Enhanced viability of Lactiplantibacillus plantarun by encapsulation with whey protein isolate fibrils and polysaccharides through layer-by-layer coating

The heat-induced whey protein isolate fibrils (WPIF) were interacted with carrageenan (CG), hyaluronic acid (HA) or inulin through layer-by-layer (LbL) coating to protect probiotics from processing conditions and harsh gastrointestinal environment. Results showed that the LbL coating was mainly driven by the forces of electrostatic interactions and hydrogen bonding formed between the hydroxyl or carboxyl groups of polysaccharides or amino groups in WPIF. Compared with the uncoated ones, the LbL-coated L. plantarun90 showed enhanced stability, hydrophobicity and self-cohesive and cell adhesion capacity. The highest survival rate of coated (WPIF/ CG)1.5-L. plantarun90 reached 90.16% after freeze-drying, while (WPIF/CG)2.5-L. plantarun90 showed a high survival rate of 84.34% at low pH3.0. The coated L. plantarun90 had an above 60% remaining under harsh acid, bile salt and simulated gastrointestinal conditions. Moreover, they showed improved hydrophobicity and self- cohesive, cell adhesion capacity to Caco-2 cells, of which (WPIF/HA)1.5-L. plantarun90 displayed the high self- cohesive force of 95.57%, and its adhesion number to Caco-2 cells reached about 67.78 CFU/cell, 8.5-fold of the uncoated L. plantarun90, indicating excellent adhesion properties. This LbL strategy had a great potential application in protecting and delivering probiotics to the targeted sites.