Convective solar drying of spinach leaves

Abstract

The drying on of the means is usually used which allows the conservation of the food products by lowering of the activity of water. This paper presents the results of an experimental spinach (Spinacia oleracea) drying study in a new solar dryer. It is an indirect solar dryer with forced convection was developed and improved at the Food Science laboratory. Drying spinach leaves to a final moisture content of 2% from 93.2% (wet basis), with an air-drying speed equal to 1m/s. This study made it possible to determine the drying kinetics of spinach leaves, the evolution of the temperature profile and the influence of drying air recycling (0, 50 and 90%) on drying time. The curves of drying obtained show that the drying rate increased marginally with the increase in fraction of air recycled. It is reduced 3 to 4 hours, by increasing the fraction air recycled from 50 to 90 % respectively, with a significant profit of thermal energy. The drying temperature is higher and stable in the drying chamber of the order of 55 to 65°C (90% air recycled).