Mash Temperature Variations

[Rubes]

I mash in a 15L round esky and do batch sparges. I used to think that it held the temperature pretty well over an hour or so. I have a digital temperature probe that I just stuck in the middle of the mash. Once the temperature was right I just wrapped the whole lot in an old fleece and left it alone while I polished off a few brews. I was a happy brewer.

But....the other day I happened to bump the probe and it dropped down to the bottom of the mash. No dramas I though until I saw the temperature. Now it was nearly 7oC lower. I did a bit of experimenting and took some readings from the top, middle and bottom. All different and by enough of a spread to radically alter the mash profile. Now I am thinking what sort of mash am I actually doing here? Is it going to be dry, malty or a bit of both?

I guess that the middle of the mash is the best place to take a reading and that I should have been mixing up the mash more to even the temperature but does anyone have any words of experience?

 

[jayse]

first point is the temp is fine it is actaully the PH that is most important and without a way to measure that the only way to tell is by the attenuation.
same as for the mash temp the best way to tell is by the attenuation.
to much attenuation then it was to low not emough attenuation and the temp was was to high.

thats a simple way to look at it.

anyway i would be constantly mixing it around in your case.
i like sitting and watching my mash and i do mix up quite a few times during the 90 mins of mashing.

simply tell by the finished beer how you think the mash went and yes keep giving it a mix up.
common sense may tell you mixing it up a fair bit will give you a few points extra in effiency also.

does that help?

jayse

 

[wedge]

i find the problem is the only way to check is to take the lid off the esky, hence loosing heat and then i'm always chasing the temperature, one minute too hot, one too cold. I find though with my digital thermometer whe the whole probe( handle wire) is submerged it reads too high. Though when only the metal part is submerged it reads about right.

 

[RegBadgery]

I find that a really good pre-heat and then a really good mixing helps a lot. I bung some hot water in my rubbermaid for a wee while before doing the mash.

After adding and mixing the malt I take a look at the temperature from several different areas of the mash, then let it sit for 10 minutes or so - have another look and a bit of a temp. read, let it sit again till about half way throug the mash - then have another look.

My technique isn't sufficiently precise - I aim for a reasonably stiff mash at the outset, so that additions of hot or cold water won't thin it out too much.

I've mashed on the stove using a pot (periodically stirring the contents) - worked well, thought the stove I had at the time was a bit crook - not much chop in the heat adjustment area.

Down the track I might look at a direct-heat mash via a gas burner. I imagine I'd get pretty good heat-source control - though I suppose I'd have to keep stirring to avoid overheating the grain at the bottom of the mash vessel??

cheers
reg

 

[sosman]

I find the esky doesn't lose much heat, it is the old "variation throughout the grain bed" that gets me every time (all two of them).