Retrogradation

Why does bread stale during storage?
Why does cooked rice harden during storage?
The primary cause is aging starch gel.
Students learn about the phenomenon retrogradation with Prof. Dr. Sibel Ozilgen as a part of 'Culinary Science' course at the Gastronomy and Culinary Arts Department, Yeditepe University. Starch molecules in gelatinized starch have a tendency to re-associate in an ordered crystalline structure during storage. This process is known as retrogradation, which is directly related to the hardening of cooked rice and the staling of baked products, such as bread. Storage temperature has a significant effect on the rate of retrogradation. Rate of retrogradation is higher at the refrigeration temperature than the rate at the freezing temperature and at room temperature.