Our Unique Drying Process
Refractace Window Process
The exclusive drying process our harvesters
use is called Refractance-Window
In this picture you can see AFA drying in the Refractance-Window Drying Machine (AFA, or Aphanizomenon flos-aquae, is the scientific name for Blue Green Algae)
Refractance Window technology is a proprietary drying method that uses a heat transfer process and specific properties of water to gently remove moisture while maintaning the maximum integrity of the natural material.
When water is placed over a heating source, infrared energ is transfered throughout the water by convection. The heat energy then radiates from the wanter, primarily through evaporation.
When water is covered by a transparent membrane such as plastic and placed over a heating source, evaporation and its associated heat loss are blocked or “refracted”, and only conduction occurs. The plastic membrane acts like a mirror reflecting the infrared energy back into the water.Â
But when a moist raw material is placed on the plastic membrane’s surface, the water in the material creates a “window” that allows for the passage of infrared energy through the material. Heat behaves as if there were no membrane in that location, and is directly transferred to the water present in the material
In a matter of a few moments, the water in the material on the plastic membrane’s surface evaporates, and the “window” of infrared energy closes and “refracts” back into the heated water source, no longer exposing the material to heat.
Refractance Window (RW) Drying Process
During the RW drying process, moist raw material (Aphanizomenon flos-aquae) is applied on the surface of the drying system’s conveyor belt. The belt is a food grade Mylar (transparent polyester film) floating on the surface of a heated cistern containing circulating hot water. The heat from the cistern’s water is conducted by way of a “refractance window” through the Mylar belt to the water present in the raw material laying on the belt’s surface.
As the material travels down the conveyor, the water in the material evaporates through the “window” in the matter of few moments, with the “window” closing in proportion to the rapid dissipation of water in the material. Because the Mylar conveyor belt is a poor heat conductor, once the material dries, the “refractance window” closes, and only a minuscule amount of heat is transferred to the product as it is carried to the end of the conveyor system.
Raw material dried through the RW process delivers a flaked product close to its natural state. This expedient drying method protects the product’s delicate nutrients, color and flavor.
Because the RW drying process maintains the temperature of the raw material far below the temperature of the water circulating beneath the conveyor belt, its precious nutrients are protected from oxidization.
During the process, heat is applied to the material at 72°C for only three to five minutes
This drying method is superior to competitor’s freeze-drying and spray-drying methods in the preservation of the natural state of Aphanizomenon flos-aquae. Freeze-drying techniques expose raw material to heat ranging from 30°C to 64°C for twenty-four straight hours.
Spray-drying techniques apply heat to raw material ranging from 150°C to 300°C. Both methods can cause significant nutritional loss to the raw material being dried. Compare Hydro Dri™ dried product quality to freeze-drying and spray-drying.
When comparing various drying technologies, the degree of preservation of a material’s original color and flavor indicates the quality of the drying process utilized. Studies performed at Washington State University’s Department of Biological Systems Engineering and Department of Food Science and Human Nutrition established the preservation superiority of the RW drying technology over ALL other methods of drying, including freeze-drying.
