Meditations on malt conditioning before milling

[lupulus]

[Bilsch]

Another important parameter is mill speed. I've run my same mm3 at ~350, 180 and now 65 rpm and the results are quite different at each speed. (Gap 0.048") I suspect the faster its run, the more mismatch in individual roll speeds causing irregular tearing. In this configuration the grain seems to be predominantly broken in half across the lateral axis, husk as well. Then the halves get broken in another 2 to 3 pieces through the second roll. The husks aren't greatly changed through the second roll. There isn't but a whisp of flour and as was mentioned the efficiency is lower, in the high 70's, low 80's. However the grain wets like a dream and carries with it so few entrained bubbles that stirring is not necessary. I hang the mashcap slightly above the grain and it floats during the underlet and doesn't get touched again until the wort is transferred to the bk.
I'm firmly in the no conditioning camp.

[mchrispen]

Ric,

I have seen similar issues with the Brew-Magic. The higher (1-2% water/weight) water ratio drops my extract efficiency significantly. At 1%, I lose just a few points. I recently did some congress mashes with different water/weight ratios and was shocked to see the poor extract. Just not sure what is going on - except that the pliability of the husk and pericarp seem to leave larger bits, and the flour seems to stick to the husk material. I did run some sieves to compare a while back and both crushes were really good. Since the BM requires circulation the full time, I have to carefully monitor circulation, which I start after about a 10 minute still rest to allow the malt to hydrate (similar to your procedure). After that ten minutes, I slowly ramp the circulation speed till it's "half" open (1/4" SS lines) and I can maintain 2-3 inches above the mash bed.

I get far fewer bubbles and foam with conditioned grist, but fully underletting slowly at grain in gives me nearly the same result. I wonder if part of the issue you are seeing is the shape of the bag bottom - and the basket with side perforations? That may be simply causing a minor hydraulic issue where the pressure gradient falls off more quickly the taller the mash bed?

My MM-3 Pro is direct driven - at 180 RPM - so speed is consistent. Currently set at 0.04" - and I plan to leave it there for the time being. I'm tired of chasing mash efficiency - so this will just land where it will.

We can run some trials with my mill if you want to isolate yours.

[lupulus]

Thanks Matt!
My key question was whether there was any evidence that the conditioning method we have been using (1-2% w/w 5-15 min before milling, and immediate dough-in) is better than dry milling (and immediate dough-in) from a low-oxygen perspective.
From the answers, my conclusion is that at best there may be some theoretical but unproven benefits.
It seems clear that other mills, because roll design, diameter, rotation speed, or having an additional roll, can mill grains in a way that provides advantages.
However, for me, I do not see a difference in efficiency, beer is good either way, and if I do not condition, I do not need to monitor the recirculation flow to check whether I am creating a vacuum. The only problem is that with non-conditioning it stops driving a few times, so I need to put the malt back in the bucket and reload, but no big deal, just a minute or two.
Thanks for the offer though

[Weizenberg]

If the filter bed starts to clog up, then chances are that the flow rate is too high.

Any gain bed will compact excessively under those circumstances.

For inert mashing, milling under water (MEBA hydro mill) is probably best but only makes sense where large charges are being processed. The volumes we process don't cause the malt to hang around for a long time, so potential damage is limited.

Narziss has a very good chapter on milling in Abriss. IIRC He even published tables of data collected using various milling methods. Didn't he mention any of this in your copy? I found his reworked chapter on milling in the latest edition rather excellent.

[Techbrau]

Here's some more details about my system if it's a helpful point of reference:

Mill is a MM2-pro with the gap set to 0.026". I spin it around 60 rpm.

I only condition the malt immediately before I mill it

I start with 24 liters of degassed water + 3.6 kg of malt and end up with a preboil gravity around 11.2-11.4 Plato.

My recirculation speed is about 3-4 liters per minute. I use the morebeer heavy duty 8 gallon kettle as my mash tun along with their false bottom. The recirculation inlet draws from a dip tube under the false bottom at the center of the kettle and the outlet is just straight in the sidewall of the kettle an inch or two above the grain bed.

I acidity my strike water with about 750-800 ml of sauergut before I dough in. Mash pH is around 5.3.

I dough in at 64-65c for a 30 minute beta rest, which I generally allow to drop to 63-64c over the course of the rest. I then raise to 72c for a 30 minute alpha rest followed by a 5 minute mashout at 76c. I undershoot my gravity by about 0.5 Plato if I don't do the mashout.

I've tried recirculating only during temperature steps, for a few minutes intermittently during the rests, and continuously through the entire mash. Conversion is a bit slower if I only recirculate during steps and not during the rests, so I usually try to recirculate for a little bit here and there during the rests. Conversion is ridiculously fast if I recirculate continuously (I generally hit 8-9 Plato within the first 15 minutes at beta when I do that).

I'm using 20 mg/l SMB + 20 mg/l AA + 30 mg/l BB.

[lupulus]

[lupulus]