Investigation of moisture content effect on physical properties of Russian olive fruit (Elaeagnus angustifolia L.)

This study was conducted to investigate some moisture-dependent engineering properties of Russian olive fruit including fruit dimensions, one thousand seed mass, surface area, sphericity, bulk and true density, angle of sliding and static friction coefficient against different surfaces. The physical properties of Russian olive fruit were evaluated as a function of moisture content in the range of 5.75-30.48% d.b. The average length, width, thickness and one thousand seed mass were 18.11 mm, 12.56 mm, 12.2 mm and 102 g, respectively at moisture content of 5.75% d.b. The geometric mean diameter and sphericity increased from 13.68 to 14.01 mm and 75.57 to 76.03% as moisture content increased from 5.75 to 30.48% d.b., respectively, while bulk density decreased from 440.52 to 423.12 kgm⁻³ in the same moisture range, true density increased from 854.12 to 936.25 kgm⁻³, and the corresponding porosity increased from 48.42 to 54.8%. As the moisture content increased from 5.75 to 30.48% d.b., the angle of sliding, terminal velocity and surface area were found to increase from 26.5 to 32.5º, 6.1 to 6.32 ms^-1 and 587.62 to 616.31 mm², respectively. The static coefficient of friction increased on three structural surfaces namely, glass (0.286-0.356), stainless steel (0.344-0.419) and plywood (0.305-0.375) in the moisture range from 5.75 to 30.48% d.b.