PHYSICAL AND MECHANICAL PROPERTIES AND INFLUENCE OF DRYING TECHNIQUES ON DRYING CHARACTERISTICS AND SOME QUALITY PARAMETERS OF MALABAR SPINACH (BASELLA ALBA L.)

摘要

The aims of this research were to measure of some physical and mechanical properties and investigate the influence of drying methods on changing of drying kinetics as well some quality properties of Malabar spinach (Basella alba L.). For these purposes, Malabar spinach (Basella alba L.) was grown in climate-controlled laboratory conditions. Then, the leaves of plant were dried either microwave method or convective hot air drying method. For hot air drying process, three drying temperatures (40, 50 and 60°C) were applied. Three power levels (180, 360 and 600W) were applied for microwave drying process. Mechanical (laceration force, puncture force) and physical properties (leaf lenght, leaf area, stalk thickness, leaf thickness, and initial weight) of fresh Malabar spinach plant samples were measured. Some analyzes such as color (L~*, a~*, b~*), water activity of fresh and dried plant were made to determine quality changes with drying processes. The mean leaf laceration force was determined as 0.0435 kgf while the puncture force value was determined as 0.0144 kgf for fresh leaf samples. Hot air drying process lasted 31, 17 and 6.5 hours for 40, 50 and 60°C drying temperatures, respectively. Microwave drying process took 7.5, 5.5 and 4 minutes for 180, 360 and 600W power levels, respectively. L~* and a~* values of the samples increased while b~* values decreased after all drying applications. Final moisture content values of all dried products were determined between 10.9% and 16%. a~w values of all dried samples were determined lower than the critic level that allows mold growth (a~w <0.6).