Abstract: This study aimed to develop stable Wgel/O/W2 multiple emulsions for the high-efficiency co-encapsulation of the hydrophilic vitamin (VC) and lipophilic vitamin (VE) through a synergistic strategy of inner-phase gelation and interface component optimization. The effects of polyglycerol polyricinoleate (PGPR) concentration and water-to-oil ratio on the properties of the primary W1/O emulsion were systematically investigated. Subsequently, the W1/O/W2 emulsion was successfully constructed using a maltodextrin-whey protein isolate (MD-WPI) complex as the external hydrophilic emulsifier. Results indicated that under optimal conditions (5% PGPR, 3:7 water-to-oil ratio, 20% MD-WPI, and a 2:8 primary emulsion ratio), the emulsions exhibited a highly uniform particle size distribution. Notably, the incorporation of 2% gelatin into the inner aqueous phase significantly enhanced structural mechanical strength of droplets in the Wgel/O/W2 emulsion, effectively inhibiting the coalescence and swelling of internal droplets. This led to exceptionally high encapsulation efficiencies of 98.28% for VC and 93.29% for VE. This work not only provides an effective strategy for overcoming the instability of multiple emulsions but also offers valuable theoretical insights for the design of efficient co-delivery systems for functional ingredients with varying polarities.

Key words: multiple emulsion; gelatin; co-encapsulation; vitamin C; vitamin E