THE EFFECT OF DIFFERENT HEATING PATTERNS ON VACUUM FREEZE-DRYING OF LITCHI PULPjfpe_

摘要

Three heating patterns, constant temperature, temperature programmed and programmedncooling process were applied to freeze-drying (FD) the litchi pulp in ordernto obtain the optimalFDheating technology.The results showthat the three patternsnall could be used to FD litchi pulp while the appearance was maintained well. Thendrying time of FD litchi pulp using programmed cooling process was the shortestnamong the three optimal heating patterns and the drying time was reduced by 15.8nand 11.6% comparing that of FD using constant temperature and temperature programmed.nHigher temperature can be applied at the early primary drying stagewhennthe temperature of litchi pulp is under the eutectic temperature and at secondaryndrying stage but should not be used at the later primary drying stage.