Enhancement of cell stability and viability of probiotic Leuconostoc mesenteroidesMTCC 5209 on freeze drying

Co-encapsulation of probiotics with acylglycerols in gelatin-gum arabic complex coacervates: Stability evaluation under adverse conditions

Co-encapsulation of acylglycerols and probiotics may improve the resistance of probiotics to adverse conditions. In this study, three probiotic microcapsule models were constructed using gelatin (GE)-gum arabic (GA) complex coacervate as wall material: microcapsules containing only probiotics (GE-GA), microcapsules containing triacylglycerol (TAG) oil and probiotics (GE-T-GA) and microcapsules containing diacylglycerol (DAG) oil and probiotics (GE-D-GA). The protective effects of three microcapsules on probiotic cells under environmental stresses (freeze-drying, heat treatment, simulated digestive fluid and storage) were evaluated. The results of cell membrane fatty acid composition and Fourier transform infrared (FTIR) spectroscopy revealed that GE-D-GA could improve the fluidity of cell membrane, maintain the stability of protein and nucleic acid structure, and decrease the damage of cell membrane. These characteristics supported the high freeze-dried survival rate (96.24 %) of GE-D-GA. Furthermore, regardless of thermotolerance or storage, GE-D-GA showed the best cell viability retention. More importantly, GE-D-GA provided the best protection for probiotics under simulated gastrointestinal conditions, as the presence of DAG reduced cell damage during freeze-drying and the degree of contact between probiotics and digestive fluids. Therefore, co-microencapsulation of DAG oil and probiotics is a promising strategy to resist adverse conditions.

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 1.20 × 10-2 and 5.79 × 10-2 1/day during subsequent storage at 4 °C for 180 days and 30 °C for 90 days, respectively. Glass transition temperatures (T g) of freeze-dried probiotic in various protectants were 14.2-25.4 and 42.9-50.1 °C after storage at 4 and 30 °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.