Cereal scientists have been analyzing baking functionalities of wheat flours and doughs by studying structure-function of gluten proteins since their discovery back in the 1700s. Although it had long been recognized that doughs must contain air bubbles for baking breads, the role of gas bubbles was not adequately understood, primarily due to lack of suitable visualization methods. Recent advances in three-dimensional, x-ray tomography techniques have made it possible to visualize gas bubbles in doughs and void structures in breads. In addition, the use of Synchrotron tomography has enabled visualizing the mechanics of bubbles in doughs in real time. Percolation model has been found to adequately capture flour quality effects on dough fermentation and crumb qualities of baked breads. In this paper we would summarize the findings from the visualization studies, and present the new ideas for flour functionality, that tie in dough structure with bread crumb qualities. The following would be highlighted: (1) bubbles are mobile in doughs, not trapped by gluten, (2) bubbles coalesce and disproportionate in all doughs forming clusters with rate of coalescence being higher in leavened doughs, (3) In unleavened dough, as dough rests, dough porosity increases from poro-visco-elastic relaxation of gluten, (4) In yeasted doughs, a single, massively inter-connected, closed cluster forms, percolating at ~26% dough porosity irrespective of flour type in dough, (5) the single, closed bubble in doughs likely converts to the single, massively interconnected, open bubble that is present in breads accounting for >99% of bread porosity, (6) the size and shape distribution of bubbles affect the rate of dough fermentation and subsequently, crumb qualities of baked products and, (7) the rheology and physical properties of dough liquor, significantly governed by the quantity and quality of non-starch polysaccharides in flours, influence the rate of coalescence of gas bubbles and thereby the bake qualities of flours. Overall, dough is proving to be a viscoelastic, microfluidic foam with gluten providing the soft walls and the tortuosity to the flow of dough liquors carrying dispersed gas bubbles that ultimately define the appearance of crumb structures in breads.