Freeze-drying

Freeze-drying is a method of food preservation. It is not to be confused with dehydration (such as the type of dehydrated foods called “Pot Noodles” found in supermarkets), which certainly are less expensive but are also less appetising (in taste and texture), maintain less nutritional value and have a shorter shelf life.

NASA has been one of the first consumers of freeze-dried products as food. Astronauts need good quality food and space shuttles are limited regarding the weight and volume.

›› Advantages

• The main advantage of freeze-drying is that the food retains its structure and flavour.
• Refrigeration is not required to conserve the freeze-dried foods.
• The weight of food is also reduced by freeze-drying, which is an advantage for transportation.
• The re-hydration of dried foods is completed very quickly because they have a very porous texture.

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• ›› Disadvantages

• This method is very expensive. It takes about 1500 kWh of energy to extract a ton of water. In addition, the equipment required (including the freeze dryer) is very expensive.
• Because of the costs involved, the conversion for everyday food products is impossible. However, the freeze-drying method is useful for all meals for sporting activities and outdoor pursuits as well as food for astronauts.
• Foods that consist of large elements can be treated, but they require too much energy to produce, so the price is very expensive. Generally freeze-drying is limited to food consisting of smaller elements.

Sachets can be stored freeze dried, generally between 2 and 5 years from their date of manufacture.