Dehydration of Lactobacillus acidophilus

Accelerated storage testing of freeze-dried and controlled low-temperature vacuum dehydrated Lactobacillus acidophilus.

“…The culture might be mixed with some protectants in order to improve survival during the drying process (Potts, 1994). Controlled low-temperature vacuum dehydration (CLTVD), a newly developed drying method, was used to dehydrate the strain in order to avert some defects of freeze-drying, and products with quality close to those of freeze-drying could be obtained (King and Lin, 1995;King and Su, 1993). The application of CLTVD not only reduced the drying time and cost but also avoided freeze-injury to the cells (King and Su, 1993).…”

“…Controlled low-temperature vacuum dehydration (CLTVD), a newly developed drying method, was used to dehydrate the strain in order to avert some defects of freeze-drying, and products with quality close to those of freeze-drying could be obtained (King and Lin, 1995;King and Su, 1993). The application of CLTVD not only reduced the drying time and cost but also avoided freeze-injury to the cells (King and Su, 1993). The combination of adding CaCO 3 , glycerol, and nonfat dry milk solids (NFDMS) as protectants had also been studied in CLTVD and freeze-drying for the amelioration of survival during the drying of cultures (King and Lin, 1995).…”

“…The cell pellets were then suspended in 10 ml protective media to make concentrated cell suspensions of about 10 9 -10 10 cells/ml for the experiments. Three different protective media were used for experiments: (1) 10% NFDMS was used as the basal medium for drying without protectants (Bozoglu and Gurakan, 1989;King and Su, 1993), (2) 4.15% glycerol and 10.08% NFDMS for freeze-drying, and (3) 4.10% glycerol and 10.71% NFDMS for CLTVD with protectants based on the optimum conditions obtained by King and Lin (1995).…”

“…Referring to the method of King and Su (1993), samples with and without protectants were frozen at Ϫ40°C overnight in an ultra-low temperature freezer before freeze-drying, and freeze-drying was conducted at a system temperature of around Ϫ60°C and at a pressure below 1 mmHg in a freeze-dryer (Eyela Model 540-FDU, Tokyo Rika, Inc., Tokyo, Japan) until a moisture content of approximately 3% w/w was reached. For CLTVD, temperatures passing the zone of maximum ice crystal formation in tested samples were monitored using an automatic time-temperature recorder (Model HR 1300, Yokogawa Electric Corp., Tokyo, Japan).…”

“…This might be due to the higher ratio of injured cells obtained after drying for CLTVD as compared to freeze-drying on the account of a higher operating temperature and the evaporation-drying mechanism of CLTVD. However, freeze-injury was avoided and drying time shortened (King and Su, 1993), and the application of protectants seemed to improve survival during storage. The thermal death of freeze-dried and CLTVD suspensions of L. acidophilus could be treated as a first-order reaction (Toledo, 1991);…”