freeze dried的意思|示意

Freeze drying（细胞冻干）, also known as lyophilization, is a process used to preserve perishable materials, especially food and biological samples. It involves freezing the material, then reducing the surrounding pressure and adding heat to allow the frozen water in the material to sublimate directly from the solid phase to the gas phase. Freeze drying is a popular method for preserving food because it prevents the growth of microorganisms and does not require the addition of preservatives, a practice that can sometimes result in a loss of flavor.

Freeze-dried food is made by first freezing the food and then putting the frozen food in a vacuum chamber. This vacuum environment creates a \"cold, dry air\" atmosphere where temperatures remain below freezing while the air pressure is reduced. As the air pressure is reduced, the ice in the food will begin to vaporize, allowing the food to reach a semi-solid state. Once the vacuum is released and the food is exposed to atmospheric pressure, the food will quickly transition to a solid state.

The freeze-dried food can then be packaged in airtight containers or bags, allowing it to retain its original flavor, texture, and nutritional value for months or even years. Freeze-dried food is typically much lighter than regular food, so it is easy to transport. It also requires minimal preparation, since it does not need to be refrigerated or cooked.

Freeze-dried food is often used for long-term food storage, space exploration, military operations, and backpacking. It is also used by athletes, hikers, and campers who need a lightweight and nutritious food source. Freeze-dried food is an excellent addition to any type of emergency preparedness kit, since it can be easily stored and used in the event of an emergency.