You should never heat up cat food in the microwave. It kills the nutritional value of the food. I think they even mention this on the packaging. At least Nature's Variety brand does. Just put in a ziplock sandwich bag and place into a bowl of warm water. It should warm up pretty quickly. If you're freezing, then take out what you would feed the night before and place into a baggy, then place in the fridge.I find it funny that you didnt have any problems when you heated it up. Everytime i put the food in the microwave to heat it started flashing. Meaning too much metal in the cat food. So are they shards of Metal in this food. How sad i will not by this . ill buy real chicken and cook it myself.