Vacuum FD technology refers to the technique by which icy water in frozen food is directly changed to a vapor state without melting to water. As the FD food is dehydrated at very low temperature, few nutrition constituents and flavoring matters in the food is lost, and the original nutritional flavor is retained to a maximum. Quick water recovery from several seconds to minutes results in substantial or full similarity to the fresh food in color, flavor, taste and appearance. Thorough dehydration and light weight are especially suitable for long-distance transportation and field operation. It boasts a long storage period and can be kept at room temperature for three, five, even up to ten years.

    In the production of vacuum FD food, such processes as selection of raw materials, rinsing, splitting, kiering and sterilization are indispensable. Insects, eggs and mud deposited on the rhizome should be eliminated, metal impurity removed in the magnetic field and foreign matter like hair and scale cleared off by static electricity. Overheating should be avoided. Either boiling or dipping should be done to the process requirement. Only by doing a good job of preliminary treatment can high-quality FD food be made. The preliminary processed food should be frozen quickly. The quicker it is frozen, the smaller the crystal in the food will become and the lesser the structure will be destructed. Because of shorter freezing time, the protein won’t be deteriorated under the action of condensation and concentration.

    The quick-frozen food must be dried quickly through sublimation in vacuum, which requires that vacuum reach sublimation pressure soon. Sublimation temperature should be kept constant by supplying sublimation heat in time, through radiation heating usually. The FD food is porous with surface structure larger than the original by 100-150 fold, hence more chance to contact oxygen. Restoration from low temperature and pressure to normal pressure should be effected in nitrogen atmosphere. Crushing and packing should be completed at a relative humidity of 30%-40% and a temperature of 25C0 and below. To keep the FD food with a water content of less than 5%, desiccant should be placed in the package to absorb trace water. The packing material should have poor air permeability, high strength and dark color.

    1.Features and Application of Vacuum FD Food

    Vacuum FD dehydrated food is briefly referred to as “FD Food”. It is made by use of the most advanced process of preserving food in the world-vacuum FD technique, by which fresh food (vegetable, meat, sea food and fungus) is made into dehydrated products by freezing water into ice quickly, heating, subliming in vacuum and drying. As drying is effected at a low temperature in vacuum, FD food enjoys incomparable advantages to food made by other methods

    (1)Flavor, color, taste and nutrition constituents of fresh food are retained to a maximum;

    (2)Appearance of fresh food remains unchanged;

    (3)Good water recovery-the state of fresh food can be recovered in a short time;

    (4)Natural healthy food without any additives;

    (5)Good storage. It can be stored at room temperature for more than one year without the need of refrigeration;

    (6)Light weight facilitates transportation.

    2.As a high-grade dehydrated food, vacuum FD food has been favored gradually by people from all walks of life:

    (1)Convenience food sector

    High-grade instant noodle, instant rice, instant rice flour etc. are high prized and in great demand since the FD products (vacuum frozen dehydrated meat, sea food and vegetable) are added, which are famous for its perfect combination of color, flavor and taste in addition to good water recovery.

    (2)Soup material processing sector

    In the ever-increasing quick rhythm of city life, because of the advent of FD soup material package, it is no more a dream to enjoy a bowl of delicious, nutritive and pleasant soup.

    (3)Instant drink sector

    Vacuum FD instant coffee, instant tea and instant juice have claimed top excellence in the instant drink sector by its high quality and grade.

    (4)Nutritional health food and beauty treatment sector

    In the family of health food, high-grade food like vacuum FD turtle meal, snake bile meal, black-boned chicken meal, queen bee jelly meal and yak penis capsule has a ready market. Beside, FD sheep placenta meal and FD aloe meal have become favorites in the beauty circle.

    (5)Special sectors