# Gladfield malt mill gap



## SMOKEU (15/5/20)

I had a really bad experience with getting a terrible brewhouse efficiency of only 36% with a hefeweizen recipe using 59% Gladfield wheat, and the rest was Gladfield pilsner malt and a little acid malt.

Gladfield recommends a mill gap of 1.45mm which seems very high. The brew shop who milled the grains for me said he sets his grain mill to 1.45 as per Gladfield's suggestion but the grain doesn't look especially well crushed.

I usually get a brewhouse efficiency of around 70% using my Robobrew.

This is from Gladfield Mill gap

What mill gap do you normally use for Gladfield malts in general, and especially for Gladfield wheat?


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## huez (16/5/20)

Your problem was probably the high percentage of wheat. Your mash likely got stuck and the wort flowed around the outside rather than through it during the mash and when lautering. Throw in some rice hills next time, or seeing that you are from NZ gladfield sell oat hulls.


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## SMOKEU (16/5/20)

huez said:


> Your problem was probably the high percentage of wheat. Your mash likely got stuck and the wort flowed around the outside rather than through it during the mash and when lautering. Throw in some rice hills next time, or seeing that you are from NZ gladfield sell oat hulls.



I don't think it got stuck, I added 500g of oat hulls and the wort was flowing through the grain bed much faster than I've ever seen with this Robobrew.


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## MHB (16/5/20)

Good to see a maltster paying some attention to the mill gap, its one of those really important steps on the journey from malt to good beer that usually slides under the radar.
Screening on a 2.5mm screen post malting and claiming an average plumpness of 2.8mm is exceptional, that's actually quite a lot bigger than most malts except perhaps some of the UK ones.
Worth noting that the information is only for Barley malt and wheat needs very different handling.
I would in a high wheat malt grist normally crack the wheat and barley fractions separately. 
Crack the wheat at least twice often three times, first pass at 1.8-2.0mm, second pass around 1.4-1.5mm, then likely another pass at around 1.0mm. Then mix the wheat and barley and crack the mix, would agree that around 1.4mm would be good for the barley.
Wheat lacks a husk, is a different shape and is a lot harder than Barley malt, the aim of cracking wheat is to get a fine kibble and very little flour. With care you can get an almost dust free kibble that allows fast extraction, very good flows and little chance of a stuck sparge, all without needing "hulls" of any sort.
Without careful treatment, I find people get much lower efficiencies slow and stuck sparges...

Rye and Oat malt are other grains that need special attention. Treat rye like wheat, just a lot finer, miss the first pass and finish it at 0.6-0.8mm. Oat malt I tend to run first and on its own at about 0.25mm, just smash it as its got a huge husk fraction and doesn't crack as much as just spread out.

I have a little sift set with 2.0mm, 1.0mm, 0.5mm screens and have done a fair amount of work on grind optimisation.
Trying different settings and shaking down a sample, weighing fractions... all very tedious but if you think of a 10% improvement as giving you every 10th grain bill for free it really counts when brewing commercially.
There is an set of EBC standards for malt sifts and they are different to what I have, but sometimes you just have to use what you have, and yes it makes a bigdifference.

Depending on how much work your LHBS is willing to do on your behalf, making a lot of wheat beer might be the best argument for investing in a mill that I can think of. If you plan on doing a lot of wheat beers make sure you choose a mill that is easily adjustable.
Mark


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## Sidney Harbour-Bridge (16/5/20)

MHB said:


> Good to see a maltster paying some attention to the mill gap, its one of those really important steps on the journey from malt to good beer that usually slides under the radar.
> Screening on a 2.5mm screen post malting and claiming an average plumpness of 2.8mm is exceptional, that's actually quite a lot bigger than most malts except perhaps some of the UK ones.
> Worth noting that the information is only for Barley malt and wheat needs very different handling.
> I would in a high wheat malt grist normally crack the wheat and barley fractions separately.
> ...


Thanks Mark.

How would conditioning with water affect the mill process?

I let my barley malt sit for 20 minutes with about 1.5 % of it's weight of water added, my mill is set at .050" or 1.25 mm, I run wheat malt through separately at the same setting, mainly to dry the rollers, I get good efficiencies with this method, 85% and above.


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## MHB (16/5/20)

Lacking a husk it wont help the wheat at all, how much it helps the barley is going to depend on lots of variables but on balance there aren't any downsides to malt conditioning unless you don't use the malt immediately, then it can promote the growth of all sorts of nasties.

Try double cracking the wheat and see if it helps, if the first pass is too fine wheat sort of explodes giving lots of fines that can be a problem.
Cant comment on your efficiency 85% might be good or bad, last commercial brew I did got 84% in the fermenter (Brewhouse Yield) and cant see that getting much better on our system. If that's mash efficiency its not too bad but could easily be 10% better, meh, if it works for you and the beer tastes good you could live with it pretty easily.
Pursuing efficiency at all costs isn't a good idea at some point the beer starts to suffer, good indiction you have gone too far.
Mark


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## SMOKEU (16/5/20)

I tried mashing again after getting fresh grains, and this time they were double milled with extra acid malt (3.8% of the grainbill) and for some reason the mash looked "wrong". It's hard to explain but the wort was flowing extremely quickly through the grain bed and after a 10 minute ferrulic acid rest + 15 minute saccharification rest the pH was 6.3! I threw the grains and wort out as they were of no use.

I just a pale ale afterward with pre-milled grains from a kit and hit mash pH and gravity with no problems, so I don't think it's my equipment or method.


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## MHB (16/5/20)

I'm having a bit of difficulty understanding exactly what has happened,
Worth noting that most Acid malt is calibrated to lower the pH by 0.1pH/1% grist. Not recommended to use more than 5% of grist.
Personally I'm far from convinced that a Ferrulic acid rest is much use, the peak activity for Furrulic (well the enzyme) is around 5.7pH and 38-40oC and its woefully slow. Prefer Bubblegum and Banana anyway.
Double milling wont make the pH go up, it might make for a more permeable bed - but that's not all bad.
Mark


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