Abstract: The optimal extracting technology of yam bean polyphenols was studied by the fractional factorial design, as well as two kinds of determination methods were compared. The results were as following: When the FC was used, the optimal extracting conditions were ethanol concentration 75.3%, ratio of the ethanol to HCl 98.3:1.7, temperature 82.5 ℃, and ratio of material to solvent 1:30. Under these conditions the highest extracting rate was 11.1615 mg/g. When the Prussian blue was used, the optimal extracting conditions were ethanol concentration 70%, ratio of ethanol to HCl 97.6:2.4, temperature 96 ℃, ratio of material to solvent 1:30. Under these conditions the highest extracting rate was 4.4503 mg/g.

Key words: yam bean polyphenol, extraction, fractional factorial design, determination methods