Mathematical modelling of fluted pumpkin seed drying kinetics

Abstract

In this study, the drying characteristics of fluted pumpkin seeds were examined at hot-air temperatures of 50ºC, 60ºC and 70ºC and a constant air velocity of 1.5m/s. Two slicing thicknesses, 5mm and 10mm, were used for the experiment. The results revealed that drying took place during the falling rate period. The moisture ratio, drying time, effective diffusivity and activation energy were affected by drying air temperature and slice thickness. Moisture diffusivity was found to increase with an  increase in drying temperature from 6.6 x 10^-6 to 28.43 x 10^-6 m²/s. Activation energy decreased from 6.72 to 4.02KJ/mol as slice thickness increased from 5mm to 10mm. Drying data were fitted to Page, Modified Page, Henderson & Pabis and Lewis models. All the models studied exhibited good fit to the drying kinetics data of fluted pumpkin seeds, with coefficient of determination (R²) above 0.92 and root mean square error (RMSE) below 1.0. However, the Page model gave the highest R² value (0.998), lowest RMSE value (0.01716) and lowest SEE value (0.0008). This shows that the Page model is the best model to describe the drying behaviour of fluted pumpkin seeds.