Bread production

Bread production involves a series of unit operations comprising dough mixing, moulding, dividing and panning, proving, baking, cooling and wrapping. Measurements of final product quality are made, typically after baking, and few measurements are made at intermediate stages of processing (e.g. dough properties). The quality of the final product and the processing requirements of the dough are critically dependent on the flour properties. Flours are therefore supplied to specifications, typically measured by the supplier using laboratory methods including NIR and reference methods, supplemented by on-line NIR measurements. Relevant specifications include protein content and water absorption, which determine dough-handling characteristics after mixing, and the rheological characteristics of the dough and its ability to retain gas during proof and baking. Mixing is performed as a batch operation and is critical to final product quality. During this process, the ingredients are combined in weighed quantities, the dry ingredients absorb water, the protein structure is developed to form an elastic gluten network and air bubbles are entrained into the dough. Ingredient temperatures are measured and controlled to achieve the required final dough temperature, important for dough handling. The mixing time and the amount of mechanical work applied to the dough have a critical effect on the development of the required dough rheological properties. The optimum time and work input requirements depend on the properties of the flour, but these are not monitored on-line and mixing is normally done for a fixed time based on the flour specifications or, in some cases, to a fixed work input based on on-line measurement of power consumption..