Mechanical strength and physical behavior of pumpkin seed and its kernel.

This study was carried out to evaluate the effect of moisture content (4-20% d.b.) and variety (two common Iranian varieties of pumpkin seeds namely Zaria and Gaboor variety) on physical behavior and mechanical strength of pumpkin seed and its kernel. With the increase of moisture content from 4 to 20% d.b., all the main dimensions (length, width and thickness), equivalent diameter, sphericity, porosity, true density, terminal velocity and absorbed energy increased for both studied variety, while bulk density and rupture force decreased with an increase in moisture content. The ranges of equivalent diameter for pumpkin seed and its kernel were 6.38-9.11 and 5.42-8.27 mm, respectively. The true density of pumpkin seed and its kernel varied from 700.8810.61 and 1064.6-1225.31 kg m -3 , respectively. Also, the range of bulk density at different moisture levels for seed and kernel were obtained between 390.8-525.42 and 550.3-629.7 kg m -3 , respectively. The seeds required less compressive force to dehull when loaded under the horizontal as compared to the vertical orientation. But for kernels, the trend was the opposite. Also, the compressive forces needed to initiate rupture of pumpkin seed hulls were higher (20.1-102.4 N) than those required to rupture the kernel (14.1-37.84 N) in both orientations.