The development of a softdrink using a purple potato 'Shadow Queen' was investigated. Purple potato juice was efficiently obtained by 0.1% amylase and pectinase decomposition of a mixture of 1 volume of steamed potatoes with 4 volumes of water. The juice contained a large amount of reducing sugars and some oligosaccharides. Sugar and acid were added to the juice was performed to adjust taste, flavor, and color stability. As a result, a juice with a good taste and flavor was obtained when its composition was adjusted to Brix 8 and its sugar/acid ratio to 19. Moreover, the purple color of the juice was almost unchanged by heat treatment at 80℃ for 30 min for sterilization. The present study revealed the feasibility of developing a novel softdrink made from purple potatoes.
