The Stability and Gastrointestinal Digestion Characteristics of Natural Walnut Oil Body Emulsion

To understand the stability and gastrointestinal digestion characteristics of the natural walnut oil bodies (OBs) emulsion, walnut OBs were extracted from fresh walnuts and dispersed in aqueous phase to form O/W natural emulsions. The results showed that the natural walnut OBs emulsion droplets were uniformly dispersed in the aqueous phase as spherical particles, with triglycerides in the core and proteins surrounding them. SDS-PAGE indicated that the molecular weight of these proteins was below 55 kDa. The natural walnut OBs emulsion exhibited unstable at pH 4.0 and 6.0. Within the salt ion concentration range of 0-500 mM, the natural walnut OBs emulsion exhibited stable. Within the heat treatment temperature range of 0-85°C, the natural walnut OBs emulsion presented stable, but the droplets of the natural walnut OBs emulsion showed obvious aggregation at 95°C and became unstable. During the 0-120 min gastric digestion process, the droplets of the natural walnut OBs emulsion showed obvious aggregation and oil-water phases separation, and the particle size significantly increased with the extension of digestion time. During the 0-120 min small intestinal digestion stage, as the digestion time increased, the droplet size and the number of droplets decreased, while the release of free fatty acids continuously increased. This study lays a foundation for the application of walnut OBs in the food industry and the delivery of liposoluble bioactive substances.