Two different mechanisms are commonly referred to as the causes of staling. These are retrogradation (recrystallisation) of starch and the redistribution of water between starch and gluten. Whereas the staling of the crust is related to a change in water content, staling of the crumb occurs without any change in water content. Nevertheless, it causes a change in texture and a loss of aroma. Some of the changes that occur during staling can be reversed by reheating to temperatures of 50–70 8C