Design, construction and testing of a walnut huller

The rapid removal of green skin and drying is an important stage of walnut in post harvesting process. The existence of Tanen in the walnut green skin which brings about fast oxidation, makes it dark and hard for removal. This would cause color change in walnut as well, resulting lower quality. In the present study, the mechanical properties of walnut skin was measured to determine required energy for shearing, crippling and penetrability process for the four most consuming genotypes (called K72، Z67، Pedro، Serr). Preliminary results led to innovation of a mechanism for skin removal and results showed an average of 93 percent success where rotational speed for wire heckle was 368 rpm, the distance of grasp cylinder was 12 mm and removal time was 60 seconds. The optimum reloading time was 15 seconds for 25 to 50 nuts (3-5 kg) and the machine capacity was obtained within 120-240 kg/hr.