Freeze-drying: advantages and disadvantages

Food is a key point when preparing for a backpacking adventure. Freeze-dried meals are a popular choice for trekkers, offering a nutritious and easily transportable alternative.

Light, compact, nutritious and with a long shelf life, freeze-dried and dehydrated meals are excellent trekking partners.

What is the difference between dehydrated and freeze-dried?

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!

How are your freeze-dried hiking foods made?

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:

What is the purpose of freeze-drying and what are its advantages?

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.

Disadvantages of freeze-dried dishes

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.

How to prepare a freeze-dried meal when bivouacking?

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.

How to prepare a freeze-dried meal?

Other questions about freeze-drying:

How to store a freeze-dried product?

If you have opened and rehydrated a freeze-dried product but haven’t finished it, it’s recommended to keep it in the fridge. Not always easy if you’re trekking!
Otherwise, freeze-dried products are best stored in a dry place.

How much hot water should I add to a freeze-dried product?

Each product needs the right amount of water to provide the best possible final texture. This amount is indicated by a line inside the product packaging. You can choose to use a little less then test. Then add more, depending on the texture.

How to freeze-dry at home (strawberries, raspberries, apples, pasta, etc.)?

If you’ve read the above, I think you already know the answer: you can't make your own freeze-dried food at home. Or maybe you live in a laboratory with a room capable of vacuuming.

On the other hand, if you want to take strawberries on a bivouac, you can dehydrate them at home. Thanks to your oven or a dedicated machine like some restaurants use!

You will have understood: freeze-dried products are a bit more expensive, but it's all about the taste and nutritional properties! Buying freeze-dried products for trekking means you can eat hot food even when you are out in the countryside. This technique of keeping food preserves its taste and nutritional values. All you have to do is choose your dishes!

forclaz bivouac tips

The hiking, bivouac and backpacking team

The Forclaz team shares its advice and experience to help you prepare for your backpacking adventures.

Other tips that could interest you

Eating in a bivouac, what food to take on a trek?

Eating in a bivouac, what food to take on a trek?

Are you looking for advice or ideas for your meals on a trek? We explain all you need to know.

TREKKING RECIPE: velvety mushroom soup

TREKKING RECIPE: velvety mushroom soup

An easy-to-prepare dehydrated recipe for food lovers going on a bivouac!

The keys to a successful bivouac


Your bivouac needs to be well-prepared before pitching your tent in the middle of nature! Choice of equipment, location, preliminary information, practical advice: this guide will allow you step-by-step to combine safety and pleasure for your future nights spent outdoors.

An easy recipe for trekking


A delicious trekking recipe to carry in your backpack for a yummy bivouac experience!

How to use a gas stove

How to use a gas stove

Is this your first time using a gas stove? Here is a step-by-step guide on how to use it!

Choosing the right bivouac tent to go on a trek

How to choose a bivouacking tent

Going trekking, alone or with others, and don't know what type of tent to take? No worries, we are here to help you! Check out the main selection criteria !