Optimization of convective drying by response surface methodology

In this work, response surface methodology (RSM) is applied to state an optimized system for convective drying of apple slices using desirability function. The interaction of the independent parameters including air temperature (T = 70–90 °C), air velocity (V = 4–5 m/s), and apple slice geometry (G = circle, square, and triangle) with the dependent variables consist of drying time, energy consumption, and shrinkage is determined. Minimum drying time, energy consumption and shrinkage is regarded as the optimizing drying conditions of apple slices. Experimental results are adapted by a second-order polynomial model where analysis of variance is utilized to define model compatibility and optimal drying conditions. The optimal conditions of combined optimized responses were 90 °C inlet temperature, 5 m/s inlet velocity, and square geometry which designated by maximum desirability function (D = 0.781). The air temperature had a notable influence on total responses, but the effect of air velocity and apple slice geometry were important in shrinkage. Generally, the results marked that a greater desirability value could be obtained in the higher air temperature and higher air velocity with the square geometry.