Optimization of a green tea seed oil–loaded double‐layer emulsion and its preventive effects on dextran sulfate sodium–induced colitis in mice

Green tea seed oil (GTSO; Camellia sinensis) is rich in bioactive compounds and has great potential for preventing intestinal inflammation. Conversely, high-fat diets have been shown to promote or aggravate gastrointestinal inflammation, and the bioactive ingredients of GTSO face difficulty passing through the gastrointestinal tract while remaining intact. This study employed whey protein isolate (WPI) and sodium carboxymethyl cellulose (CMC-Na) to prepare a GTSO-loaded double-layer emulsion. The optimal parameters were as follows: WPI (2% w/w) and 35% oil phase for the primary emulsion preparation, CMC-Na (0.8% w/w) for the final emulsion, and 450 W of ultrasonic power for homogenization. No significant changes in particle size or coalescence in the emulsions were observed after 30 days of storage at 4°C. In addition, in a simulated gastrointestinal digestion system, more than 60% of the encapsulated GTSO was able to remain intact while passing through the gastric and small intestinal environment. In mice with dextran sulfate sodium-induced colitis, pretreatment with the GTSO emulsion significantly prevented the further development of colitis, whereas an empty-carrier-plus-free-GTSO treatment had no such protective effects and even tended to aggravate the disease. The results of the present study suggest that encapsulated GTSO is a reliable alternative approach for colitis prevention. PRACTICAL APPLICATION: The green tea seed oil-loaded double-layer emulsion demonstrates good storage stability when kept at 4°C, exhibits excellent slow-release performance, and achieves superior outcomes in the prevention of colitis. Our current study provides a reliable alternative approach for the prevention of colitis.