Enhancing antioxidant capacity of chitosan‐caseinophosphopeptides nanocomplexes‐stabilized Pickering emulsion by incorporating theaflavin‐3,3′‐digallate

BACKGROUND: Emulsions are common colloidal systems in food products, yet their quality is frequently compromised by lipid oxidation. We have recently developed a new Pickering emulsion stabilized by genipin cross-linked chitosan-caseinophosphopeptides nanocomplexes (GCNs). However, this system remains susceptible to oxidative deterioration, which may adversely affect both product quality and emulsion stability. In this study, a natural antioxidant, theaflavin-3,3'-digallate (TF-3), was encapsulated within GCNs to improve oxidative protection. RESULTS: Incorporation of TF-3 did not significantly alter the surface charge but increased the size of GCNs. The TF-3-loaded GCNs effectively stabilized oil-in-water type Pickering emulsions with gel-like rheological properties, and TF-3 further strengthened the gel network. These Pickering emulsions exhibited markedly enhanced oxidative stability compared to the oil-water physical mixture and a conventional emulsion during long-term storage at 40°C, as evidenced by reduced formation of both primary and secondary oxidation products. The extent of oxidative protection was concentration-dependent, with higher TF-3 loadings leading to lower levels of oxidation products. Moreover, TF-3 localized at the oil-water interface demonstrated superior antioxidant efficacy relative to its distribution in either the oil phase or water phase, highlighting the critical role of interfacial localization in maximizing oxidative stability in Pickering emulsion systems. CONCLUSION: In conclusion, TF-3-loaded GCNs effectively stabilized food-grade oil-in-water Pickering emulsions with gel-like networks and concentration-dependent oxidative protection. Importantly, interfacial localization of TF-3 maximized its antioxidant efficacy, highlighting interfacial engineering as a promising strategy for designing oxidation-resistant Pickering emulsion systems.