Freeze-drying: advantages and disadvantages

The purpose of freeze-drying and dehydration is to remove water from food so that it can be kept for a longer period of time, while preserving its nutritional properties as much as possible. Indeed, the presence of water favours the appearance and development of harmful micro-organisms.

Drying food in the sun or wind is an ancient technique for preserving food outside of harvest periods. You can experiment with dehydration at home by putting slices of dried fruit in your oven (apples, mushrooms, etc.), provided you are patient: food should be left to dry at low temperatures for a long time so that it is not cooked. Professional dehydrators are available for sale, but their cost can be high.
Freeze-drying or dehydrating food makes it lighter and more compact, and therefore easier to transport!

>> Dehydration is the partial evaporation of water from a food, which concentrates its nutrients and slightly alters the nutritional properties. The food can then be stored for about 2 years and then easily rehydrated with hot water.

>> Freeze-drying is a form of cold dehydration: it begins with a freezing phase and then total dehydration called sublimation. Freeze-drying has the advantage of better preserving the nutritional qualities and taste, guaranteeing a longer shelf life and allowing rehydration in hot OR cold water, which is practical in the event of problems with heating the water. In fact, there is a freeze-dried product that you probably already have at home: instant soluble coffee!

Freeze-drying was developed in 1906 by two Frenchmen: Frenchmen Arsène d'Arsonval and Frédéric Bordas. This technique was later used by NASA to easily preserve food and feed astronauts.

The main stages of freeze-drying:
1 - Freezing: the food is frozen at a temperature of about -40°
2 - Sublimation: this is a stage in the process that removes the water from the food before it becomes liquid again, in an airless environment. It passes directly from a solid state (ice) to a gaseous state.
3 - Packaging: freeze-dried foods are preserved in bags that protect them from the air (especially from oxygen which oxidises the food) and from humidity to guarantee a long shelf life.
Would you like to know how Forclaz freeze-dried meals are made? We open the doors of one of our industrial partners, located in France in the Landes:

We believe that freeze-drying is the solution that best meets the needs of self-sufficient adventurers, as it means we can offer nutritious, light and easy to rehydrate meals.

Among the many benefits of freeze-dried meals, you will find:
- Nutritional properties : Unlike other manufacturing processes, freeze-drying retains around 95% of the nutritional properties as it does not use heat. In addition, the meals are prepared according to the nutritional needs of athletes: we estimate thata trekker needs about 3,000 to 4,000 kcal per day of trekking.
- Easy to carry: the dehydration phase (sublimation) transforms the food and it gains in weight and volume.
- Fast and easy to use: to rehydrate your dishes, you don't need many utensils. All you need is a pot, a stove and some water!
- Variety of dishes offered: the range of freeze-dried meals is very wide and varied, with recipes developed with the utmost care. There is something for every taste and for all eating habits (gluten, vegetarian, etc.). More comforting and nourishing than the classic pasta with water!
- Long shelf life: freeze-dried meals can be kept for 15 to 25 years, if good storage conditions are observed. In comparison, dehydrated meals are estimated to have a shelf life of about 2 years.

However, it’s important to note that not all freeze-dried products are created equal: some do not contain preservatives or additives, more or less attention is paid to the salt content, the origin of the food varies from one producer to another, etc.

The preparation of a ready meal, the freezing, the vacuum for sublimation, the packaging... all these steps require resources and machines that have a cost!
Freeze-dried dishes are therefore more expensive than a home-made meal: allow between 5 and 9€ per dish.

Before leaving on a trek, buy different bags of freeze-dried food and test them at home to choose your favourites and to determine whether you like your food with more or less water.

Preparing a freeze-dried dish is extremely simple: open the bag, pour in hot water up to the mark on the packaging, or a little less, you can add more, but not take away. Then close the bag and follow the preparation time indicated on the product. Stir, it's ready!

A small important detail: the heat of the water. The hotter your water, the better the rehydration. If the water is not boiling, wait a few minutes more before tasting your dish.