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

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 kappa-carrageenan. After 2 h at pH 2.0/25 degrees C, B. adolescentis within the capsules prepared with genipin, alginate and kappa-carrageenan were significantly (p < 0.05) reduced from similar to 8.0-8.5 log CFU mL(-1) to 1.8, 4.6 and 3.6 log CPU mL(-1), corresponding to D-values of 4336 +/- 7.50 min, 25.75 +/- 0.47 min, and 32.23 +/- 1.28 min, respectively. The volume mean diameter of formed protein capsules prepared with genipin, alginate and kappa-carrageenan was 749.5 +/- 2.3 mu m, 21.9 +/- 1.2 mu m and 838.5 +/- 31.3 mu m, respectively. Capsules <100 mu m 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 2 h at pH 2.0/25 degrees C, the viable cell numbers (log CFU mL(-1)) decreased from similar to 8.0 to similar to 5.7 (D-value of 77.99 +/- 6.93 min), similar to 6.4 (D-value of 185.50 +/- 38.8 min) and similar to 4.6 (D-value of 4336 +/- 7.50 min) 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 pH 2.5/37 degrees C revealed that encapsulation with 10% of chickpea protein-0.1% of alginate improved survival by 5.5 times, with D-values of 10631 +/- 17.03 min (entrapped cells) versus 18.98 +/- 0.29 (free cells)) over 2 h. The release of encapsulated B. adolescentis within simulated intestinal fluid at pH 6.5/37 degrees C over 3 h indicated that after the first 5 min, almost all of the entrapped B. adolescentis (similar to 7.8 log CFU mL(-1)) cells were released, yielding free cell counts of similar to 7.1 log CPU mL(-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 (<100 mu m) and ability to protect acid-sensitive microorganisms under simulated gastric conditions. (C) 2013 Published by Elsevier Ltd.