Abstract: A series of one-factor-at-a-time experiments were conducted to investigate the effects of four process conditions including sucrose concentration, dehydration time, temperature, ultrasonic powder on water loss and solid gain. These process conditions were further studied using response surface methodology to maximize water loss and minimize solid gain. By their effects on water loss and solid gain, the process conditions could be ranked in the same descending order as follows: dehydration time＞temperature＞sucrose concentration＞ultrasonic powder. The optimal dehydration conditions obtained by response surface analysis were osmotic dehydration temperature of 65 ℃, osmotic dehydration time of 2.46 h, sucrose concentration of 56.29 %, and ultrasonic powder of 142.33 W. In practice, these conditions were modified to be 65 ℃, 2.5, 56% and 140 W, respectively to obtain a water loss of 40.79% and a solid gain of 8.33%.

Key words: purple sweet potato, osmotic dehydration, ultrasonic, response surface methodology