Botanically the cereals grain is called carypse and it is composed of three sections, i.e. raw sprouts, endosperm and the bran.
- Raw sprouts:
It is the most important part of the plant, because it is the origin of the new plant. It consists of the following parts:
- a) Radicle (radicula)
- b) The place of buds or leaves (plumula)
- c) Germ cotyledon (cotyledon scutellum)
- d) Cylindrical epthil (cylindecepithel)
When the seed begins to germinate, the roots will appear and the form of chemical materials of the seed will change. The germ cotyledon breaks down the starch during germination and supplies the food required for the grain. Cylindrical epthil is also formed from long cells which deliver food to the endosperm.
The endosperm is composed of different parts, including starch cells, adhesive material cells, such as gluten, and Aleurone layer. The endosperm covers the seed length and makes up about 80- 82.5 % of the seed. The starch in the endosperm is stored orderly in different forms in grains, for example, the starch in the endosperm of the wheat is oval and more spherical.
The thickness of the endosperm cells wall plays an important role in quality and the value of the bakery wheat. Aleurone layer is the outermost cells of the endosperm which surrounds the endosperm cells like a pod. When grinding, Aleurone layer is separated from the flour like bran and the flour crust (particularly the bright flour). Its protein reduces the value of the bakery flour. Aleurone layer constitutes about 7% of the grain.
The grain bran surrounds the layer around the seed and it is a protective member for germination and the storage of the food. The bran is consisted of two layers, named Pericarp and Testa. The thickness of the bran has a considerable role in flour extraction.
- a) Pericarp or the first bran
The first bran is made up of a thin sheet called epidermis. There is a protective layer on the epidermis which is a combination of alcohol and wax and reduces the bakery value of the wheat.
- b) Testa or the second bran
It is consisted of two parts: 1. The brown layer which is made of two very dense cell layers, which have color.
- Hyaline layer which is located between testa and Aleurone layer and it is colorless.
- Trichomes (hair fibers)
Trichomes are in the upper part of the grain. Their color is varied in different grains and it is pale yellow or brown in the wheat.
Different cereals can be distinguished from their characteristics.