The effects of storage of bread doughs at constant temperatures of -10°C, -20°C or at -20°C with cycling to -10°C for 66 h per week were examined using low-temperature scanning electron microscopy. Significant yeast activity in doughs between mixing and storing for 1 day at -20°C was evidenced by the appearance of spherical voids in the stored, but not freshly mixed, dough. Dough structure became increasingly disrupted with frozen storage time, was more extreme at -10°C than at -20°C, and was even more so when temperature cycling was employed. The cause of disruption was apparently changes in ice-crystal structure as indicated by the appearance and increase in the size of angular voids in doughs during frozen storage. Changes to dough structure were also evidenced by changes to the gluten network, ultimately to the extent that starch granules were no longer associated with gluten fibrils.
- Frozen dough
- Low-temperature scanning electron microscopy
- Storage life