Encapsulation of β-carotene in chitosan Pickering nanoemulsion: Effect of process parameters and their stability

β-carotene, a vital carotenoid, is limited by poor solubility and stability. Though Pickering nanoemulsions offer superior protection for β-carotene than conventional nanoemulsions, developing food-grade Pickering nanoemulsions remains challenging due to particle size and amphiphilicity issues. This study developed a food-grade Pickering nanoemulsion stabilized by chitosan nanoparticles via high-power ultrasonication. Under optimized conditions (pH 6.5, 2 % oil phase, 1.0 wt% chitosan, 455 W ultrasonication for 180 min), a stable nanoemulsion of 388 nm was obtained with minimized β-carotene loss. These nanoemulsions exhibited exceptional environmental stability, maintaining robust stability under varying pH (3.0-7.0), ionic strength (100-500 mM NaCl), and thermal stress. Thermal stability and extended storage tests demonstrated superior β-carotene protection compared to conventional Tween 20-stabilized emulsions. This work provides a novel strategy for food-grade Pickering nanoemulsions, enabling β-carotene application in functional foods and pharmaceuticals.