Optimization of drying conditions for steamed-dried sweet pumpkin products using response surface methodology

In this study, sensory evaluation was performed to select the pretreatment method for dried sweet pumpkin products, and the drying conditions were optimized by using response surface methodology (RSM). Based on the results of the sensory evaluation, the steaming method was selected for pretreatment. To optimize the drying conditions of the steamed sweet pumpkin products, the temperature (30, 40 and 50°C) and duration (4, 6 and 8 h) of hot-air drying were set as independent variables, and moisture content, water activity, soluble solids, strength, hardness, and free sugar contents were set as dependent variables. In the process of optimization, moisture contents, water activity, and soluble solids were designated as optimization variables by R2 and Pr>F values. The optimum drying conditions were found to be 42°C and 5.7 h. The suitability of the experimental design and model was evaluated by comparing the predicted values with the experimental values measured under optimal conditions. The moisture content and water activity were within the 95% confidence interval. Although the soluble solids contents were out of range, it was calculated to be higher than the predicted interval and appeared closer to the target value. Therefore, it was concluded that the manufacturing conditions optimized in this study were the ideal conditions for drying sweet pumpkin products.