Nano/Submicrometer milled red rice particle-stabilized Pickering emulsions and their antioxidative properties.

Nano/Submicrometer red rice particles were obtained through processing a type of red rice using media milling. The particle size of red rice was gradually reduced with the increasing of milling time. After milling time of 4 h, the particle size of milled red rice was reduced to around 692 nm. Microscopic observation and SEM analysis confirmed the presence of nano/submicrometer particles. The phytochemicals content of milled red rice was analyzed. The total anthocyanin content of red rice increased after milling process. Its phenolic and flavonoid content were slightly decreased after the milling process. All milled red rice exhibited good ferric reducing antioxidant property (FRAP) and DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging activity. The emulsifying ability of milled red rice particles with different milling time was characterized. Milled red rice starch particles with concentration of 0.8~3.5% were able to form stable Pickering emulsions. And milled red rice particle retarded the oil oxidation process when being used to stabilize Pickering emulsions. It is a pioneer study that directly modifies whole grain materials as colloid particles to form food grade Pickering emulsions with intrinsic antioxidant properties.