Optimization of process variables for drying of cashew nuts by superheated steam

Abstract

Cashew is an important economic crop in international market. Thermal processing of cashew nut is essentially an optimization problem. In this work, influence of drying of cashew kernels with testa using superheated steam on product color change and process energy consumption was simultaneously investigated and optimized using response surface methodology. Three independent process variables: temperature (120–140°C), velocity (1–3 m/s), and drying duration (5–30 min) were considered. Box–Behnken design of experiments was employed to obtain the optimum process conditions. It was shown that the second-order polynomials were adequate for the regression model. The coefficient of determination (R2) for the color difference and energy consumption were found to be 0.964 and 0.864, respectively. The color difference and energy consumption were also observed to be a linear function of steam temperature, velocity, and drying duration. For superposition of maximum yield of kernel and other quality indices, optimum thermal processing condition of superheated steam drying was found at 30 min of drying duration, 4 m/s velocity and 115°C temperature of steam.