ABSTRACT
Nomenclature ..................................................................................................................... 329
References .......................................................................................................................... 330
Food in a microwave oven absorbs the microwaves and thus is directly heated by the
microwaves. Dry air does not absorb microwaves and therefore stays cold. The air in the
cavity tends to cool the food surface while warming up in the process. The eventual increase
of food surface temperature from absorbed microwave energy also increases evaporation of
water from it into the air. The airflow pattern inside the microwave oven determines the rates
of surface heat and moisture transfer and the distributions of temperature and moisture in the
food, thus determining its final quality from the heating process. For example, surface
moisture accumulation in microwave heating that often leads to an undesirable soggy food
product can be significantly reduced by increasing the airflow rate over the food [1]. In turn,
the evaporated water is convected away by the air and may reduce the oven efficiency due
to microwave absorption when accumulated in the cavity. A good air exchange is required to
prevent such effects.
