Oat groats

The hull is highly indigestible, so it must be removed to obtain maximum nutritional benefits. Oats have a hull that consists mainly of cellulose, Hemicelluloses and lignin. Within the hull is the groat, which comprises 68–72% of the kernel.

Oat groats are cleaned oat kernels that have had their inedible hull removed and take the longest to cook.

The groats have a smoother texture and higher density than unhulled oats, so they move more quickly through the separator.

The groats are then cut by feeding them into a cylinder with a large number of holes, the kernel fall through these holes and are cut to produce what is called Pinhead oatmeal.

Type of groats
*Steel cut groats are groats that have been cut into 2–3 pieces with a sharp metal blade. They are often referred to as Irish oatmeal and cook faster than whole oat groats.
*Steamed rolled oat groats are produced by applying steam to whole oat groats while being rolled into flakes.
*Ground steamed groats are rolled oat groats that have been ground to a meal form.

The outer layer of the groat is an important source of protein, neutral lipids, β-glucan, phenolics and niacin, and is sometimes separated from the groat to produce oat bran.
Oat groats

Cereal processing: Dehulling of oats

The grain is then sorted by size into small grains, medium sized and large size grains. Three basic mechanical methods for dehulling oats include the impact dehuller, the compressed air dehuller, and the wringer dehuller.

Traditional oats mills used stones set at well-defined distances to split the hulls and enable them to be detached from the groats. Although this procedure is still used in some smaller mills, the larger mils that are needed to produce the quantities of oat products required today use impact hullers.

The impact dehuller feeds grain into a spinning rotor. The impact of the grain with a wall as they are expelled from the rotor releases the groats from the hulls. The hulls are then removed by aspiration. The compressed-air dehuller.

The groats is then subject to a polishing which removes the dust and hull which has not been properly dislodged.

The oat hull is mainly fiber; hemicellulose, cellulose and lignin. There are low levels of protein, fat, starch and water-soluble carbohydrates.

Hulls are by products of oat milling, and from this furfural is prepared which, with its derivatives, is used in making nylon, in oil refining and in some other industrial processes.
Cereal processing: Dehulling of oats