Some physical properties of wild pistachio (Pistacia vera L.) nut and kernel as a function of moisture content

In order to design equipment for improved processing of wild pistachio (Pistacia vera L.), some of the engineering properties were determined as a function of moisture content. The average length, width and thickness of wild pistachio nuts at 5.83% moisture content (w.b.) were 13.98, 8.76 and 7.25 mm, while the corresponding values of kernels at 6.03% moisture content (w.b.) were 11.07, 5.92 and 4.83 mm, respectively. The bulk and true densities of wild pistachio nut and kernel increased with increase in moisture content, while porosity decreased. At all moisture contents, the static coefficient of friction was the highest for wild pistachio nut and kernel on rubber and the least for glass. The results of this research indicated that the filling and emptying angle of repose of nuts and kernels increased as the moisture content increased in the range studied.