Study on the Preparation of W/O/W Emulsion Based on Three Polysaccharides Mixed with Casein and Its Encapsulation Effect of Salidroside

To improve the stability and oral absorption effect of salidroside, W/O/W multiple emulsion was prepared with salidroside as the internal aqueous phase and rapeseed oil containing polyglycerol polyricinoleate as the oil phase, and dextran, chitosan and soybean polysaccharide mixed casein as the external aqueous phase. The effects of three polysaccharides with different concentrations on the microstructure, particle size, potential, storage stability, surface hydrophobicity, emulsifying property, embedding rate, drug loading, and in vitro digestion of multiple emulsions were studied. The results showed that compared with the casein control group, chitosan-casein group, and soybean polysaccharide-casein group, dextran-casein W/O/W multiple emulsion had the best stability. A high concentration of dextran could significantly improve the storage stability of dextran-casein multiple emulsions. When the addition of dextran was 1.2%, the average particle size of the multiple emulsions was the smallest, up to 623.03±5.21 nm (P<0.05). The absolute value of potential was the highest (P<0.05), and the average potential was −37.3±0.46 mV. The emulsifying property of casein was improved the most (P<0.05). The embedding rate of salidroside was the highest (P<0.05), up to 92.8%, and the drug loading was 162.89±4.21 μg/g. The study of simulated digestion showed that the dextran-casein multiple emulsion could not only effectively protect the salidroside, but also target the delivery and release in the simulated intestine. The dextran-casein loading system with the addition of 1.2% dextran had the best stability and controlled release effect. The research results can provide theoretical support for the application of salidroside in both food and medicine.