What is Refractance Window Drying?
Refractance Window drying is a safe way to dehydrate fresh whole foods. It gently extracts water from our foods while preserving vitamins, minerals, and micronutrients.
In a Refractance Window Dryer, the food is not directly exposed to extreme hot or cold temperatures during drying. It is instead based on the transfer of thermal energy from warm water to food. This continues until a precise point of dehydration is reached, at which point the drying process automatically stops.
Because Refractance Window Drying is a gentler process, it has several advantages over other common dehydration methods like spray drying or freeze drying. The dried food retains all of the nutritional properties of its fresh, raw-food equivalent because it is only briefly exposed to non-damaging temperatures and is never subjected to pressure or shear force.
How does A REFRACTANCE WINDOW DRYER work?
Science! Water is a fantastic conductor of energy – ever grab a pan out of the oven with an oven mitt that’s gotten damp? Hot stuff!
In Refractance Window Drying, we use this same principal to dry our foods. The wet Food State Nutrient is placed on a mylar belt above a body of warm water. As the thermal energy from the water below the belt travels upwards, the water content of the foods conducts this energy through the belt and thus the food, allowing for its own water content to evaporate. As the food continues to travel down the belt, the amount of water in it decreases until it reaches about 3%. At this point, there is no longer enough water in the food to conduct the thermal energy from the water below the belt, and the “window” closes. The belt refracts the thermal energy back into the water rather than through the food until it reaches the end of the line. And there you have it – food gently dried to the perfect level of dehydration!
A slurry of liquid product is evenly applied to the top surface of a continuous sheet of transparent plastic. This impervious conveyor belt floats on a surface of hot water (210° F / 99° C or less).
Our proprietary process allows infrared energy (inherent in the circulating water beneath the belt) to pass at the speed of light directly into the liquid slurry. The “window” allowing the rapid transfer of infrared energy closes as the product loses moisture. Heat is also conducted through the belt, which aids to evaporate moisture in the product, especially when the product is nearly dry. Infrared energy and conducted heat permit rapid drying at atmospheric pressure rather than under a vacuum. This rapid, yet gentle process provides superior retention of a product’s beneficial properties, including its nutrition, flavour, colour and aroma.
Energy efficient and with low water use, Refractance Window® drying preserves air quality in and around the drying facility because little product essence is lost. In addition, the process does not generate exhaust dust, a significant pollution problem.
Many factors affect drying characteristics and rates. It is important to test-dry a product utilizing our Test and Contract Processing services.
Applications of Refractance Window Dryer
➢ Pureed fruit and vegetable
➢ Herbal formulations
➢ Egg mixtures Meat powder
➢ Nutraceutical Cosmetics
Advantages of Refractance Window Dryer
➢ Lower operation costs
➢ Shorter drying times
➢ No cross-contamination occurs
➢ Requires 50–70% less capital and 50%less energy than the freeze drier
➢ Reduction from 4 to 6 decades of microbial load Better quality of dried products