Encapsulation of Lactobacillus casei ATCC 393 cells and evaluation of their survival after freeze-drying, storage and under gastrointestinal conditions

The aim of this work was to investigate the encapsulation of Lactobacillus casei ATCC 393 cells with a pea protein isolate-alginate hydrogel matrix and to study the protective effects of such matrix on the bacteria during freeze-drying, storage and under harsh gastrointestinal conditions. The encapsulation of L. casei achieved a high yield of 85.69% ± 4.82 which indicated that the matrix and the encapsulation technique are compatible with the probiotic strain. During the freeze-drying process, the matrix did not show any protective effect as compared to the non-encapsulated cells. The dried capsules have been taken into subsequent storage tests at three temperatures (+22, +4 and −15 °C). After 84 days of storage, the encapsulated L. casei stored at −15 °C showed the highest survival rate among all samples (59.9% ± 17.4). After 84 days of storage, the capsules stored at −15 °C were submitted to further survival and release tests in simulated gastrointestinal fluids. These dried and stored capsules displayed a weaker buffering effect against acidic gastric conditions as compared to the fresh capsules which were tested right after the encapsulation. However, both stored and fresh capsules showed similar release profiles of L. casei in simulated intestinal fluid.