Enhanced emulsifying properties of corn starch nanoparticles modified with purple corn cob anthocyanins as a Pickering emulsion gel stabilizer

The strong hydrophilicity of corn starch nanoparticles (CSNPs) limits their application as a Pickering emulsion gel stabilizer. In this study, CSNPs were modified with purple corn cob anthocyanins (PCCAs), a type of anthocyanin derived from processing waste. Fourier transform infrared spectroscopy and X-ray diffraction analyses confirmed that PCCAs were embedded in CSNPs via both hydrogen bonding and hydrophobic interactions. The three-phase contact angle increased from 51.77 ± 3.18° to 67.43 ± 1.08° after loading, suggesting the PCCA-modified CSNPs (PCCA-CSNPs) were more suitable than the CSNPs for stabilizing oil/water emulsion. The Pickering emulsion gel stabilized by PCCA-CSNPs (PCSPEGs) exhibited better storage stability than the Pickering emulsion gel stabilized by CSNPs (CSPEGs). A comparison of the rheological properties, creep-recovery properties, and interfacial properties between CSPEGs and PCSPEGs revealed that the combined effects of the more stable interfacial layer and the increased viscosity of the continuous phase of the emulsion gel contributed to the improved stability of PCSPEGs. Thus, PCCA-CSNPs represent a green, rapid, and economical hydrophobic modification method for CSNPs, and the stabilization mechanism of PCSPEGs was elucidated in this work.