The freeze-drying food has a long history, longer than a thousand years old, as peoples living high in the mountains where the combination of cold temperatures and (low pressure) high altitudes would enable the water in foods to freeze, then sublimate in a natural setting.

Indigenous people in Bolivia’s mountains figured out how to clean poisonous potatoes of their toxins & freeze-dry them for preservation and transport purposes. They did this all without using pumps, pipes or freezer technology of any kinds. The Aymara Indigenous people have been preparing freeze-dried potatoes the same way since they invented their process more than 1,500 years ago.

Freeze-dried foods are healthy, lightweight, retain the original food’s color and taste, won’t spoil for years and most importantly, retain the macronutrients, micronutrients and phytonutrients remarkably well.

Studies (1, 2, 3) have shown that freeze-dried foods are super nutritional and often retain over 90% of the original fresh food’s nutrition, much more than other drying techniques (air-drying, heat-drying) which usually damage micronutrients and phytonutrients — as easily seen by the large changes in the food’s colors.

With the wide application of freeze dryer, freeze dried food is becoming more and more popular all over the world and home freeze drying is now finding immense popularity across Canada and around the world.

Vegetables, fruits, meat, fish, spices, etc. are being freeze-dried are finding their way into homesteading and prepper groups around the world, but also being used in aerospace, mountaineering, tourism, exploration, mining and other industries including various restaurants and eateries.

Freeze-drying is a drying methods that preserves food. The main reason for the damage, decay and deterioration of food is caused by two factors: external cause (such as the effect of air, water, temperature, biology, etc.) and internal factor (such as the metabolism of biomass itself). If the effect of external and internal causes can be limited to a lesser extent, the goal of leaving the goods unchanged for a certain period of time can be achieved.
In addition, a freeze dryer is very suitable for handling biological products, such as blood, because it does not operate at a high temperature, which can prevent biological products from deteriorating.

In general, the products obtained after drying have problems such as shrinking volume and hardened texture. Most volatile components are lost, some heat-sensitive substances are denatured, inactivated and some substances are even oxidized. As a result, the dried product has a significant difference in properties compared to before drying. On the contrary, freeze-drying is basically carried out below 0 °C in which state the product is in a frozen state. Only at the later stage, when the residual moisture content of the product needs to be reduced, is the product raised to a temperature above 0 ° C, but generally not more than 40 ° C. In vacuum, when the steam is directly sublimated, the drug remains in the frozen ice sheet and forms a spongy loose porous structure. Therefore, after freeze-drying, the volume size is almost unchanged.

For the next use, as long as the injection water is added, it will immediately dissolve. By freeze-drying, because the moisture in the material exists in the form of ice crystal after pre-freezing, the inorganic salt dissolved in water is evenly distributed in the material. When the product treated with freeze dryer is sublimated, the dissolved material will be dissolved in water precipitation, avoiding the surface hardening phenomenon that is easy to occur in the usual drying method.

In general drying methods, the phenomenon of surface hardening caused by the precipitation of inorganic salt is carried by the migration of moisture from the material to the surface.