Prediction of mass transfer parameters and thermodynamic properties using the refractance Window™ technique for drying of Yam (Dioscorea Trifida) paste

Abstract

Dioscorea trifida tuber contains starch, vitamins, minerals and bioactive compounds. It is perishable, requiring dehydration treatment to increase shelf life. This study aimed to investigate the mass transfer parameters and thermodynamic properties of Dioscorea trifida using Refractance Window (RW) drying (70, 80, and 90 °C). It was observed that the dehydration process occurred in a short time (40 min). The moisture diffusivity and the mass transfer coefficient were determined using the Dincer and Dost model. The diffusivity coefficients ranged from 2.62 × 10-6 at 6.13 × 10-6 m2 s-1, the mass transfer coefficient ranged from 3.46 × 10-4 at 4.04 × 10-4 m s-1 and the estimated of activation energy was 44.091 kJ mol-1. In the Dioscorea trifida Refractance Window drying, the enthalpy and entropy are positive and negative, respectively, decreasing with increasing temperature and thus indicating that the process is endothermic. Gibbs free energy increases with increasing temperature, indicating that the process does not occur spontaneously.