design, construction and evaluation of wild pistachio sheller

the wild pistachio (pistacia atlantica mutika) exists in 2.4 million hectares of iranian forest. in spite of high nutritional and medical value of this fruit, its use and processing are still performed manually. the objectives of this research are to design, to construct and to evaluate the performance of a pistachio hulling machine. the pistachio of kerman province was chosen as the case of study. the mechanism of shelling was chosen based on the applied pressure force of two cylinders, driving and driven. the effects of input variables including revolution of driving cylinder (three levels), the gap between two cylinders (four levels) and moisture content (four levels) on the performance of machine (shelling efficiency, percentage of intact kernel, percentage of imperfective broken nut, percentage of dust, and percentage of unshelled nut) were analyzed. the results showed that the shelling efficiency decreases with increasing the gap of two cylinders and moisture content of wild pistachio. the maximum intact kernel was obtained at moisture content of 6.61 wb %. the best performance was observed with the following conditions: the cylinders’ gap of 0.48 mm, rotational speed of the driving cylinder of 25.84 rpm and moisture content of 4.31% w.b.