What Is Freeze-drying?
Freeze drying is the process that involves the freezing and drying of foods to produce high quality products. This method involves freezing food first, and then drying it. Once a food is frozen, it undergoes the removal of water from it through sublimation process. This method is generally extensively applied in the pharmaceutical and food industries.
How Freeze-drying Works
Freezing – A food is first frozen by atmospheric pressure.
Primary drying– Then the sublimation process is applied to extract the frozen water from a food.
Secondary drying– Also referred to as desorption. It takes place after the initial drying, and aims to extract any bound water to achieve the anticipated humidity levels.
Which Foods Can You Freeze -dry?
Various food commodities including snacks are dried using this method. In fact , most ready-to-eat foods undergo freeze-drying. These foods include:
- Fruits
- Vegetables
- Dairy products
- Spices-basil, garlic , ginger
- Meat-beef, poultry, turkey
- Beverages -coffee, cocoa, tea
- Legumes -lentils, beans, peas etc
- Eggs
- Desserts
Is Freeze-drying A Food Preservation Method?
Freeze-drying preserves food in addition to enhancing its quality. Whilst it will only slow down micro-organisms instead of destroying them completely, this method extends the shelf-life of foods as through drying, a food’s water content is reduced.
Freeze-drying And Cooking Time
Usually, the freeze-drying method sigificantly reduces the amount of time taken to prepare and cook a food. Basically, the food has already been cooked through the drying process. A food may have required a longer time to cook but when it is freeze-dried, its cooking time can be reduced significantly compared to what it would have taken for a similar food that has not been freeze-dried.
Does freeze-drying affect the nutritional value of foods?
Whereas freeze -drying can lead to nutrient losses, it is usually not very significant. Freeze-drying does not also significantly impact the appearance and texture of a food.
Freeze-drying is not only a food preservation method but one that also promotes easy handling and less cooking time for some foods.