Some physical properties of Karingda [Citrullus lanatus (Thumb) Mansf] seeds

Some physical properties of karingda seed and kernel were evaluated as a function of moisture content. The average length, width, thickness and mass of 100 seeds were 10 . 60 mm, 6 . 18 mm, 2 . 37 mm and 0 . 099g respectively at a moisture content of 7 . 35% d.b. Corresponding values for the kernel were 8 . 85 mm, 4 . 88 mm, 1 . 64 mm and 0 . 062 g. In the moisture range from 5 to 40% d.b., studies on rewetted seed showed that the bulk density of seed and kernel increased from 487 to 595 kg/m(3) and 501 to 646 kg/m(3) respectively. The true density of kernel increased from 1010 to 1134 kg/m(3), while for seed, it decreased from 1148 to 1004 kg/m(3). The porosity decreased from 57 . 6 to 40 . 7% and 50 . 4 to 43 . 0% for seed and kernel respectively. The terminal velocity for both seed and kernel increased from 4 . 5 to 6 . 5 and 3 . 5 to 48 m/s respectively. In the same moisture range, the static coefficient of friction of seeds against surfaces of three structural materials varied from 0 . 91 to 0 . 34 with plywood, 0 . 80 to 0 . 29 with mild steel and 0 . 67 to 0 . 23 with galvanized iron. The corresponding values for kernels were 0 . 79 to 0 . 33, 0 . 69 to 0 . 27 and 0 . 67 to 0 . 22. The angle of repose increased from 28 to 42 deg for seed and 31 to 43 deg for kernel with an increase in moisture content from 5 to 22% d.b. (C) 1996 Silsoe Research Institute.