Better energy efficiency and dried product quality can be obtained by microwave drying which provides a higher drying rate than hot air drying. Microwave energy can be directly absorbed by moisture in drying material and lead to heat generation within material by two mechanisms, i.e. dipolar rotation and ionic conduction, caused by altering the electromagnetic field. The high heating rate of microwaves raises the product temperature rapidly, causing high vapour pressure to develop inside the product,resulting in a very rapid transfer of water to the surface of the product.