Freeze drying is a method of dehydration of frozen materials by sublimation under vacuum, and it could produce the high-quality dried foods.
Drying food in the sun is a safe and economical way to preserve food, especially plants and animals. To dry food in the sun, one needs to have both warm temperatures and a constant breeze.
Drying food in the room is different from sun drying. Here the food that has to be dried is placed in a well-ventilated room or covered space.
In microwave drying, drying time is shortened due to quick absorption of energy by water molecules, causes rapid evaporation of water, resulting in high drying rates of the food.
Conventional hot air drying is the most frequently used and low-cost drying method in the food industry. However, significant quality changes of dried products may occur during hot air drying (Rabeta and Lin, 2015).