. If this is already covered in one of the 57 posts,,, sorry ! and sleep well......

BOBTHEukBREWER said:

Set up two 250 watt light bulbs in reflectors and put them 12 inches away from either side of your mash tun. This will stop or minimise heat loss. If it results in a heat gain, so what? you will have at least an hour at 66 deg C then a slow rise to say 78 deg C - perfect, now sparge and get it boiling. If this is already covered in one of the 57 posts,,, sorry ! and sleep well......

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I wonder how well this would work with a cooler, though. Perhaps if I built a foam-board cover (like a box with no lid) and put it over the mash tun with the light bulb(s) underneath, this might work. Interesting idea.

So I missed my mash temp being cocky and figuring I didn't have to heat my strike water (which I also use for pre-heat) all the way to 185-190, instead transferring it to the MLT at about 180. Well in 5 minutes of pre-heating it dropped to 168 and that's the low end of where I wanted to dough-in. Ended up with mash temp of 154-155 initially, which was below the 157 I was shooting for. Good thing this is a Munchener Helles and finishing on the dry side is OK for a sessionable light lager. I'm guessing I'll go from 1.051 to 1.008 or so. Dry, but not super dry compared to my FLPA beer that finishes near 1.002 mashed at 153 overnight.

tre9er said:

Mashing higher is a must. As I've mentioned, you won't completely denature all of the beta amylase, even in a higher mash, so as the temperature drops and alpha goes to sleep, beta will keep chewing up chains, resulting in a highly fermentable wort. Like I said, add at least 3 degrees to recipe mash temp.

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Based on the above, I just did a batch mashing in at 158 F at 9:00pm and I took a temperature reading at 12:00pm the next day and I was at 143.7 F. I'm using a Coleman Xtreme cooler and BIAB. I covered the cooler with a blanket and a flannel sheet. This is my first time mashing this high of a temperature however I'm hoping my IPA turns out more malt forward than my last batch. Will post back with results.

I haven't done a lot of this overnight brewing, but that seems like a lot of temp loss, no? One thing I've done when I've needed to leave my wort in the cooler for long periods of time is to wrap the lid tightly with cellophane--that seems to reduce my heat loss pretty substantially. Just a thought for the future.

Cheers

jerrodm said:

I haven't done a lot of this overnight brewing, but that seems like a lot of temp loss, no? One thing I've done when I've needed to leave my wort in the cooler for long periods of time is to wrap the lid tightly with cellophane--that seems to reduce my heat loss pretty substantially. Just a thought for the future.

Cheers

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+1.

I started wrapping my cooler with cling wrap as well and it really helps. As far as temp loss, I think he'll be alright. Most of the conversion happens early before too much heat is lost.

As long as the mash doesn't drop below 140 for too long I believe its pretty safe.

zyx345 said:

Based on the above, I just did a batch mashing in at 158 F at 9:00pm and I took a temperature reading at 12:00pm the next day and I was at 143.7 F. I'm using a Coleman Xtreme cooler and BIAB. I covered the cooler with a blanket and a flannel sheet. This is my first time mashing this high of a temperature however I'm hoping my IPA turns out more malt forward than my last batch. Will post back with results.

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Please do report back. I've started to get this tuned-in pretty well. Record your OG and FG please, as well. I find that 158 is the more malty side, preferrable for Oktoberfest, stouts, etc. I might even try 160 if you want super malty. Even 156 turns out fairly dry. My Helles lager I mashed at 154 I believe and it's nice and dry, but not uber dry like my 153 pale ale with US-05. The lager yeast doesn't attenuate quite as much, though.

Did this last weekend, twice, with two batches of my Lager recipe.

Temp started at around 154 or so and dropped to about 146 one night and 144 the other. I think that was over about six hours or so.

Honestly, I think I will be using this technique as a standard. The way my schedule is I can get things done late into the night or early in the morning. Once it gets past 10 AM though I get the hairy eyeball on the weekend.

Will be doing it again this weekend for a Belgian Pale Ale.

Thanks for the tip!

Skarekrough said:

Did this last weekend, twice, with two batches of my Lager recipe.

Temp started at around 154 or so and dropped to about 146 one night and 144 the other. I think that was over about six hours or so.

Honestly, I think I will be using this technique as a standard. The way my schedule is I can get things done late into the night or early in the morning. Once it gets past 10 AM though I get the hairy eyeball on the weekend.

Will be doing it again this weekend for a Belgian Pale Ale.

Thanks for the tip!

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It's served me very well, too. Just keep your eye on attenuation and mouthfeel. 154 should produce a pretty dry beer, so fine for most pales, IPA's, light lagers, etc. but probably not great for malty lagers, stouts, porters, etc.

tre9er said:

Please do report back. I've started to get this tuned-in pretty well. Record your OG and FG please, as well. I find that 158 is the more malty side, preferrable for Oktoberfest, stouts, etc. I might even try 160 if you want super malty. Even 156 turns out fairly dry. My Helles lager I mashed at 154 I believe and it's nice and dry, but not uber dry like my 153 pale ale with US-05. The lager yeast doesn't attenuate quite as much, though.

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I just bottled my batch on 1/6/12. This was Yooper's DFH 60 clone (https://www.homebrewtalk.com/f69/dogfish-head-60-minute-clone-ag-extract-25709/). OG: 1.072 and FG: 1.021 using S04. The high FG was most likely due to fermenting at +/- 60 degrees F.

The hydrometer sample did taste maltier and slighltly sweeter than my prior batches using this method which is what I was going for. I may even try to mash in a little higher at 160F on my next IPA.

Once carbonated I will update this post on the final tasting results.

tre9er said:

It's served me very well, too. Just keep your eye on attenuation and mouthfeel. 154 should produce a pretty dry beer, so fine for most pales, IPA's, light lagers, etc. but probably not great for malty lagers, stouts, porters, etc.

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I never really considered that.

I did a Porter a few weeks ago where I know I was around 156 or so. My efficiency was quite good and fermentation took off like a rocket.

Proof will be in the pudding when I keg it up and serve it.

I did my first overnight mash after reading this thread. It went well, I mashed at 158*. 11 hours later it was at 138*. There were no sour smell and everything seemed pretty good. With that being said, my SG was way over what it was supposed to be. I finished at 1.070. It was supposed to be 1.047. Here's the recipe.

Recipe: Bass Clone
Style: 8A-English Pale Ale-Standard/Ordinary Bitter

Recipe Overview

Wort Volume Before Boil: 8.08 US gals
Wort Volume After Boil: 6.28 US gals
Volume Transferred: 6.28 US gals
Water Added: 0.00 US gals
Volume At Pitching: 6.28 US gals
Final Batch Volume: 5.50 US gals
Expected Pre-Boil Gravity: 1.036 SG
Expected OG: 1.047 SG
Expected FG: 1.012 SG
Expected ABV: 4.6 %
Expected ABW: 3.6 %
Expected IBU (using Tinseth): 37.3
Expected Color: 9.8 SRM
Apparent Attenuation: 72.9 %
Mash Efficiency: 70.0 %
Boil Duration: 80.0 mins
Fermentation Temperature: 64 degF

Fermentables
UK Pale Ale Malt 8lb 0oz (69.3 %) In Mash/Steeped
UK Flaked Corn/Maize 2lb 8oz (21.7 %) In Mash/Steeped
US Caramel 60L Malt 8.00 oz (4.3 %) In Mash/Steeped
Canadian Honey Malt (Gambrinus) 8.00 oz (4.3 %) In Mash/Steeped
UK Roasted Barley 0.75 oz (0.4 %) In Mash/Steeped

Hops
UK Target (9.5 % alpha) 0.75 oz Loose Pellet Hops used 60 Min From End
UK Golding (5.4 % alpha) 0.75 oz Loose Pellet Hops used 30 Min From End
UK Golding (5.4 % alpha) 0.25 oz Loose Pellet Hops used 15 Min From End
UK Golding (5.5 % alpha) 0.25 oz Loose Pellet Hops used At turn off

Other Ingredients

Yeast: Wyeast 1084-Irish Ale

I guess my efficiency was higher than usual. I'll keep you updated.

I have done 4 or 5 overnight mashes now and love the convenience of starting my brew process after the kids are in bed, and finishing by noon the next day.

My observations are that I get higher efficiency (75-80% vs. 70% in a normal 1hr mash) with a batch sparge. I also generally mash-in around 10:00 to 11:00 pm and the mash is usually in the low 140's to high 130's in the morning - usually 8:00am or so. I have never had any sour issues. I will often fill my mash tun to capacity which can create a very thin mash (3+ qt/lb depending on the grain bill). For a smaller beer,I will sometimes do a no-sparge overnight mash. Just did that with a dry stout. 10lbs of grain and around 9 gallons of water. Mashed in at 154, drained in the AM at 141 and started to boil. Got about 65% efficiency from the no-sparge overnight mash. When I have mashed in at higher temps, like 158, I have found that I usually get a FG around 1.020. I think that a mash-in temp at or below 155 is best for an overnight mash for a beer that you want to attenuate down below 1.015. I have done a couple of 1.060 (or so) pale ales with an overnight mash at 155 that finished at 1.012 (or so).

Howdy folks!

I'm waking up this tired, old thread!

For the first time in quite a while I'm doing an overnight mash tomorrow night.

It's this years pumpkin ale. I've decided I'm not a huge fan of the style when it comes to everyday pumpkin ales, so this year I'm kicking things up a notch. I've decided I might enjoy it more if it's much more full bodied and heavy, slightly sweet, and a higher abv than typical. I've decided to mash pretty high, since it's overnight. That should ensure some residual sweetness and keep my mash temp above the critical point for me. I'm hoping the overnight mash will get me a few extra efficiency points, since I'm going high gravity this year. I'm shooting for maybe 8.8-9.5% abv. I might even age this one on some whiskey soaked oak, but I haven't made my mind up on that yet.

Happy brewing friends, and Cheers!

Funny how disastrous brew days make for such splendid names! My recent AG hefe I dubbed "Right-hand Hefeweizen" as I actually submerged my right arm up to the elbow in the mash tun to try and resolve a stuck runoff. Can you say *OUCH!*? good thread though.

RachmaelBenApplebaum said:

Funny how disastrous brew days make for such splendid names! My recent AG hefe I dubbed "Right-hand Hefeweizen" as I actually submerged my right arm up to the elbow in the mash tun to try and resolve a stuck runoff. Can you say *OUCH!*? good thread though.

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Yep, I've been there!

wickman6 said:

Yep, I've been there!

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Yep, me too!

Stauffbier said:

Howdy folks!

I'm waking up this tired, old thread!

For the first time in quite a while I'm doing an overnight mash tomorrow night.

It's this years pumpkin ale. I've decided I'm not a huge fan of the style when it comes to everyday pumpkin ales, so this year I'm kicking things up a notch. I've decided I might enjoy it more if it's much more full bodied and heavy, slightly sweet, and a higher abv than typical. I've decided to mash pretty high, since it's overnight. That should ensure some residual sweetness and keep my mash temp above the critical point for me. I'm hoping the overnight mash will get me a few extra efficiency points, since I'm going high gravity this year. I'm shooting for maybe 8.8-9.5% abv. I might even age this one on some whiskey soaked oak, but I haven't made my mind up on that yet.

Happy brewing friends, and Cheers!

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whatever the recipe mash temp calls for, bump it up at least 3 degrees unless you want a MUCH drier beer, FYI

tre9er said:

whatever the recipe mash temp calls for, bump it up at least 3 degrees unless you want a MUCH drier beer, FYI

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Thanks! I do indeed mash high when I do overnight mashing.

Without some form of temp control and/or mash recirculation, how you prevent the overnight mash from producing a very fermentable wort and hence dry beer? I can't imagine you can keep your mash above 150 for that length of time. I used to brew in insulated coolers and it was common to drop from 150 to 147 over the course of even a couple of hours. I would think you'd be down in the low 140's or upper 130's with a 8+ hour mash.

Not saying you guys haven't figured out how to make this work, just wondering how.

PLOVE said:

Without some form of temp control and/or mash recirculation, how you prevent the overnight mash from producing a very fermentable wort and hence dry beer? I can't imagine you can keep your mash above 150 for that length of time. I used to brew in insulated coolers and it was common to drop from 150 to 147 over the course of even a couple of hours. I would think you'd be down in the low 140's or upper 130's with a 8+ hour mash.

Not saying you guys haven't figured out how to make this work, just wondering how.

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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.

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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I have a particular recipe that I like to dry out, and that's usually on an overnight mash. I haven't brewed it in a while but when I do I don't bump the temp at all on purpose. I get it down to 1.002 to 1.004 with Wyeast 1007.