A Study on Drying Characteristics, Color, and Vitamin C Preservation of Green Banana Slices Using a Vacuum Heat Pump System

Abstract

Abstract This study aimed to evaluate the characteristics related to the removal of moisture from green banana slices and the effect of the drying conditions on color and vitamin C preservation using a drying system based upon the use of a vacuum heat pump. The green banana slices underwent drying at 40, 50, and 60°C with vacuum pressure levels of 0, 40, and 80 kPa. The average drying time decreased by 18.9% and 32.7% as the vacuum pressure and temperature increased, respectively. Six thin-layer models underwent assessment to explain the kinetic process involved in moisture removal using the vacuum heat pump set to provide differing experimental circumstances, and fitted to experimental data. Results showed that the characteristics of moisture removal from the green banana slices could most appropriately be explained by the Page model. There is in increase in effective moisture diffusivity, which ranged from 1.1658×10−10 to 1.9717×10−10 m2·s−1, with increases in temperature and vacuum pressure. Energy of activation ranged from 15.99 to 19.73 kJ·mol−1, which was explained by an exponential expression based on the Arrhenius models. The drying temperature of 50°C under a vacuum pressure of 80 kPa could preserve the vitamin C content by a maximum of 55.9%, which is the optimal drying condition for obtaining good product quality.