Incandescent Lamp-assited Convective Drying of Potato Slices: Optimization Using RSM

This research focuses on the application of response surface methodology (RSM) in the optimization and mathematical modeling of potato slice drying in a laboratory-scale convective dryer assisted by incandescent lamps. The relationships between the independent variables in terms of temperature (°C), incandescent lamp power (W), and slice thickness (mm) were studied in relation to the responses of interest or dependent variables, consisting of drying time (min), overall product acceptance, and effective water diffusivity (m2s-1). A high value of overall product acceptance is considered to be the optimizing parameter for drying potato sheets. The response surface methodology was applied using a rotational central composite design (RCCD) to optimize the dependent variable. Second-order polynomial regression equations were obtained for each response variable. The optimal drying conditions were established for the maximum value of overall acceptance and were: 69.33 °C, 328.80 W, and 4.40 mm, for temperature, power, and thickness, respectively, with the optimized drying time for the product being approximately 130 min. Drying was carried out during the decreasing drying rate period, and the results show that the addition of energy from incandescent lamps reduces the drying time by 30%. Using the Quasi-Newton Simplex method, the constants of the mathematical models were determined to simulate the drying curve, and the conjugate model of two terms and five constants presented the best fit. Using Fick's law equation, the effective diffusivity of water ranged from 4.48x10-10 to 3.38x10-9 m2s-1, and under optimal drying conditions, it was 2.46x10-9 m2s-1. The information obtained contributes fundamentally to the development of dryers and the control of drying processes on a commercial and industrial scale.