Application of response surface methodology for optimization of hazelnut drying under infrared fluidized bed

Most of agricultural products are harvested in high moisture level which is not suitable for storage. Therefore, to prevent deterioration, drying operations are performed on them. In this study, hazelnut kernels were dried in an infrared fluidized bed dryer. To determine the optimized conditions of the hazelnut samples, response surface methodology and Face-Centered Central Composite Design (Face-CCD) were used to investigate the effect of temperature levels (45, 65 and 85 °C), air velocity levels (1.30, 3.09 and 4.87 m/s) and infrared power levels (500, 1000 and 1500 W) under infrared fluidized bed dryer. The adequacy and accuracy of the fitted models (lack of fit and R2) were checked with analysis of variance (ANOVA). Response surfaces and contour plots were created to show the interaction between the independent variables and the response variables (effective moisture diffusivity, consumption energy, shrinkage and the total color difference). Based on the experiments, the optimum conditions for the maximum values of effective moisture diffusivity and minimize values of consumption energy, shrinkage and ∆E (total color difference) were applied. According to the results in infrared fluidized bed dryer, the optimum conditions were determined at air temperature of 48.96°C, air velocity of 1.53 m/s and infrared power of 500W. The optimum values of the response variables affecting the effective moisture diffusivity, consumption energy, shrinkage and the total color difference (∆E) were obtained 3.13×10-10 m2/s, 18.76 kWh, 11.17% and 3.71, respectively.