Physical properties of sunflower seeds

Physical properties of sunflower seeds and kernels were evaluated as a function of moisture content. At 6.2% m.c.d.b., the average length, width, thickness and unit mass of the seed were 9.52 mm, 5.12 mm, 3.27 mm and 0.049 g respectively. Corresponding values for the kernel were 8.28 mm, 4.09 mm, 2.43 mm and 0.034 g. The mean equivalent diameter and sphericity of the seed were 5.39 mm and 0.57 respectively, while corresponding values for the kernel were 4.32 mm and 0.53. In the moisture range from 4-20% d.b., the bulk density of the rewetted seed decreased from 462 to 434 kg/m(3), true density increased from 706 to 765 kg/m(3), porosity increased from 34.3 to 43.3% and terminal velocity increased from 5.8 to 7.6 m/s. For the kernel the corresponding values changed from 574 to 628 kg/m(3), 1050 to 1250 kg/m(3), 45.4 to 50.2% and 3.5-5.8 m/s. In the same moisture range the static coefficient of friction varied from 0.40 to 0.58 for seed and from 0.43 to 0.81 for kernel on different surfaces, while the angle of respose varied from 34 to 41 degrees for seed and 27 to 38 degrees for kernel. (C) 1997 Silsoe Research Institute.