Cellulose Nanocrystals-Stabilized Acidic W₁/O/W₂ Emulsions for Anthocyanins Encapsulation

The limited stability of anthocyanins restricts their application in the food industry, necessitating encapsulation to prevent degradation. This study fabricated an anthocyanin-rich acidic water-in-oil-in-water (W₁/O/W₂) emulsion system stabilized by cellulose nanocrystals (CNCs). Anthocyanins extracted from the by-product peels of 'France' Prunus domestica L. were incorporated into the inner aqueous phase (W₁). The internal phase (W₁/O) ratio was increased to 40% (w/w) to enhance anthocyanin loading capacity. CNCs were sonicated to reduce their size and improve their interfacial properties, thereby enhancing the emulsifying capacity. Sonicated CNCs combined with whey protein isolate (WPI) significantly improved double emulsion performance compared to the non-sonicated CNCs-WPI system: (1) reduced D₄₃ from 8.50 µm to 4.35 µm; (2) elevated ζ-potential from 7.49 ± 0.99 mV to 10.07 ± 1.50 mV; and (3) improved encapsulation efficiency from 52.96 ± 2.60% to 83.39 ± 0.96%. Furthermore, encapsulated anthocyanins exhibited significantly enhanced thermal stability compared to free anthocyanins, with the half-life at 50 °C increasing from 14.72 ± 0.35 h to 70.37 ± 0.51 h. This study demonstrates that modifying nanoparticle interfacial properties provides valuable insights for designing stable emulsions and enhancing anthocyanin stability.