Every time I seed a gunny sack of sunflower seed kernels in a supermarket, I wonder how they are extracted from their seeds. It is very difficult to extract even one of them by hand without smashing its kernels, I really wonder the process that extracts mass of them.
How do they do it? Is there a documentary or Youtube video about it?
By using a dehuller machine. See: http://www.youtube.com/watch?v=-hegzzj9Rzk or http://www.buhlergroup.com/global/en/products/dehuller-dgba.htm
How does a dehuller work? I don't know, but it seems that Google does:
The most popular decorticator for sunflower is proposed by the Bühler Cie. It consists in a rotating blade that propels the seeds by centrifuge force against a wall. It functions on one impact. It is designed for partial removal of hulls because due to its principle, it is not able to carry out a good dehulling without increasing the force of the impact. The kernel oil content is so high in sunflower that under the violence of he chock, some oil can be transferred to the hulls and is lost. Moreover, increasing the rotating speed of such dehuller drives to increase the production of fines that are difficult to separates from hulls. Another mono-chock kind of dehuller is air-jet impact where the propelling of the seeds is done by a strong current of air. Multi-chocks dehullers like the Ripple mill improve the dehulling quality because they carry out several impacts on the achene with milder violence and enable en enhanced separation of hulls without generating an excess of fines.
See: http://www.creol.fr/CTMSite/creol/us/travaux/img/dehulling_3.pdf
See also: http://www.buhlergroup.com/northamerica/downloads/DGBA_Sunflower_Dehuller.pdf for some schematics of the inside of the machine and some insights about the way it works.
Just to visualize a bit Raco's answer. There is a scheme of the Buhler machine provided by Buhler Group.
In the brochure from here (but not well explained).
Also, oilseed processing machine looks similar: https://www.buhlergroup.com/content/buhlergroup/global/en/industries/Oilseed.html
This is not an answer actually, just a few more links to investigate the topic.
