Fabrication of Rubus chingii Hu ellagitannins-loaded W/O/W double emulsion gels stabilized by WPI/pectin complexes: Physicochemical properties, digestion characteristics, and transformation of ellagitannins

Ellagitannins (ETs) exhibit beneficial effects on gut microbiota modulation and bioactivity, but their instability compromises the delivery efficiency and absorption. Therefore, a double emulsion gel (DEG@RETs) loading with Rubus chingii Hu ETs (RETs) was constructed and optimized to enhance its gastrointestinal digestion stability and intestinal transformation. The optimal DEG@RETs formulation was 4 % pectin, calcium-induced gelation, W 1 /O: W 2 of 4: 6, and W 1 : O of 5: 5. Which achieved an encapsulation efficiency (EE) of 88.68 ± 4.36 %, maintained spherical structures with an EE (78.57 ± 1.34 %) after digestion. The DEG@RETs demonstrated pH and freeze-thaw stability while EE declined after heating at 90 °C. Cryo-SEM confirmed a crosslinked gel network. In vitro fermentation, transformation efficiency demonstrated significantly enhanced with urolithin A, urolithin B and ellagic acid increased by 7.37-, 3.19- and 7.87-fold respectively. These results proved that DEG@RETs can be an effective strategy to improve the colon-targeted delivery and biotransformation efficiency of RETs.