Complexity and Power of a Harvest Right Freeze Dryer

A Harvest Right Freeze Dryer is an amazingly complex piece of equipment that is relatively simple to operate. However, under the covers, it is exponentially more powerful and complex than a refrigerator, a freezer, or a dehydrator. The Harvest Right Freeze Dryer combines several significant systems and devices to allow the system to make freeze-dried products. The following describes some of the technologies used:

• The freezing part of the process is critical to the success in making freeze dried products. Most freezers can only get down to -10 degrees Fahrenheit; whereas, Harvest Right’s patented freeze dryers can cool to -50°F (-46°C). Early in the development of the freeze dryer, refrigeration experts repeatedly told Harvest Right’s engineers that it would be impossible to reach temperatures that low by just using single stage condensing units.

• The second significant technology for freeze drying is a powerful vacuum pump that is capable of reaching low pressures between 100 and 300 mTorr. This very low vacuum (like outer space) makes it possible to boil water at around 0°F. Because of this, water sublimates (evaporates) from the food while the food is still frozen. The benefit of drying food and other products at a low temperature and pressure is that the nutrition, taste, shape, and color of the food are all preserved. The food can then be easily rehydrated to a near fresh state.

• The third technology in freeze drying is the addition of heat to the food within the vacuum chamber to accelerate the evaporation/sublimation process. The Harvest Right shelf unit provides a place for trays of food to slide into the chamber. There are controllable, powerful heaters under each shelf that slightly warm the trays of the product for accelerated evaporation/sublimation of the frozen water in the cells of the food. This is part of the process that gets all the water out of the food without damaging its nutrition, flavor, color, or shape.

• Finally, in order to control all of the above components during freeze drying, there is a computer that manages the entire process. The computer is powerful and the software well designed. It takes into consideration the variables of time, temperature, and pressure. Sensors are needed to give the computer feedback regarding the temperature of the food as well as the vacuum pressure in the chamber. The computer and associated software entirely manage the process of freeze drying. It doesn’t matter what food is placed in it, the freeze dryer will dry it automatically without requiring human assistance or interference. No other freeze dryer in the world has this capability. It is possible to have different items on each shelf. The unit will dry each perfectly.

• Additionally, the water vapor that evaporates (sublimates) out of the food needs to have a place to go. It is important to minimize the water vapor being pulled into the vacuum pump as it will, over time, destroy the pump. So, Harvest Right has built an ice trap that catches the evaporated water before it goes into the vacuum pump. Then, after the freeze dry process has finished, this ice is then melted through an onboard defrost process and allowed to drain out of the ice trap so the freeze dryer is ready for the next batch of product.

There are few, if any, appliances in the world that are as complex and capable as the Harvest Right Freeze Dryers. They are remarkable products.