Refrigeration and freezing retards the staling process. Such applications include strengthening dough, delaying bread staling, enhancing foam, and preventing microbial growth. Stale bread is colloquially called "dry", but drying and staling are distinct processes. Bread staling occurs when the starch components form hard crystals. Staling is not simply a drying-out process due to evaporation. Frozen bread, however, traps the moisture as ice, and prevents the staling process. Bread stored in a refrigerator will have increased staling rates. Retrogradation is directly related to the staling or aging of bread.