In the microwave oven, food begins to cook from the outside first, the inside of the food relying on the slower conduction of heat. If food is cooked at a high microwave power level, it is possible that the heat may not have reached the centre of the food, so it is hot on the outside but cold in the centre. During the standing time, the heat is transferred to the centre of the food.
When heating food with different densities, such as with menu cooking, it is sensible to start with a low microwave power level and select a longer reheating duration.
