PURPOSE: To prepare dried mushroom having the original taste and flavor of raw mushroom without causing the decomposition of nutrients during preparation process by subjecting water-washed mushroom to instantaneous freezing, instantaneous high-pressure sterilization and vacuum freeze-drying.

CONSTITUTION: Mushroom is washed with water and inspected and classified by the aid of optical sensor, laser, sieving, etc. The selected mushroom is washed with aseptic water and subjected to instantaneous freezing and instantaneous high-temperature sterilization. The sterilized mushroom is freeze-dried in vacuum. The dried mushroom prepared by the present process can be reconstituted to the original shape within about 2-3min when thrown into water.