The purpose of dehulling is to remove the husk and possibly the outer layers of the grain or seeds with minimum damage to the bran layer and as far as possible not to break the grains.
Due to surface characteristics of different types of grains it is necessary to apply friction to the grain to remove the husk.It is possible to dehull by peeling, with knives, impact dehulling or with the help of other technologies using heat, water, chemicals, etc.
Dehulling process requires its own infrastructure. Separate bins or storage units are needed for the hulled and dehulled grains. The hulls need to be either stored or transported for their ultimate use, even if they are not being marketed. Dehulling creates dust that needs to be removed to avoid safety and health hazards.
Three basic mechanical methods for dehulling oats include
*The impact dehuller
*The compressed-air dehuller
*The wringer dehuller
Impact dehulling involves feeding oat grain into the center of a spinning rotor that expels the grain against the walls of the dehuller. The force of the impact breaks the hull from the groat.
The compressed-air dehuller uses a stream of pressurized air to apply mechanical shock to the oat releasing the groats from the hulls. In wringer type dehullers, oat kernels are fed individually by hand into a mechanized roller that pulls in the hulls and deposits the groat in a bin.
Dehulling of oats
