Freeze-drying is the process of dehydrating frozen foods under a vacuum so the moisture content changes directly from a solid to a gaseous form without having to undergo the intermediate liquid state through sublimation. In this process, the product maintains its original size and shape with a minimum of cell rupture. Removing moisture prevents a product from deteriorating at room temperature.

    The process is used for drying and preserving a number of food products, including meats, vegetables, fruits, and instant coffee products. The dried product will be the same size and shape as the original frozen material and will be found to have excellent stability and convenient reconstitution when placed in water. Freeze-dried products will maintain nutrients, color, flavor, and texture often indistinguisha-
ble from the original product.

    Depending on the product and the packaging environment, freeze-dried foods are shelf-stable at room temperature for up to ten years or more, if canned, and between 6 months to 3 years if stored in a poly-bag container. The main determinant of degradation is the amount and type of fat content and the degree to which oxygen is kept away from the product.