Water mobility and association by 1H NMR and diffusion experiments in simple model bread dough systems containing organic acids

Reducing the sodium content of bread to meet desirable population health outcomes can lead to challenges dough processing, poor dough handling and rheology, and high stickiness. Our objective was to better understand the relationship of water and the dough components in low sodium dough environments. The water mobility, association, and diffusion characteristics of simple model doughs containing reduced NaCl (1% by flour wt.), organic acids (acetic, fumaric, or succinic at 1.2 mmol/100 g flour or a no acid control), and a dough improver (0.001% by flour weight glucose oxidase) using two cultivars (Pembina and Harvest) were assessed by 1H NMR. It was determined that the inclusion of the acids did not significantly affect the overall structure of the dough; the polymer backbones (protein and starch) were not significantly affected, however, the inclusion of acids or use of a stronger cultivar (Pembina) reduced molecular motion on the MHz timescale as assessed by T1 and T2. Motion on the kHz timescale was also altered. Samples which contained acid or were made from Pembina flour had less mobile water than those without acids, or doughs prepared with Harvest flour. The diffusion characteristics of water in the doughs were not altered by the acid or cultivar; however, diffusion was determined to be confined/restricted by the polymer matrix. Overall, the inclusion of acids alters molecular motion and interactions with the side chains of the polymer backbone, and further stickiness and handling investigations should focus on these areas to expand upon the relationship of water and stickiness/dough handling, which is a concern in low sodium doughs.