Anthocyanin-loaded CNC–whey protein complexes: Interfacial stabilization and oxidative challenges in Pickering emulsions

A novel stabilizer comprising anthocyanin (AN)-incorporated cherry stalk cellulose nanocrystals (CS-CNCs)/whey protein (WP) complex was developed to stabilize O/W Pickering emulsions (PEs) with improved physical and lipid oxidation stability during storage. Preparing CS-CNC/WP complexes with three mass ratios (1:1, 1:2, and 1:4) at different pH levels showed that pH 4 was optimal for complex formation. Compared to native CS-CNCs, the CS-CNC/WP complexes had significantly larger particle sizes and lower zeta potential. Fourier-transform infrared (FTIR) spectroscopy revealed characteristic shifts in amide I and II bands, while fluorescence quenching of tryptophan residues indicated strong non-covalent interactions, confirming the complexation between CS-CNC and WP. Although all CS-CNC/WP complexes showed higher contact angles (CAs) than CS-CNCs alone, the CS-CNC/WP (1:4) complex (CA = 50.9°) was selected for its enhanced hydrophobicity and potential interfacial activity. Incorporation of AN from cherry pomace waste significantly enhanced the antioxidant activity of the optimal complex, slightly reduced its contact angle (45.85°), and reinforced complex formation through stronger non-covalent interactions as indicated by amide band shifts and enhanced tryptophan quenching. Unlike the unstable PEs prepared using CS-CNC or WP alone, those stabilized with CS-CNC/WP and AN-loaded CS-CNC/WP complexes showed remarkable physical stability, with smaller, more uniformly distributed droplets. The chemical stability analysis by monitoring primary lipid oxidation products revealed that AN unexpectedly acted as a prooxidant in CS-CNC/WP/AN-stabilized emulsions, accelerating lipid oxidation over 28 days. • High-recovery valorization of cherry waste for CNC and anthocyanin (AN) extraction • CNC/WPI/AN: A new sustainable stabilizer of for Pickering emulsion (PE) • Enhanced physical stability of PEs with dual/triple complexes over CNC or WPI alone • Amphiphilic surface properties of AN-loaded CNC/WP complexes for PE stabilization • Pro-oxidant activity of AN-incorporated CNC/WP complexes in PEs