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A water-in-oil-in-water (W/O/W) emulsion for the encapsulation of salidroside (Sal) was constructed. This study aimed to detect the impact of whey protein isolate (WPI) on the microstructure and stability of Sal W/O/W emulsion, which was prepared by two-step emulsification. First, Sal and sodium alginate (SA) were added to the inner water phase, and polyglycerol polyricinoleate (PGPR) was added to the oil phase to prepare a water-in-oil (W/O) emulsion. Second, different concentrations of WPI were added to the outer water phase containing SA to prepare a Sal W/O/W emulsion. The microstructure, stability, moisture distribution, rheological properties, and encapsulation efficiency of Sal were detected. The results showed that the particle size and the size distribution range became smaller and narrower with increasing WPI concentration. When the concentration of WPI was greater than 2%, the double-layer structure remained stable over 28 days of storage at 4 °C. Moreover, when the WPI concentration reached 4%, the entrapment efficiency of Sal was the highest. These results indicated that the optimum concentration of WPI was 4%. [Display omitted] • The salidroside (Sal) W/O/W emulsions were stabilized by whey protein isolate (WPI). • WPI significantly decreased the emulsion particle size. • The encapsulation efficiency of Sal reached 77.9 ± 1.3% by 4% WPI. • WPI densified the microstructure of Sal W/O/W emulsion. [ABSTRACT FROM AUTHOR]

In this study, cold-set large yellow croaker (Pseudosciaena crocea) roe protein isolate (pcRPI) gels were prepared by glucono-δ-lactone (GDL) at different concentrations. The 0.1% and 0.2% GDL induced pcRPI at 50 mg/mL to form cold-set gels, while pcRPI suspension with 0.4% GDL addition still showed a fluid state. The pcRPI gel induced by 0.2% GDL showed better rheological properties and its G' value was about 5.1 times than that of 0.1% GDL. In addition, pcRPI gels induced by 0.1% and 0.2% GDL showed similar water holding capacity, and 0.2% GDL-induced pcRPI gels showed a special T 2 peak in 2249.0 ms which might represent free water on the surface of the gel. Furthermore, the higher total number of junctions, vessels percentage area, and lower lacunarity indicated a denser three-dimensional network structure in pcRPI gels induced by 0.1% and 0.2% GDL. Particle size tests and AFM results further confirmed that GDL induced pcRPI to form cold-set gels by promoting the formation of protein aggregates. Therefore, 0.1–0.2% GDL are suitable to prepare pcRPI cold-set gels. These results may deepen the understanding on cold-set pcRPI gels induced by GDL. • Pseudosciaena crocea roe protein isolates (pcRPI) had potential to form cold-set gels. • 0.2% glucono-δ-lactone (GDL)-induced pcRPI gels showed good rheological properties. • The 0.1–0.2% GDL induced pcRPI gels had a dense three-dimensional network structure. • GDL-induced pcRPI gels were promoted by the formation of protein aggregates. [ABSTRACT FROM AUTHOR]