Abstract: The conditions for extracting pigment from purple potato storage roots were studied. The results showed that the characteristics of this pigment are similar to those of the general anthocyan pigments. So, acid polar impregnant can be use to extract the pigment. The response surface methodology was used to evaluate the factors affecting extraction of pigment from purple potato based on single factor test. The optimum conditions are established as follows: material-to-solution ratio 1:30 (g/ml), HCl concentration 1.1% (V/V), exacting temperature 54.8 ℃ and exacting time 1 hour. Under these conditions, the twice-extracting rate of pigment reaches 93.78%.

Key words: purple potato, pigment, extraction, respond surface methodology