Coffee can be reheated in the microwave, but this heating process can alter its taste. Coffee heated in the microwave may also taste burned or stale.
Coffee that has been brewed can be safely stored in the refrigerator for 3 to 4 days before it is discarded. Coffee should not be placed in the freezer.
If day-old coffee contains creamer or dairy products and was left out at room temperature, it should not be reheated. Dairy products that are not refrigerated for long periods of time should be thrown out.Learn more about Coffee & Tea