Biomacromolecule based water-in-water Pickering emulsion: A fascinating artificial cell-like compartment for the encapsulation of Lactobacillus plantarum

Probiotics are considered to have the potential to be beneficial to health when consumed in adequate amounts. Maintaining excellent probiotic activity during food storage and gastrointestinal transport is a key challenge. In this study, a stable water-in-water (W/W) Pickering emulsion consisting of hydroxypropyl methylcellulose (HPMC) and dextran (DEX) was constructed. Cellulose nanocrystals (CNCs) were used as the solid stabilizers of the emulsion. The obtained emulsions had excellent long-term stability with no phase separation within 60 days. In addition, the pH and ionic strength had little influence on the stability performance of the emulsions. The W/ W Pickering emulsion system was applied to the probiotic encapsulation, and the emulsion was micro-encapsulated by spray drying technique. The microscopy images showed that Lactobacillus plantarum tended to be enriched in the dispersed phase of W/W Pickering emulsions. The viable cell content of obtained micro -capsules was 2.22 x 1010 CFU/g after spray drying. Furthermore, the viable cell content in emulsion micro -capsules was 3.38 x 106 CFU/g after the simulated digestion process in artificial gastrointestinal fluid. The microcapsules containing Lactobacillus plantarum also showed excellent stability during the storage. The viable cell content of microcapsules was 1.76 x 109 CFU/g at 4 degrees C after 90 days of storage. This study could provide a potential method by using W/W Pickering emulsion as a system for encapsulating probiotics, which would provide protection for probiotics during spray drying and gastrointestinal digestion.