Adventures in barley dehulling

I set about testing the dehulling plates for our Grainmaker No 99 flour mill using some barley from my 2017 grain trials.

The mill looks like this:

Pictured below are the Grainmaker steel plates (on the left) used to grind grains for flour. The rubberized orange plates (on the right) dehull grains by removing their outer hulls.

The plates with the large hole (bottom plates) go closest to the feed hopper and are stationary. I'll refer to them as the inner plates  The plates with the small holes (top plates) go in the outer position and are rotated by the crank.

Grainmaker's instructions are very clear about not trying to dehull buckwheat grains because their triangular shape will damage the rubber plate coating. They also say the mill won't dehull sunflowers.  Well, luckily for me, I want to start with barley.  I also saved some spring wheat that was more difficult to thresh cleanly by hand to try.  John Sherck of Sherck Seeds has offered some einkorn and rice and I look forward to trying these in the future.

Starting the process with an inner/outer plate configuration of steel/rubber, I tested three levels of tightness.  I used samples of my Full Pint barley which contained the seeds threshed from my bucket of "eat" grade grains, which is a polite way of reminding myself that these heads did not have the uniformity for replanting.  To add a bit of a challenge, my first test consists of seeds of all sizes, which should prove interesting.

The kernels trapped between the steel and rubber plates are visible.

In this first run, regretfully, in addition to the barley, I did have a handful of wheat berries that were unnoticed in the mill that therefore were also processed. I attempted to pick out all traces of the wheat. 

 

First run, least tight setting tested:

 

.... little more tight gives:

 

... and the tightest setting yields this:

 

A typical example of the screened fines and broken bits look like this:

While the gleaned and cleaned desired grains (with a few wheat kernels removed) look like this:

 

With a bit of counting and calculating, I found the following:

24% dehulled in the first pass at the lowest setting tested

38% dehulled in the first pass at the middle setting tested

51% dehulled in the first pass of the tightest setting tested

I can increase the tightness setting; however, I was concerned with breaking too many grains.  

So after this first attempt using the Grainmaker to dehull barley, here are my initial observations and future plans:

• The adjustment screw is fine enough to have a measurable effect on the outcome (% dehulled in that pass thru the machine). 
• The space around the feed auger is large enough, that 'tablespoon sized' experiments can not be run back through to test a 2nd pass as it could not grab the few kernel and pull them to the plates.  So, larger samples should be used.
• With larger samples, percent by weight would be easier than counting seeds.
• Since it was difficult to know how many bits and pieces made up the broken seeds, I did not include them in my counts.  Using weight, I will sort into freed seeds, hulled seeds, broken seeds and chaff.
• The 'tightness' adjustment knob has 'clicks' to provide defined position.  I will count how many 'clicks' open from a 'zero visible gap'.  This will provide a repeatable system to allow quick setup and trading of information.
• Next time, screen out the underfilled seeds before processing as a treat for the chickens.  Also, screen out the largest of the seeds for possible planting.