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Mash temp too high

Mashing questions for the all grain brain trust - I’m BIAB and was aiming to keep the MASH temp between 154-158. I had turned the burner on once it got around 150. I then didn’t pay as much attention as I should have and the temp shot up to 170 and I got it back down to 160 in 15 min or so. I’m letting it MASH for an extra 15 minutes to try and get more time at the right temp.

My questions -

  1. Did I kill off the grain’s ability to make fermentable sugar?
  2. would adding DME during the boil help trouble shoot this?

Chances are you denatured most of the enzymes, which could result in lower your conversion. Will you need to add DME? Depends on your conversion. How long was your mash in the ideal temps before it skyrocketed to 170°? Luckily most malts now are extremely modified and conversion can happen pretty quickly.


I’m kinda late… did you do a gravity test?
Thought I heard most conversion does happen in the first 15-30 minutes…. Loopie is the info guy….

It spent probably about 30 minutes between 154-158 before I shot it up to 170. I decided to let it sit an extra 15 minutes once it was back down to the desired temp. I did end up adding in DME at the end fo the boil just in case.

Gravity was….?
EDIT: before you went to boil… it’s been a ritual for me to track gravity along the way, right after I mash, and as I boil…

I would imagine that most conversion had happened within that 30mins. Did you take a gravity reading to determine if you needed to add DME? How did it compare to the suggested OG?

By now you likely know what your gravity is going into fermentation via a float hydrometer reading and have the answer to your question.

A refractometer would allow you to measure the gravity of the hot wort with only a couple drops of wort, which does not need to be cooled. This allows you know when the mash is done, whether you need to add DME or water to hit the OG target etc. If you sparge your grist, it also allows you to determine when to stop sparging. It only takes at the most 30 seconds to know what your gravity is at any stage prior to fermentation.

I really should have taken a reading at that point in the mash. I didn’t take one until right before I put it in the carboy. It’s pretty off. OG 1.120 and the recipe was targeting 1.025. I don’t think I started with enough water volume given the grain bill.

A refractometer is a good idea - I don’t have one but Christmas is coming!

A long time ago I read that “everything that happens, happens in the first 15 min.” So I agree with these guys that you may be alright.

A simple and old fashion method to check for conversion is to get a bottle of iodine from the drug store. Put a few drops of wort from the top of your mash on a white plate. Try to just get liquid. Let it cool a little and drip a drop of iodine on it. If it stays brown it converted. If it turns black it did not. Hulls will turn back so that is why you want just liquid.

I don’t usually bother with the iodine test anymore because todays highly modified malts pretty much always convert unless you had a huge disaster. I don’t think yours was a huge disaster but please let us know how it turns out.

Well you got conversion but some of the sugar will be non fermentable maybe because of the high temperature. Reading thee OG gravity isnt the problem. That may be a constant between about 140-170. What will change is the FG. Run it through a mash calculation with the heating profile and you will see the FG will be higher because of the warm temperature. So adding DME or corn will lower the FG it won’t do anything about the un fermentable sugars. The beer is fine to late make adjustments so I’d just leave it alone

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THAT is a huge difference in gravities!! Wow…
Now if you have yeast to tackle that brew… that’ll be the next dilemma…

Wait the recipe was for 1.025? You got 1.125? Something doesn’t add up. How much sugar did you add?

I know I know. I think perhaps the water volume is the culprit. I added about 1/2 a cup of DME. It’s always helpful to learn on this forum. I was going to transfer to a secondary in a couple of weeks so I guess I can take another reading then.

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you better post the recipe .025 will give you about 3% ABV 1.125 will be about 13% ABV

The half a cup of DME in a 5 gallon batch would have negligible impact on gravity. As brewcat says, post the recipe and make sure of your gravity measurement now and if necessary take another sample now and measure it. Reading the hydrometer is tricky and even now I sometimes screw up and get decimal place wrong (frequency of my errors correlates with my beer consumption) :slight_smile:

If you post recipe, target gravity, gravity before fermentation and how many gallons you have in fermenter now we can calculate how much water to add or sanitized DME solution to add to get you where you want to be or whether to do nothing.

So… if volume may be a culprit as well, have you verified the graduations on yer brew vessel? This all becomes a part of “fine tooning” your system… helps you get a desired gravity… in fact, then the hydrometer/refractometer re-assures you of your talents! (:slightly_smiling_face:

So I typically take a 5 gal recipe and divide it in half. Below was the recipe I used.

BIAB: 3.5 gal start vol (in retrospect, this was too low - especially since I boiled some of the first runnings)
MO: 6.25 LBs
Crystal 60: 1.25 LBs
Special B: .25 oz
White Labs Edinborough yeast
East Kent holdings hops

End vol: 1.5 gal

Just using your weights and volume I end up with 1.088… so you may need to look at your hydrometer… and volumes IF you want to get fairly accurate… but just being a hobby, it may not be so important.
EDIT: I bet it’ll still be… BEER!!! :beers:

Well likely not a total disaster! This is just a hobby and I mostly make tasty beer (on the higher abv end) but I do want to be more accurate. How would I verify the graduations for my brew pot. I just got the pot earlier this year (after a few years of using large stock pots).

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