1977 年 26 巻 288 号 p. 823-826
The vacuum freeze drying by using zeolite as an adsorbent of water vapor was applied to food materials such as carrot and shrimp, and from the result of our experiment the following conclusions were drawn.
(1) The time needed for drying can be shortened substantially as compared with the conventional method, by circulating air current into the layered beds of food materials and zeolite.
(2) The dried products retain their original form and do not get stale during a long period of preservation (about two years).
(3) The zeolite which has adsorbed water vapor hardly desorbs under the pressure (10Torr∼0.4Torr) tried in this experiment, but easily desorbs when heated at about 500°C and can be used repeatedly.
(4) Natural zeolite was found to possess as much effectiveness as synthetic one. When economy is taken into account, the use of natural zeolite is highly recommendable.