Staling, or “going stale”, is a chemical and physical process in bread and other foods that reduces their palatability.
Staling is not, as is commonly believed, simply a drying-out process due to evaporation.
For example, bread will stale even in a moist environment, and stales most rapidly at temperatures just above freezing.
Bread stored in the refrigerator will have increased staling rates and should therefore be kept at room temperature.
However, refrigeration delays the growth of mold and extends the shelf life of bread. (source)
Can hamsters eat stale food?
Yes they can but as you can imagine it is not the best quality food for them.
Better to feed them fresh food. steer clear of moldy food.
Stale food doesn’t provide a health risk to them and if they don’t like it they will soon leave it alone.
Although hamsters will pretty much eat anything they can regulate themselves well.