Sublimation Drying — A Miracle That Preserves Soul Of Food
People must have tried food that going through the sublimation drying process, sublimation-dried durian, sublimation-dried strawberry, sublimation-dried coffee, and even various aerospace foods. But have you really understood sublimation drying? Not only can it preserve the form of the food, but it also retains most of the nutrients of the ingredients. Sublimation drying, is also named freeze-drying or lyophilization, will be discussed today.
Nowadays, we have mastered many food preservation techniques. Sublimation drying is one of the commonly used drying techniques and is regarded as the development direction of healthy food. What kind of food processing technology can keep the most original characters and flavors of food? Look at the banana, apple, and grape after sublimation drying and dehydration in the picture below. Which is closer to the original appearance of the fruit?
It is obvious that the left side remains the original appearance, and the sublimation-dried fruit is like sliced fruit. We should have known the miracle of sublimation drying, and then here comes the question: How to sublimation-dry food?
In a word, sublimation drying food is to cool the food containing water first, freeze it into a solid, and then sublimate the ice directly from the solid under vacuum state. Sublimation drying is a process of freezing → sublimation.
For food processing, the benefits of sublimation-drying are actually very obvious:
1. Thorough water control prevents the growth of microorganisms and extends the shelf-life;
2. During the sublimation process, the substance itself is frozen in the “ice shelf”, so that the dried products can maintain their original properties, and have ideal instant solubility and rapid rehydration;
3. Easily oxidized substances (such as vitamin C, etc.) can be effectively protected, and nutrition can be preserved intact;
4. Easy storage and transportation.
What kind of food can be sublimation dried?
In theory, almost all foods containing water can be sublimation dried (but for some foods with too much sugar, and foods with too low eutectic temperature, sublimation drying is not applicable). In addition to vegetables and fruits, this drying process also makes it easy to preserve dairy products and large pieces of food, etc.
Two categories of sublimation-dried foods
Foods after sublimation drying generally come in two categories, one does not require rehydration, and is more commonly found in sublimation-dried fruit pieces, sublimation-dried fresh milk or yogurt sugar.
The other kind requires for rehydration, and it is mostly found in sublimation-dried fungus powder, rice, porridge, vegetable wrap, etc.
Compared with foods that do not require rehydration, the processing of foods that require rehydration is more complicated. In order to avoid the tissue being punctured by the icing inside during sublimation drying, some auxiliary materials are often added to protect the cell tissue, such as salt, sugar, and milk powder.
Compared with traditional dried and puffed foods, sublimation-dried foods have better nutrition and physical properties. Compared with canned foods, sublimation-dried foods are easier to preserve, less prone to qualitative changes, and have much lower costs in transportation and storage. Sublimation drying has become the focus of many food companies.
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