CHANGES IN VOLATILE COMPOUNDS OF COOKED BEEF DURING FREEZE DRYING

摘要

IntroductionFreeze-drying is a dehydration process in which water is removed by sublimation of ice from frozen materials. As ice sublimes, the sublimation interface, which starts at the outside surface of the material recedes, and a porous shell of dried material remains. Vapourized water is transported through the porous layer of the dried material. Freeze-drying, although expensive, is the best method for drying foods with regards to its quality. Preservation of most of the initial raw material properties such as shape, appearance, taste, colour, flavour, texture, biological activity etc. makes it one of the best drying methods. The product also maintains its initial shape and dimensions (James P. George, et al, 2002)