What Should You Know About Freeze Drying?
What food can be freeze dried?
What food can be freeze dried? Normally, any food can be freeze-dried. However, due to the high production cost, freeze-dried food only limits to those high-end ones. The food that can be applied to the tech can be roughly divided into the following categories:
1. Freeze-dried fruits and vegetables: such as pineapple, tomato, carrot, onion, garlic, apple, strawberry, peach, etc.
2. Freeze-dried poultry meat: such as pork, beef, chicken, rabbit meat, etc.
3. Freeze-dried aquatic products: such as shrimp, fish, sea cucumber, scallop, kelp, seaweed, etc.
4. Freeze-dried seasoning food: sauce, spices, etc.
5.Convenience food and others: such as aerospace food, junk food, tourist food, tea, coffee, etc.
How freeze drying works?
How freeze drying works? During freeze-drying, the food is frozen in the lyopgilization machine and the water in the food is removed by sublimation under certain conditions, which mainly includes two processes of freezing and sublimation.
It is not necessary to talk about freezing, since it is quite easy with no complicated concepts inside. But sublimation should be fully introduced.
Sublimation: The process (physical change) that a substance changes from a solid-state to a gaseous state without going through a liquid state due to a large temperature difference is called sublimation. Conditions: the continuous supply of heat and the continuous removal of generated water vapor.
How freeze drying works? Here are two concepts that need to mention during the sublimation process.
Eutectic point: For a solid mixed solution, when it reaches a certain temperature during the heating and melting process, a liquid state begins to appear in the solid. This temperature is called the eutectic point.
Collapse temperature of freeze-dried food: When the temperature is higher, the rigidity of the solid matrix of the honeycomb structure decreases. When the temperature reaches a certain critical value, the rigidity of the solid substrate is not enough to maintain the honeycomb structure, and the solid substrate wall of the cavity collapses. This critical temperature is called the collapse temperature of freeze-dried food.
What does freeze drying do to food?
What does freeze-drying do to food? Here are several effects:
(1) the Storage period
Freeze-dried food has been removed most of its water and generally, this food can be stored for 2 years at room temperature. If it is packaged in iron cans, it can be stored for a longer time.
The loss of volatile aromatic substances in freeze-dried food is significantly lower than the loss during hot air drying.
What does freeze drying do to food? Freeze drying may also slightly change the color. The product is less affected by oxygen, so there is less chance of browning and fading due to direct oxidation or enzymatic reaction of the food. Non-enzymatic browning of food may occur during freeze-drying, and the speed of browning mainly depends on the drying temperature and the remaining moisture in the food. In general, the color of freeze-dried food is better than that of products produced by other drying methods.
(4) Volume and mass
Dehydration presents a porous structure, and the tissue surface area is 100-150 times larger than the original. Therefore, the volume and mass of freeze-dried food are very small.
(5) Texture and taste
What does freeze drying do to food? After drying, the original structure of the food is destroyed and the taste changes. Water-soluble vitamins are lost more than the fat-soluble vitamin.
What food can be freeze dried? How freeze drying works? What does freeze drying do to food?
These are the things that you need to know about freeze drying. Hope you enjoy this share, and choose us as your supplier of freeze dryer and spray drying machine.