3D quantitative investigation of wheat starch morphology from bread dough to crumb

In this work, the morphology of wheat starch granules in dough before and after baking was investigated using three-dimensional (3D) confocal laser scanning microscopy (CLSM), with a particular focus on gas cell walls (GCWs) of varying thickness and integrity (intact and partially ruptured) located in the loaf’s core. The image stacks were acquired over depths ranging from 20.2 μm to 40.8 μm. Individual starch granules were segmented and analyzed in 3D, enabling quantitative characterization of their size and morphology. In total, 1,131 granules were analyzed across the six samples. Compared to raw dough, the Feret diameter of starch granules increased by approximately 1.5-fold in thick GCWs, for both B-type (8 to 12 μm) and A-type starch granules (24 to 36 μm). Granule swelling was moderate and occurred preferentially along the direction of gluten extension within GCWs, providing direct evidence of a directional coupling between starch granule and gluten network deformation in a real dough system. Additionally, a small proportion of granules exhibited internal softening within a poorly extensible outer envelope; a comprehensive scheme has been produced to unravel the underlying mechanisms during baking. These results provide new quantitative and three-dimensional insights into starch behavior in the vicinity of gas cell walls and contribute to a better mechanistic understanding of bread structure development during baking. • 3D measurement of the evolution of starch granule size from dough to crumb • Evaluation of gas cell walls of different thicknesses in the loaf’s core • Moderate starch granule swelling accompanies gluten deformation • Inter-granular variability in deformation relates to water availability