Functional and Film-forming Properties of Fractionated Barley Proteins

Abstract

Barley proteins are expected to have unique functional properties due to their high content of alcohol soluble protein, hordein. Since the barley proteins obtained by conventional isoelectric precipitation method cannot represent hordein fraction, barley proteins were fractionated to albumin, globulin, glutelin, and hordein with respect to extraction solvents. Functional properties and film-forming properties of solubility-fractionated barley proteins were investigated to explore their potential for human food ingredient and industrial usage. The 100 g of total barley protein comprised 5 g albumin, 23 g globulin, 45 g glutelin, and 27 g hordein. Water-binding capacities of barley protein isolates ranged from 140-183 mL water/100 g solid. Hordein showed the highest oil absorption capacity (136 mL oil/100 g), and glutelin showed the highest gelation property among the fractionated proteins. In general, the barley protein fractions formed brittle and weak films as indicated by low tensile strength (TS) and percent elongation at break (E) values. The salt-soluble globulin fraction produced film with the lowest TS value. Although films made from glutelin and hordein were dark-colored and had lower E values, they could be used as excellent barriers against water transmission.