The extraction method of pigment from purple sweet potato using phosphoric acid aqueous solution asextracting solvent was compared with citric acid aqueous solution. The extraction conditions including concentration ofphosphoric acid or citric acid, solid- liquid ratio, extracting time were investigated by single factor experiment andorthogonal experiment, respectively. Results indicated that the effect of purple pigment extracted by phosphoric acidaqueous solution with a lower concentration and a shorter extracting time was better than that of...