Effect of Hot Air Drying Temperature on Drying Kinetics, Physico-Chemical Properties, and Energy Consumption of Culture Asparagus (Asparagus officinalis L.)

Abstract

Influences of drying air temperatures on drying time, specific energy consumption as well as product quality of culture asparagus were investigated in hot-air drying. The drying properties of asparagus samples were performed in a laboratory scale convection dryer at three different temperatures. The drying times of asparagus samples were found as 1200, 630 and 510 min for 50, 60 and 70 °C, respectively. In regard to the data obtained, Midilli et al. model is superior to other models to describe drying behavior of asparagus samples. The effective moisture diffusivity values of asparagus samples were calculated between 6.32 ∙ 10⁻⁹−1.62 ∙ 10⁻⁸ m²/s and the activation energy was estimated as 43.59 kJ/mol. The highest rehydration content and the least total color change were found in asparagus slices dried at 50 °C. Energy consumption values for asparagus samples dried at 50, 60 and 70 °C temperatures were obtained as 10.14, 5.32 and 4.31 kWh, respectively. In terms of energy consumption values, the best efficiency among all drying temperatures was obtained at 70 °C. It has been determined that the specific energy consumption decreased with increasing temperature.