Microencapsulation of probiotic bacteria using pH-induced gelation of sodium caseinate and gellan gum

A sodium caseinate and gellan gum mixture was gelled by gradually decreasing pH with glucono-delta-lactone (GDL). Lactobacillus casei cells were successfully entrapped into this gel matrix by a water-in-oil emulsion. The optimum ingredient combination, based on elastic modulus and relative gelation time to attain adequate gel strength, was 10% (w/w) sodium caseinate, 0.25% (w/w) gellan gum and 2.5% (w/w) GDL. A very fine, uniform capsule particle size distribution resulted. The surface-weighted and volume-weighted mean capsule diameters were about 287 and 399 mu m, respectively. The ratio of the core bacteria to the wall ingredients was optimized to achieve a high encapsulation yield of similar to 89.5%. The survival of encapsulated cells after 30 min of incubation in simulated gastric fluid was significantly (P < 0.001) greater than that of free cells, both with and without the addition of pepsin. The capsules also provided significant protection for L. casei against detrimental bile salts. (C) 2010 Elsevier Ltd. All rights reserved.