Abstract: In this study, millet starch was extracted by alkaline extraction, and hydrophobically modified with octenyl succinic anhydride (OSA). The structure of the native and modified starches was characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. It was found that the OSA group was successfully introduced into millet starch, resulting in no change in the crystal structure of starch. The effects of the degree of substitution of starch, starch granule concentration and the proportion of oil phase on the properties of Pickering emulsion were analyzed by measuring emulsification index, emulsion droplet size and rheological properties. The results showed that the emulsifying properties of millet starch were greatly improved after the modification. Emulsification index increased with the increase in starch granule concentration and the proportion of oil phase, while emulsion droplet size decreased with the increase in starch granule concentration and increased with the increase in the proportion of oil phase. Emulsion stability increased with increasing starch granule concentration and the proportion of oil ratio. The rheological analysis indicated that the emulsion may form an internal network structure with a gel-like behavior.

Key words: millet starch; octenyl succinic anhydride; modification; Pickering emulsion; emulsifying properties