Analytical and sensory studies on the release of sodium from wheat bread crumb.

As a basis for sodium reduction, interactions between sodium and wheat bread ingredients and their impact on salt perception in bread crumb were examined. The theoretical sodium binding capacities of wheat proteins revealed that a maximum amount of 0.24% NaCl (based on flour) could be bound in bread crumb by ionic interactions between sodium ions and acidic amino acid side chains. However, the sodium binding capacities of wheat proteins, determined by a magnetic beads assay and a sodium-selective electrode, were only about 0.002% NaCl. They were negligible concerning the sensory perception of saltiness, as 0.075 and 0.3% NaCl were the lowest noticeable differences using bread containing 0 and 1% NaCl as a reference, respectively. Extracting bread crumb in a mastication simulator with ultrapure water, buffer solutions, and artificial and human saliva revealed that interactions between sodium and wheat bread ingredients were sufficiently weak to enable complete sodium extraction during simulated mastication.