Formation of gluten-based dough requires the presence of gluten proteins, gliadin and glutenin, moisture, and energy. Gliadin and glutenin proteins are storage proteins that accumulate in wheat endosperm cells during grain filling. Gliadins are a heterogenous group of single chain proteins that are responsible for dough cohesiveness. Gliadin proteins can be separated using electrophoresis into four groups: α-gliadins, β-gliadins, γ-gliadins, and ω-gliadins. α-Gliadins, β-gliadins, and γ-gliadins contain intrachain disulfide bonds, whereas ω-gliadins lack cysteine residues, a sulfur containing amino acid, and so cannot form disulfide bonds.
Gliadins are considered to be non-aggregating, meaning that their polymer chains do not interact to form large polymeric complexes. Glutenins are a heterogenous group of multichain proteins that are responsible for dough strength. Glutenin proteins can be classified into two groups: the high molecular weight glutenin subunit and the low molecular weight glutenin subunit. Glutenin proteins can form large polymeric protein complexes as a result of entanglements of long polymeric chains and their ability to form interchain disulfide bonds1.
Moisture is needed for dough formation. Gliadins and glutenins are packed very tightly in the protein bodies found in endosperm cells. As these proteins hydrate, they begin to expand, change their steric configuration, and expose reactive sites2. Thus, water acts as a plasticiser, increasing the intermolecular space and flexibility of gliadin and glutenin proteins allowing them the possibility of interacting with each other when the energy in the form of mixing/kneading is applied. Without mixing/kneading, the collision of glutenins and gliadins with each other will not take place. Mixing energy allows gliadins and glutenins interact with each other through disulfide bonds formed between their cysteine residues. The result of the simultaneous occurrence of gliadins and glutenins, moisture, and energy is the formation of a protein network that surrounds starch granules and provides the mechanical strength of pasta products.