Wheat proteins  Incomplete; low in essential amino acid (lysine)  Adequate amount of methionine  Often paired with legumes  achieve protein completion  Principle protein of wheat flour is gluten  Important property; form an elastic dough when moistened and mechanically worked  Gluten protein classified into 4 types  In wheat;  Storage protein of wheat endosperm Prolamins  Gliadin Glutelins  Glutenin

Gluten proteins Soluble in dilute acids or bases, detergents or dissociating/ reducing agents Soluble in aqueous alcohol Insoluble in pure water Soluble in dilute salt solutions, insoluble in high salt solutions Soluble in water / dilute in salt solutions Coagulated by heat AlbuminsGlobulins Glutelins Prolamins

Differences between Gliadin and Glutenin GLIADIN (Prolamins) MW Alcohol soluble (60-70% ethanol) Rich in glutamine, proline but little lysine Glutamine concentrated in certain regions play important role in cross linking molecule by formation of H bonds Intramolecular disulphides linkages Exist as single peptide chain Soft and sticky- gives gluten its viscosity and extensibility GLUTENIN (Glutelins) MW M Suspendable in ethanol Made up of subunit of varying molecular weights, joined together by disulphide bond Intra (within) and inter (between)molecular disulphides linkages Appear as large linear molecule More stable and tough-gives elasticity Albumin and globulin Low MW (12,000) Contains glycoprotein, mucoprotein, lipoprotein and variety of enzymes

Gluten  Produce from gliadin and glutelin in wheat flour by the process of hydration and mixing  Control the rheological or flow properties of dough  On hydration, gluten form a viscoelastic 3 dimensional network, embedded the starch granules  This network capable of retaining tiny cells of occluded gas, primarily air (during mixing ) and CO 2 generated by yeast cells

 Glycolipids bound to gluten proteins;  Glutenin by hydrophobic bond  Gliadin by hydrogen bond  Bind to starch in complex dough system  Glycolipids essential for functioning of gluten in producing a loaf of bread of good quality  Lubricating action on the gluten matrix by lowering the resistence of the dough to diffusion and expansion of leavening gas  Resulting in increased volume and improved grain