Pickering emulsions stabilized by soy protein/proanthocyanidins nanocomplexes: Physicochemical properties and in vitro release properties

As a class of natural antioxidant polyphenols, proanthocyanidins (PANs) offer unique advantages in anti-inflammatory, anti-tumor, and anti-cancer fields. However, the practical application of PANs is hindered by their low stability and limited bioavailability. Pickering emulsions have shown great potential in addressing the issue of PANs' susceptibility to degradation, with their stability mainly dependent on stabilizers. In recent years, soy proteins have gained significant attention as stabilizers for Pickering emulsions due to their excellent biocompatibility and amphiphilicity. In this work, we integrated soy protein isolate (SPI) with PANs to create SPI-PANs nanocomplexes serving as stabilizers for Pickering emulsions, aiming to enhance emulsion stability and safeguard PANs from environmental degradation. Our findings indicated that SPI-PANs nanocomplexes with a 50:4 mass ratio of SPI and PANs demonstrated outstanding antioxidant capacity, low hydrophobicity, and relatively small, uniform particle sizes. The non-covalent interactions between SPI and PANs primarily involved hydrophobic interactions and hydrogen bonds. Subsequently, we successfully prepared oil-in-water SPI-PANs Pickering emulsions using homogenization techniques. Our in vitro digestion and release studies revealed that these emulsions exhibited nearly double the PANs retention compared to controls (pure PANs), highlighting their significant sustained-release advantage. Additionally, the emulsions demonstrated significant creaming stability and were non-cytotoxic to HEK 293 T and HeLa cells. Overall, SPI Pickering emulsions remain considerable potential as a carrier system for the intestinal delivery of PANs and other bio-functional compounds in the field of functional food.