The Effects of Moisture Content on Physico-Chemical Properties of Confectionary Sunflower Seeds

The study of physicochemical and mechanical characteristics of sunflower seeds are important when the designing of control equipment’s, transportation, processing, and product storage are concerned. In this study, physicochemical and mechanical characteristics of four varieties of confectionary sunflower seeds were evaluated. Some of the assessed physicochemical and mechanical properties include: the content of total ash, fat, and minerals and also the mean length, width, thickness, diameter, sphericity, surface area, volume, 1000-grain weight, angle of repose, porosity, particle density and bulk density, hull and kernel percentage, coefficient of friction surface and axial compression test. The results showed that the highest amount of fat content (48%) and potassium content (76.639 mg per kg) were found in  sample number 3; and highest amount of  ash content (3.83%) and sodium content (25.318 mg per kg) were found in sample number 4. Physical properties of sunflower seeds were studied in five moisture content levels of 4% to 32% (based on dry basis weight). The results reaealed increasing trend in length, width, thickness, sphericity, geometric and arithmetic mean diameter, surface area, volume, 1000-grain weight, angle of repose, porosity and density upon increasing moisture content; while, bulk density decreased. The coefficient of static friction of all seeds at glass, chipboard, galvanized, and aluminum surfaces increased with the increase in moisture content. When the moisture content increased from 4 to 32 percent, the highest increase in the coefficient of static friction was observed in sample number 3 with aluminum surface and the lowest increase in the coefficient of static friction was observed in sample number 1 with glass surface. Based on results obtained from the axial compression test, the vertical loading force was found to be more than that the horizontal loading force and in all samples, the total vertical and horizontal loading forces were decreased by increasing the moisture content.