Mash Hotspots

[bennyc]

Howdy all,

I put down another AG APA yesterday, and some of the process I used reminded me of a question I'd been meaning to ask for a while.

I brew using a four-ring burner, and all the batches that I've done so far have been single step infusions (66-67C) with a mashout of 78C. When it comes time to turn on the stove and raise the temperature to 78C, I find it incredibly difficult to get a good single reading of what the mash temperature is. There seem to be hotspots all over the mash (I'm assuming related to where the flames on the pot are), and even stirring doesn't seem to alleviate the problem (I'm also weary of stirring too much, oxidisation etc). Does anyone else have this problem, and if so, how do you address it? So far I've taken a she'll-be-right close-enough kind of approach, but looking down the track towards some step infusions, I'm wondering what the best plan of attack would be. :huh:

I'm wondering whether mashing-out (and stepping up) with water additions is the way to go, but this presents problems in terms of the size of my lauter tun. I suppose I could I start with a lower L/grist ratio for mash-in, but this then has other consequences.

Thanks for any ideas,

Ben

 

[reviled]

Stir the living shit out of the mash mate, dont worry about oxidising it cos when you boil all the oxygen gets driven off...
When I apply heat to my mash im pretty much stirring constantly the whole time untill I hit my temp, sometimes ill add a few litres of boiling water to get it there quicker...

 

[Bribie G]

On hitting your strike temp why do you need to do anything other than insulate the tun and walk away for a few HBs, come back later and mash out with hot water from your hot liquor tun or stockpot you have had on the stove whatever?

I use a 40L urn, and if I start at 68 I might lose one degree in an hour and a degree and a half in an hour and a half. Probing various spots at the end of the mash reveals a constant temp.

Solution: a cheap chinese duck feather doonah from Woolies:



Edit: It's only a single but I reckon it would handle up to a 60 L pot no problems and I get far better heat insulation than any esky.

 

[rich_lamb]

YES, we all have that problem (though some don't realise it). It's quite difficult to say precisely what your mash temp is, and for how long because it changes quite a bit over the first 5-10 minutes and more slowly after that. So when people give you a single number for a mash temp you take it with a grain of salt.

There's a difference between stirring and splashing. A good stir won't hurt you - stir all over the tun for a few minutes (don't go berserk or anything) and take your best estimate. The key is being consistent with your measurement, and learning to know what the outcome is.

Also common dilemma - water infusions vs. volume tradeoffs. Personally if I'm doing steps I do direct heat in a pot for the lower steps as they are easier to hold, then transfer to the esky for the sacc. rest.

One other tip - I try to avoid mash-out above 75, as I'm paranoid about any possible source of astringency. I don't find I need it that high anyway. I haven't proved this causes astringency, so I may just be quoting dogma here.

 

[BOG]

Well you are in Queensland. Try that in a NSW winter !

I suppose you don't really need a dooner in queensland.


BOG

 

[bennyc]

I use a 40L urn, and if I start at 68 I might lose one degree in an hour and a degree and a half in an hour and a half. Probing various spots at the end of the mash reveals a constant temp.

Maintaining the temperature isn't the problem - I can mash at 66C for an hour and maybe lose half a degree. It's the raising to 78 mashout (and potentially future step-ups that I'm concerned about...

There's a difference between stirring and splashing. A good stir won't hurt you - stir all over the tun for a few minutes (don't go berserk or anything) and take your best estimate. The key is being consistent with your measurement, and learning to know what the outcome is.

Yep, that's what I aim for - stirring without splashing. Glad I'm not the only one with this problem!

One other tip - I try to avoid mash-out above 75, as I'm paranoid about any possible source of astringency. I don't find I need it that high anyway. I haven't proved this causes astringency, so I may just be quoting dogma here.

Yep, I'm pretty paranoid with it too - same with sparging. It can be hard to get the grain bed to a good temperature fly sparging, but with a bit of fiddling I'm getting there!

Thanks for the replies guys,

Ben

 

[Screwtop]

The problem with trying to monitor temps during ramp-up is the same as mash in. You need to allow time for temperature equalisation, you measure the temp at one point but many dynamics are at play, water, grain and tun all absorb heat at different rates and at the same time dissipate heat at different rates into the space adjacent them. The wort is gaining temp from the directly heated tun, but loosing it at the liquid/air interface, the tun is gaining heat from the heat source and loosing it at the tun/adjacent environment interface, be this camping mat insulation or whatever, and so on.

You need time to get to know your system. Heat for 5 min, stir a little and wait 10 min for temps to equalise. I'm in the stirring increases astringency camp, a bit like jiggling your tea bag too long, astringent tea. If the required temp isn't reached heat for another 5 min and do the same again. Once you are totally familiar with your system you should know how long it takes roughly to raise your mash temp X degrees.

You will usually find that the temp in the mash is higher in the liquor above the grist (duhh heat rises) than in the grain bed and there will be spots around the tun giving different readings, leave the mash to equalise temperature. Mount a thermometer somewhere in the tun and use it as your reference point. Allow time for equalisation and use the temp from the tun mounted thermometer as your mash temp.

Cheers

Screwy

 

[bennyc]

Great advice - thanks Screwy!

I hadn't thought about the equalisation aspect. I'll definitely have to experiment with a forgiving APA or three!

:icon_cheers: