modeling and optimization of the effect of osmo-ultrasonic pretreatment followed by hot air drying of black cherry fruit

response surface methodology (rsm) was employed to determine the optimum processing conditions leading to maximum anthocyanin, phenolic compound and antioxidant activity during osmo-ultrasonic pretreatment followed by hot air drying of black cherry fruit. temperature (40, 50 and 60ºc), sucrose content (40, 50 and 60% w/v) and ultrasound frequency (0, 65 and 130 khz) were the factors investigated with respect to anthocyanin, phenolic compound and %ec50 during osmo-ultrasonic pretreatment followed by hot air drying of fruit. experiments were designed according to central composite design with the three factors each at three different levels. the experiments were conducted with solution to sample ratio of 10/1 (v/w). with respect to the dependent variables, both linear and quadratic effects of all the three independent variables on anthocyanin, phenolic compound and %ec50 were found to be significant (p