Exploring the relationships between flour protein chemistry and dough rheological properties

Dough, in the most basic sense, is made by combining water, flour and energy. Water causes flour proteins to swell, and the addition of mechanical energy allows them to become organized into a continuous protein network that gives dough a unique viscoelastic structure. Understanding of the influence of the dough deformation (extensional or shear) involved in terms of energy input, as well as the role and availability of the protein molecules involved in the process, is limited. The influence of energy level, type of deformation (extensional vs. shear), and strain history on dough development have been investigated by mixing powdered ice and flour under low temperature conditions. Relationships were examined among the rheological. properties of nondeveloped, partially-developed and developed dough samples, and the protein chemistry was studied for each respective dough stage. Microstructures of the samples were observed by scanning electron and laser scanning confocal (LSC) microscopies. Dynamic rheological data revealed that developed dough had the highest G* (most elastic or strong), followed by doughs partially developed with extensional deformation and then shear deformation, and finally by nondeveloped dough. The LSCM z-sectioning (scanning of different layers of the sample) and the analysis of amount of protein network showed that developed dough had the most protein network, and nondeveloped dough had the least protein network. Moreover, the type of deformation appeared to contribute to the development of protein network and further increase the dough strength. A combination of shear and extensional deformations by Farinograph produced the most protein network and the strongest dough, followed by extensional deformation, shear deformation, and then no deformation. This information should help further understand the roles that wheat proteins play in the quality of baked products.