EVIDENCE OF MEMBRANE DAMAGE IN LACTOBACILLUS-BULGARICUS FOLLOWING FREEZE-DRYING

The mechanism of inactivation of Lactobacillus bulgaricus due to freez e drying was investigated. Cells were freeze-dried in skim milk powder , maltodextrin, glycerol, trehalose and water. Results are presented c onfirming previous authors' observations regarding membrane damage dur ing freeze drying. In an attempt to define more clearly the nature of this damage, further experiments were carried out. Results show that f ollowing freeze drying changes occur in the unsaturated : saturated fa tty acid ratio, a decrease in the activity of the membrane-bound enzym e ATPase and a loss of Delta pH.