Engineering morphology and surface chemistry of starch nanoparticles for Pickering emulsions in non-dairy coffee creamers

This study explores the use of starch nanoparticles (SNPs) as Pickering emulsion stabilizers. SNPs were synthesized by recrystallizing short-chain glucan (SCG) from debranched starch and further modified into oxidized rod-shaped SNPs (Ox-SNPs) through selective anisotropic oxidative etching. Scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) confirmed differences in morphology, functional groups, and structure. Emulsification performance was assessed under varying pH (3–10), ionic strength (0–50 mM NaCl), and wettability. While SNPs showed sensitivity to acidic conditions and salt, Ox-SNPs remained stable due to surface carboxylation, which enhanced electrostatic repulsion. Contact angle analysis revealed increased hydrophobicity in Ox-SNPs (72°) as compared to SNPs (60°), attributed to both oxidation and a higher aspect ratio (∼2 for Ox-SNPs vs. ∼1 for SNPs), which enhanced interfacial adsorption and packing. Notably, only Ox-SNP-stabilized emulsions retained stability in hot (80 °C) acidic coffee solutions, suggesting potential for food applications.