The possibility of making soft drinks with yacon juices was examined. Colorless, transparent and almost odorless juices were obtained by 5 % activated carbon powder treatment. Some adsorbents and ion exchange resins were added in the clear juices to improve flavor and taste. Sensory evaluation found no evident difference. After this, the juices treated with 5% activated carbon powder were used. Adjustment of acidity was performed with citric acid and malic acid. Comparatively favorable sensory evaluation was gained when powders of citric acid and malic acid mixed at the ratio of 2: I were added to the juice at the concentration of 0.4% (w/v). The yacon juices were heated for sterilization at 90'C for 5, 15 and 30 minutes. Fructo-oligosaccharides were degraded markedly by the 30-minute heating. The higher the degree of polymerization in fructo-oligosaccharides became, the larger its rate of decrease became. Also, an adverse change in flavor occurred due to Maillard reaction.