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Entrapment, survival and release of Bifidobacterium adolescentis within chickpea protein-based microcapsules

Wang, Jiapei, Korber, Darren R., Low, Nicholas H., Nickerson, Michael T.
Food research international 2014 v.55 pp. 20-27
Bifidobacterium adolescentis, cell viability, chickpeas, crosslinking, emulsions, encapsulation, gastric juice, gastrointestinal system, kappa carrageenan, probiotics, protein isolates, sensory properties
Bifidobacterium adolescentis (ATCC 15703) was entrapped within microcapsules prepared using 10.00% (w/w) chickpea protein isolates cross-linked with 0.20% (w/v) of genipin, or in the presence of 0.20% (w/v) alginate or κ-carrageenan. After 2h at pH2.0/25°C, B. adolescentis within the capsules prepared with genipin, alginate and κ-carrageenan were significantly (p<0.05) reduced from ~8.0–8.5logCFUmL−1 to 1.8, 4.6 and 3.6logCFUmL−1, corresponding to D-values of 43.36±7.50min, 25.75±0.47min, and 32.23±1.28min, respectively. The volume mean diameter of formed protein capsules prepared with genipin, alginate and κ-carrageenan was 749.5±2.3μm, 21.9±1.2μm and 838.5±31.3μm, respectively. Capsules <100μm in diameter do not adversely affect sensory attributes, therefore only the chickpea protein–alginate design was tested further. The effect of alginate concentration (0.05, 0.10 and 0.20%, w/w) added to chickpea protein capsules were investigated for their ability to protect B. adolescentis. After 2h at pH2.0/25°C, the viable cell numbers (logCFUmL−1) decreased from ~8.0 to ~5.7 (D-value of 77.99±6.93min), ~6.4 (D-value of 185.50±38.8min) and ~4.6 (D-value of 43.36±7.50min) for chickpea protein with capsules with 0.05%, 0.10% and 0.20% (w/w) alginate, respectively. The number of surviving free and entrapped B. adolescentis cells after incubation in synthetic gastric juice at pH2.5/37°C revealed that encapsulation with 10% of chickpea protein–0.1% of alginate improved survival by 5.5 times, with D-values of 106.31±17.03min (entrapped cells) versus 18.98±0.29 (free cells)) over 2h. The release of encapsulated B. adolescentis within simulated intestinal fluid at pH6.5⁄37°C over 3h indicated that after the first 5min, almost all of the entrapped B. adolescentis (~7.8logCFUmL−1) cells were released, yielding free cell counts of ~7.1logCFUmL−1, followed by no further release. Encapsulation of B. adolescentis within chickpea protein–alginate microcapsules using emulsion technology allows probiotics to be protected against a simulated gastrointestinal environment, indicating their potential use in food and/or medical applications. Findings from this study suggest that chickpea protein–alginate capsule designs could serve as a suitable probiotic carrier intended for food applications due to its size (<100μm) and ability to protect acid-sensitive microorganisms under simulated gastric conditions.