Recovering from mash overtemp?

So, I was mashing in for a BIAB with a target mash temp of 153 F. After breaking up all the dough balls, temp check showed I was only at 151 F, so I turned the heat back on. Well, the mash heated up much faster than I expected, and I ended up somewhere between 162 to 165 F (dangerously close to mash out temp). Tried to lower the temp by stirring, but temp was not dropping fast, so I added about 0.5 gal of ~70 F water. That brought the temp down to 152 F (this was about 18 minutes into the mash.) I then covered and insulated the kettle to wait out the rest of the mash. Not much else I could do to fix this mess.

Question for future reference: If you severely overshoot the mash temp to the point where you might degrade most of the alpha-amylase enzyme, is it possible to mitigate the damage by getting the temp back down and adding additional alpha-amylase?

Mash is still underway, so don't know anything about starting gravities yet.

Time to RDWHAHB for now.

Yea, get the temp back down any way you can, cold water, ice, mixing, do what ya gotta do, you have about 15 minutes for minor infractions to be fixed. Their are not many direct fired MLT's. That's why these guys are blabbing about RMS HERMS. Once you mash in it's super easy to overheat the bottom of the pot.

I'd keep going but my guess is that you pretty well denatured all your enzymes.
Finish your mash & check your conversion w/ iodine. Also check your pre- boil SG.
If all is ok, do your boil & good luck.


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Yes. Add amylase and beano. Next time wait to up the heat. I have found once I put the lid on the temp rises point or two.


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doug293cz said:

So, I was mashing in for a BIAB with a target mash temp of 153 F. After breaking up all the dough balls, temp check showed I was only at 151 F, so I turned the heat back on. Well, the mash heated up much faster than I expected, and I ended up somewhere between 162 to 165 F (dangerously close to mash out temp). Tried to lower the temp by stirring, but temp was not dropping fast, so I added about 0.5 gal of ~70 F water. That brought the temp down to 152 F (this was about 18 minutes into the mash.) I then covered and insulated the kettle to wait out the rest of the mash. Not much else I could do to fix this mess.

Question for future reference: If you severely overshoot the mash temp to the point where you might degrade most of the alpha-amylase enzyme, is it possible to mitigate the damage by getting the temp back down and adding additional alpha-amylase?

Mash is still underway, so don't know anything about starting gravities yet.

Time to RDWHAHB for now.

Click to expand...

If your grains were milled fine, your conversion was over before you ever started to add heat. Check your gravity before you do anything else. If your gravity is right, start your boil.

RM-MN said:

If your grains were milled fine, your conversion was over before you ever started to add heat. Check your gravity before you do anything else. If your gravity is right, start your boil.

Click to expand...

Looks like you might be right. I set my Barley Mill gap at 0.016" to get a finer grind than my last batch where I used 0.025".

Did full volume, no sparge mash of 8.5 gal (after 0.5 gal added cool water) with a 10.75 lb grain bill. Beersmith predicted a post boil gravity of 1.051 for 6.0 gal of finished wort (assumed total efficiency of 72%). I got 7.2 gal pre-boil at 1.044, and 6.5 gal post-boil at 1.053.

On to the fermenter.

Brew on

I had the same thing happen, about a year ago, only in a more drastic way. The mash was resting at the high temp end of the proteolytic range. I fired the mash tun on low to bump up the temp into the high temp range of beta. Then, the phone rang. I left the brew room to deal with the call. My brain was locked into the call. It was after being on the phone for about 40 minutes, that I caught the scent of cooking mash. The mash in the area of the center of the tun was boiling. I stirred the mash and the temp evened out at 167. There was 32 lbs of Weyermann floor malt in the tun. I decided not to dump the mash. I didn't bother checking for conversion, the mash was sticky. I didn't mash out, just transfered the mash to the lautertun and ran it off. The process started out as a tri-decoction. Mash pH was low enough to safely boil. The 1st decoction was already completed. I figured that the beer wouldn't be stable enough to endure the lagering stage. The wort was fermented with Budvar yeast at ale temps. After 2 weeks in the primary and 2 in the secondary, I cooled and filtered the beer, added speise and kegged. Four weeks later it was ready and not bad tasting. At 8 weeks the beer was thin and had a slight taste of yeast, hops diminished. After that it was mixed with San Pellegrino lemon soda 50/50, strange taste but in a good way. The end volume was 15 gallons, it took a lot of soda.

In my case, I haven't any idea how long the time frame was from the time the flame was turned on until the point of thermal denaturing of beta and alpha. Except, that it was somewhere within 40 minutes. It appears that enzymes did some converting. The mash was very thick. Much thicker than a bag mash.

Wobdee is experimenting with an interesting process called the Schmitz method. It is a method that baggers can use. It's a type of decoction method where the entire volume of mash is boiled. The interesting twist to the process is the way enzymes are preserved for use later on in the process. Sooner or later I will scale down. If Wob's process works well with the baggery method and produces a beer close to one produced by a tri-decoction. I will break with tradition and sell the 30 gallon, five kettle, gas fired, tri-decoction system that I have now. Then, do a Shingo, leaning out by using the Schmitz process and the baggery method.