Detergents are steadily becoming one of the necessities in our daily life. However, synthetic detergents are threatening the global environment and human health, as most of them are derived from petrochemicals. Inspired by one of the ancient Asian traditions that the rice-washing water served as a natural detergent for bathing and washing, this work provides insights into the mechanism of the detergent effect of rice-washing water. It is proposed that starch granules existing in the rice-washing water are interfacially active, which can facilitate the formation of O/W Pickering emulsions. This principle is successfully extended to rice flour that is made by mechanical media milling in a large scale. Pickering emulsions loading different organic solvents as dispersed phase can be stabilized by these food-grade granules without adding other chemical additives. Practical trails of removing pesticide residues and meat cleaning confirm the possibilities to render these natural rice starch granules as sustainable assurance.