The freezer coffee is coffee which is brewed and then freeze-dried . It is a powder that can be dissolved in hot water (max.82c) so you get coffee. This product has been through some processes to get the taste so close to real coffee. The caffeine from the coffee beans is retained in this beverage. Freeze drying is a way to dry different products. The fundamental principle of freeze drying is sublimation.
Freeze drying of coffee.
The coffee liquid is frozen to minus 40 degrees C, causing the water particles in the concentrated coffee to form ice crystals. In a method known as sublimation , the ice is extracted from the frozen granules in a special chamber which dries the particles at very low pressure and back is the soluble coffee.