Freeze drying occurs in three phases

1

Freezing

2

Primary Drying (Sublimation)

3

Secondary Drying (Adsorption)

Benefits of Freeze-Drying

1) Whole Food Nutrition: Retained nutrients, retained flavors with no requirement of preservatives or additives to the food.
2) Closest to the fresh form: Actual color, aroma, flavor, taste and consistency of foods are retained. Very simple to rehydrate to the original form.
3) Light weight: Very convenient to carry or transport because of the light weight of the finished foods. 
4) Longer shelf life: Any of the freeze-dried food can be kept at room temperature, including meat, eggs and fish.
5) Customization: Ready curries or any other dishes can be freeze-dried. All you have to do is rehydrate before consumption or cooking.