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Microencapsulated Lactobacillus rhamnosus GG Powders: Relationship of Powder Physical Properties to Probiotic Survival during Storage
Author(s) -
Ying Dan Yang,
Phoon Mei Chi,
Sanguansri Luz,
Weerakkody Rangika,
Burgar Iko,
Augustin Mary Ann
Publication year - 2010
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2010.01838.x
Subject(s) - lactobacillus rhamnosus , probiotic , food science , lactobacillus , chemistry , biology , bacteria , fermentation , genetics
Freeze‐dried commercial Lactobacillus rhamnosus GG (LGG) were encapsulated in an emulsion‐based formulation stabilized by whey protein and resistant starch and either spray‐dried or freeze‐dried to produce probiotic microcapsules. There was no difference in loss of probiotics viability after spray drying or freeze drying. Particle size, morphology, moisture sorption, and water mobility of the powder microcapsules were examined. Particle size analysis and scanning electron microscopy showed that spray‐dried LGG microcapsules (SDMC) were small spherical particles, whereas freeze‐dried LGG microcapsules (FDMC) were larger nonspherical particles. Moisture sorption isotherms obtained using dynamic vapor sorption showed a slightly higher water uptake in spray‐dried microcapsules. The effect of water mobility, as measured by nuclear magnetic resonance (NMR) spectroscopy, at various water activities ( a w 0.32, 0.57, and 0.70) and probiotic viability during storage at 25 °C was also examined. Increasing the relative humidity of the environment at which the samples were stored caused an increase in water mobility and the rate of loss in viability. The viability data during storage indicated that SDMC had better storage stability compared to FDMC. Although more water was adsorbed for spray‐dried than freeze‐dried microcapsules, water mobility was similar for corresponding storage conditions because there was a stronger water‐binding energy for spray‐dried microcapsule. This possibly accounted for the improved survival of probiotics in spray‐dried microcapsules. Practical Application: The mechanistic insights gained from this study using freeze‐dried probiotics can be applied during optimization of the microcapsule formulations and processing conditions for encapsulation and spray drying of fresh culture in a commercial application.