The objectives of this study were to evaluate whether proofing profile influences volume and crumb firmness in bread baked from frozen dough, and whether rye or sugar content and different kneading times affect the microstructure of the frozen dough. Microscopy was used to explain the differences.Wheat doughs mixed with rye ("rye") and with sugar ("sweet") were frozen after 3 different proofing times (0, 18, and 38 min) and visualized with confocal laser scanning microscopy and 3-dimensional micro-computed tomography. The baked breads were evaluated for volume and texture. Breads from un-proofed frozen dough allowed to proof after thawing showed the highest volume (4.0 cm3/g) and the softest crumb texture. The pre-proofed sweet bread had firmer crumbs and lower volume (2.5-3.0 cm3/g) than the pre-proofed rye bread (2.7-3.7 cm3/g). Reasons for the differences in quality parameters between the rye and sweet breads were investigated by studying the different influences of kneading time and sugar content on fresh and frozen dough. The gluten network was found to be more homogeneously distributed in doughs with longer kneading times and lower sugar content, and less well distributed and more lumped in frozen than in fresh dough.