*3.1.3.5 Barley protein*

Barley crop is a very adaptable crop. It is cultivated for both animal feed and brewing industry, in which, the by-product becomes livestock feed. Barley crops and by-products are rich and affordable protein sources which include 8–13% and 20–30%, respectively [109]. Barley proteins composed of two major protein fractions: hordein and glutelin (about 35–55% and 35–40%, respectively). Hordein fraction (alcohol extracted fraction) is divided into five groups - B hordein, C hordein, γ-hordein, D hordein, and A hordein - based on their amino acid compositions and electrophoretic mobility. On the other hand, glutelin is an alkali-soluble protein after hordein extraction, so it is not possible to extract glutelin fraction free from hordein fraction contamination. Barley proteins are highly hydrophobic and they exhibit excellent foaming, emulsifying and film-forming properties indicating that the emulsifying-stabilization process can prepare micro- and nanocapsules from barley protein [110–112].
