the cupboard. Science Molecular and physical composition Pasta exhibits a random molecular order rather than a crystalline structure. The moisture content of dried pasta is typically around 12%, indicating that dried pasta will remain a brittle solid until it is cooked and becomes malleable. The cooked product is, as a result, softer, more flexible, and chewy. Semolina flour is the ground endosperm of durum wheat, producing granules that absorb water during heating and an increase in viscosity due to semi-reordering of starch molecules. Another major component of durum wheat is protein which plays a large role in pasta dough rheology. Gluten proteins, which include monomeric gliadins and polymeric glutenin, make up the major protein component of durum wheat (about 75–80%). As more water is added and shear stress is applied, gluten proteins take on an elastic characteristic and begin to form strands and sheets. The gluten matrix that results during forming of the dough becomes irreversibly associated during drying as the moisture content is lowered to form the dried pasta product. Impact of processing on physical structure Before the mixing process takes place, semolina particles are irregularly shaped and present in different sizes. Semolina particles become hydrated during mixing. The amount of water added to the semolina is determined based on the initial moisture content of the flour and the desired shape of the pasta. The desired moisture content of the dough is around 32% wet basis and will vary depending on the shape of pasta being produced. The forming process involves the dough entering an extruder in which the rotation of a single or double screw system pushes the dough toward a die set to a specific shape. As the starch granules swell slightly in the presence of water and a low amount of thermal energy, they become embedded within the protein matrix and align along the direction of the shear caused by the extrusion process. Starch gelatinization and protein coagulation are the major changes that take place when pasta is cooked in boiling water. Protein and starch competing for water within the pasta cause a constant change in structure as the pasta cooks. Production and market In 2015–16, the largest producers of dried pasta were Italy (3.2 million tonnes), the United States (2 million tonnes), Turkey (1.3 million tons), Brazil (1.2 million tonnes), and Russia (1 million tons). In 2018, Italy was the world's largest exporter of pasta,