Impact of ultra-high pressure on the microstructure, emulsification, and physicochemical properties of rice starch.

Ultra-high pressure (UHP) treatment is considered a non-thermo physical treatment technology with a "clean label". Starch is an ideal stabilizer for food-grade Pickering emulsions. This study aimed to investigate the effects of ultra-high pressure (UHP) modification of rice starch on its structure, water/oil absorption, and emulsification properties under different pressure treatments (100-500 MPa), the results showed that the morphology of the starch granules and crystalline structure did not change significantly at lower pressures. Conversely, the particle size of starch increased significantly from 4.85 to 110.13 μm, the relative crystallinity (RC) obviously decreased from 18.89 % to 9.18 %, and the starch granules were destroyed and formed more fragments at higher pressure (500 MPa). The results of water/oil absorption indicated that the oil absorption slightly increased under UHP treatment, but water absorption intensively increased under higher pressure (500 MPa). The emulsifying capacity was significantly enhanced at 500 MPa after 8, 16, and 24 min. The UHP treatment induced swelling and disruption of starch granules at higher pressure (500 MPa). The starch fragments and the released starch molecules stabilized the droplets. This study provides a reference for the application of UHP processing in the starchy foods.