Moisture-dependent physical properties of caper (Capparis ssp.) fruit

This study was carried out to determine the effect of moisture content on some physical properties of caper (Capparis ssp.) fruit. Four levels of moisture content ranging from 71.85% to 82.93% w.b. were considered in this study. The fruit length increased from 8.50 to 8.96 mm, width from 7.54 to 8.23 mm, its thickness from 5.67 to 6.90 mm, the geometric mean diameter from 7.13 to 7.96 mm, the sphericity from 0.83 to 0.89, the surface area from 1.59 to 2.00 cm2, the one thousand fruit volume from 156 to 391 cm3 and thousand of fruits mass from 143 to 273 g, increased, while the true density decreased from 916.66 to 598.2 kg m−3, bulk density increased from 394.30 to 424.69 kg m−3, the porosity decreased from 56.98% to 39.17% and the angle of repose increased from 14.84° to 18.05°. The coefficients of static and kinetic friction slightly decreased with the increases in moisture content for all the materials. The highest static and kinetic coefficient of friction were observed on plywood surface, followed by metal sheet, galvanized steel sheet, and rubber materials. This is due to the properties of friction surfaces. This trend may be due to the smoother and more polished surface of galvanized steel and rubber materials compared to metal steel and plywood. The fruits stick more to the friction surfaces as water content decreases.