W/O/W emulsions with gelled aqueous and oil phases: Construction, characterization, and their effect on enhancing the stress resistance of Lactobacillus plantarum and Streptococcus thermophilus.

Abstract

To overcome the poor stability and low probiotic survival associated with traditional delivery systems, this study systematically developed and compared water-in-oil-in-water (W/O/W) emulsions with different phase gelation strategies. Three emulsion types were constructed: oil-phase (O-W/O/W), external aqueous-phase (A-W/O/W), and dual-phase gelled (B-W/O/W) emulsions. The results revealed that dual-phase gelation (B-W/O/W) exhibited a superior synergistic effect compared to single-phase gelation. Both aqueous- and oil-phase gelation increased apparent viscosity and restricted internal water mobility, but their combination provided the most robust physical barrier. Specifically, oil-phase gelation reduced particle size by immobilizing free water, while aqueous gelation formed a dense protective network. This synergistic protection significantly enhanced probiotic viability during pasteurization, in vitro digestion, and long-term storage. This study demonstrates that dual-phase gelation is a highly effective and novel strategy for the development of high-performance delivery vehicles, providing a theoretical basis for the commercial application of sensitive probiotics in functional foods.