Freeze-drying (also called lyophilization) is a technique used to, among other things, keep food preserve longer, whereby the vitamins, minerals and other active substances are almost completely preserved.
Freeze drying consists of three steps:
In the first step, the product is frozen at very low temperatures (down to -80 C °). The low temperatures ensure that the product freezes quickly. In this way, smaller ice crystals are formed, and the quality is perfectly preserved.
When the product is frozen, the ice is removed at slightly higher temperatures under a vacuum by so-called sublimation. This ensures that the ice cream evaporates immediately, while the taste and texture are still optimally preserved.
Finally, the food is further dried, so that the last water present is removed.
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What are the benefits of freeze drying?
Freeze drying has several advantages:
- The nutrients are optimally preserved.
- The color, structure and texture of the product are retained.
- Freeze-dried food has a long shelf life, without the need to be kept in the refrigerator.
- Freeze-dried food is lighter in weight, so less energy is needed for transport.
- The freeze-drying process can easily be reversed by adding water to the freeze-dried product.
Where does freeze drying come from?
It is not entirely clear who invented the freeze-drying technique. According to some, the invention of freeze-drying dates back to the Inca tribes of South America. The Incas allowed food to freeze overnight at high altitudes and then let it dry in the sun. But freeze drying as we know it today is indebted to various inventions throughout history.
What is freeze drying used for?
Freeze-drying is mainly used to preserve foods with a limited use-by date. For example, it is used for instant coffee, soups or crunchy dried fruits such as strawberries. In addition, it is also used for biological applications, medicines, powders (vegetable or fruit-based) and expedition nutrition.
Are freeze-dried foods healthy?
Processed foods, in which foods undergo some form of processing before consumption, do not enjoy a good reputation. Processing can cause, among other things, that the nutrients present (or at least some of them) are lost. Moreover, additives such as preservatives and dyes are often used during processing.
In freeze-drying, however, no additives are added (at least not with the products of Stashed), while the nutrients present are almost 100% preserved. That is why freeze-dried food is considered very healthy by various scientific bodies. For example, according to research by the Institute of Nutrition and Functional Foods in Quebec, Canada, freeze-drying is one of the best methods of removing water from a product. In some cases, freeze-dried food is even healthier than “fresh” food, because the latter loses quality due to transport and then storing it at home.