Optimization of hot air drying of purple sweet potato using response surface methodology

Abstract

Recently, the interest in purple sweet potato has increased due to its high nutrients content. In order to improve the drying quality of purple sweet potato, in this study, response surface methodology (RSM) was used to optimize operating conditions of the purple sweet potato in a hot air drier and quadratic polynomial regression models were used for the optimization. Optimization factors were slice thickness(2-6mm), air velocity(1-2m/s) and temperature(45-55°C) while investigated responses were energy consumption per unit mass, value of chromatism and loss rate of anthocyanins and comprehensive assessment. The order of strength of the factors affecting the drying process and the best value of factors when drying purple sweet potato were determined to obtain. The order was found to be air velocity first, temperature second, and then slice thickness and the best values of factors were found to be slice thickness of 5.11mm with air velocity of 1.88m/s for the temperature of 55°C. At this the best point, the responses were found of 0.073KWh/g, 12.88, 22.20%, 0.96, respectively. This study provides a theoretical basis for further study on hot-air drying equipment and technology for purple sweet potato.