Can wet crushing impede mashing?

Last weekend I tried it. I get considerably less broken hulls, practically whole. Kernel was broken all right. So far so good.

I added 0.5 liter of cold water to six kg of malt by pouring it slowly while stirring malt continuously. Waited about half an hour, stirring it once in a while. I milled it with roller mill.

Sadly, mashing to negative iodine test took not one hour, but two. OK, after one hour solution was free of starch, but stirring still released more of it, while it normally does not, at that point. After 2 hours solution was starch-free even after stir, but I heated to mash-out really slowly, just to be sure. Total time - 3 hours instead of a bit over one.

Overall efficiency was unchanged, 90% of theoretical maximum, perfectly consistent with my usual results - but it took over twice the time. Can there be causation along with correlation, or can I assume it was just a coincidence?

Topic crush all-grain mash homebrew

Category Mac

1
answered at

Brewing textbooks I referred to universally state that the gap between the rollers of the mill needs to be much closer together for wet-milling. You don't mention making any adjustments, so I'll assume you didn't. Since the husk is made more elastic by conditioning, the dangers of pulverizing it with too tight a mill are eliminated, and in fact it may do a better job breaking down the endosperm, which also may have become less friable during conditioning.

This would fit with your experience of a very slow conversion and starch going into solution when the mash is stirred, which could be explained by (counter-intuitively) too large a grind. Or put another way, while wet milling helps the husk hold together, it may also help the starchy parts stick together too, creating a potential issue of over-large endosperm bits which don't easily gelatinize or solubilize.

A few quotes, as mentioned above:

"During [wet] milling they are gently squeezed flat by the large rolls (400mm, 15.75in. diameter; 440rpm, gap 0.30±0.45mm, approx. 0.012± 0.018 in.) of the mill, squeezing out some of their contents." (source)

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"[In wet-milling, t]he rollers are closer together than in dry milling (0.35 – 0.45 mm apart)" (source)

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"The gap between [the rollers], which may vary from 0.25 and 0.40mm, can be continuously adjusted." (source)

For reference, the same books give ranges between 0.6 and 1.5mm for gap spacing in two-roller mills used with dry malt.

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