Impact of protectants on the storage stability of freeze-dried probiotic Lactobacillus plantarum

The ability of rice protein supplemented with various prebiotics to protect probiotic Lactobacillus plantarum TISTR 2075 upon freeze-drying and subsequent storage was determined. A combination of rice protein-fructooligosaccharide (RF) provided the best storage stability with the lowest specific rate of cell death (k) of 1.20x10(-2) and 5.79x10(-2)1/day during subsequent storage at 4 degrees C for 180days and 30 degrees C for 90days, respectively. Glass transition temperatures (T-g) of freeze-dried probiotic in various protectants were 14.2-25.4 and 42.9-50.1 degrees C after storage at 4 and 30 degrees C, respectively. The functional properties of freeze-dried probiotic with protectants remained stable. The presence of RF could effectively protect and enhance the probiotic functionality during exposure to gastrointestinal tract conditions. The pathogenic inhibition of freeze-dried probiotic against foodborne pathogens was not different from the active cells. Protective agents were able to maintain high degrees of cell surface hydrophobicity.