DEHYDRATION OF LACTOBACILLUS-ACIDOPHILUS

Freeze-drying, vacuum drying, and controlled low-temperature vacuum dehydration were used to dehydrate Lactobacillus acidophilus. The survival ratio from the freeze-drying treatment was found to be the highest. The survival ratio obtained from controlled low-temperature vacuum dehydration was close to that from freeze-drying and the drying time required could be much shorter. Controlled low-temperature vacuum dehydration, however, produced products with case hardening and shrinkage, and rehydration tended to be poor. The survival ratio from the vacuum-drying treatment was too low for the process to be applied in culture preservation. The addition of Ca2+ might increase the survival ratio after both freezing and freeze-drying. The application of various protective media (10 % NFDMS; 10 % NFDMS + 10 % sucrose + 0-5 % ascorbic acid + 0-5 % NH4Cl; 10 % NFDMS + 5 % glycerol) did not show any significant protective effect during the storage of the dehydrated products. Lower storage temperature led to better results during storage. Results of room-temperature storage were the worst, and those of the storage at 5-degrees-C and -20-degrees-C did not show any significant difference.