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-δ-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 μm, respectively. The ratio of the core bacteria to the wall ingredients was optimized to achieve a high encapsulation yield of ∼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.