Bioactivity of proanthocyanidin-whey protein isolate stabilized Pickering emulsion with encapsulated β-carotene

β-carotene (BC) has many important physiological functions but is limited in functional food applications due to low stability and bioavailability. This study developed a Pickering emulsion delivery system stabilized by whey protein isolate (WPI) and proanthocyanidins (PC) with different polymerization degrees to encapsulate β-carotene. Compared to WPI, the incorporation of PC significantly increased the UV stability and encapsulation efficiency of BC. In vitro simulated digestion indicated that the WPI-oligomeric PC complex formed a more stable emulsion, reduced lipid hydrolysis, and enabled sustained release of BC. IEC-6 cell experiments demonstrated that the BC-loaded Pickering emulsions had significantly increased cell viability, lowered intracellular reactive oxygen species (ROS), and regulated cellular nitric oxide (NO) production. Notably, emulsions stabilized with oligomeric PC exhibited superior antioxidant and cell protection compared to polymeric PC. These findings provide a promising strategy for developing protein-polyphenol-based Pickering emulsions as effective carriers for lipophilic bioactive compounds in functional food applications.