Abstract: The current study aimed to use response surface methodology to optimize process parameters for the osmotic dehydration of yacon under the assistance of ultrasonic. A series of one-factor-at-a-time experiments were conducted to investigate the effects of thosmotic dehydration time and temperature, ultrasonic power, sucrose concentration and ultrasonic treatment time on water loss (WL) and solid gain (SG). Further, quadratic regression orthogonal rotation combination design was used to model WL, SG and WL/SG ratio with respect to thosmotic dehydration time and temperature, sucrose concentration and ultrasonic treatment time, and the three models developed were analyzed by response surface methodology. Ultrasonic assistance was found capable of enhancing the smotic dehydration of yacon. In terms of the importance in affecting WL, the four investigated process parameters ranked in the following order: osmotic dehydration temperature, osmotic dehydration time, sucrose concentration, and ultrasonic treatment time, and the order for affecting SG was osmotic dehydration time, ultrasonic treatment time, osmotic dehydration temperature, and sucrose concentration, and for affecting WL/SG ratio osmotic dehydration time, sucrose concentration, ultrasonic treatment time, and osmotic dehydration temperature. The optimal ultrasonic-assisted osmotic dehydration parameters were osmotic dehydration temperature of 41 ℃, osmotic dehydration time of 1.7 h, sucrose concentration of 60.18 %, and ultrasonic treatment time of 35 min. Under the optimal process conditions, An average SG/WL ratio of 0.059 was achieved.

Key words: yacon, osmotic dehydration, ultrasound wave, response surface methodology