[dougcogley]

Today I was doing a normal all Grain brewing day and I missed my mash out temp of 168 - 170 degrees, so I added the mash tun onto a burner to raise the temperature.  While doing this I went to grab my spoon to stir the mash and the thermometer read  178 degrees.  I immediately pulled this off the burn and removed the lid, but it was to late.....  I finished the brew day and when I took my OG. It was 12 points off.  I got 1.060 instead of 1.072.  I fly sparge and consistently get 75% efficiency.  Today I got 59%. Could the high mash out temperature have made me miss my the target OG?

[tschmidlin]

Not likely, assuming your mash was otherwise normal.  I would look to something else as the cause.  Was the grind the same?  Were you mashing higher than you thought?  How long did it take you to find your spoon?

[dougcogley]

Well this is the first kit I purchased from Austin Brewing "corsendonk brown" so I am not sure if the grind was different or not.  My mash tun is using a new blichmann thermometer that is accurate with others that I have.  I aways check it before brew.   I mashed At 150 degrees for 1 hour.  My burner was outside and I just stepped into the kitchen for a minute or so... not long.  Hmmm now I am really stumped as to the root of this issue.  Do you have any other ideas?

[tschmidlin]

It sounds to me like the thermometer was not reading the proper mash temp.  If the thermometer is accurate, then the mash probably wasn't mixed sufficiently.  Unless you have some kind of crazy jet engine burner, the mash temp isn't going to jump from somewhere below 168F to 178F in the minute or so it took you to go get your spoon.

So it could have been reading low when you left to get your spoon, or high when you got back, or low the whole time, or something else.  It's hard to say.

[tomsawyer]

I'd say it was the crush if your thermo checked out with the others.

[euge]

Not only the crush but was the grain weight checked?

[tschmidlin]

Yeah it could definitely be either of those things.  But with the known temperature measurements, what about the temp going from a missed mash temp between 168-170. so somewhere below that, to 178 in "a minute or so".  Have you ever had anything like that happen when the mash is well mixed?  It sounds more like hot spots to me.

[dzlater]

I am not sure about this, but if conversion wasn't complete for whatever reason, and you did the mash out
which stops the enzymes. That might account for the low efficiency?

[tomsawyer]

Mashout isn't instantaneous, it takes around fifteen minutes to denature enzymes.  If you were "mashing out" the whole time instead of just at the end I think you'd ge a really low efficiency AND the wort wouldn't attenuate worth crap.  Tom, I see what you mean in that the thermo is a new item.  I've heard more instances of a coarse crush leading to 60% efficiency than a bad thermometer.

[tschmidlin]

You're right, a coarsely ground malt is definitely a possibility, but we have no info either way on that.  But there can be multiple things going on and the jump in temp indicates to me that there was an issue getting proper measurements as well.  If it is a temp issue I'm thinking more that it isn't mixed well rather than just off a couple of degrees - more user error rather than a problem with the thermometer itself.