Abstract The greatest pistachio producer and exporter country in the word is Iran. Within the fifteen years ago, the average product of this kind of fruit has been 232000 tons per year, which it constitutes almost 52.5% of the world production. Fine processing, post processing and transportation of pistachio, have great effects on its quality, food value, physical properties and marketability of this product. Then any applicable research for processing of pistachio, have direct and indirect effects on developing technology of this industry and as a result, farmers can get more income. In this study, various methods of pistachio hulling using a systematic design method have been carefully investigated and after that, new suitable and multipurpose machine for pistachio processing has been presented that can do hulling, washing and dehydrating processes simultaneously. In order to hull pistachio in this machine, centrifugal force is used. The unit consists of two main parts: the hulling set and the power transmission system. The hulling set consists of a rotating drum and a separate rotating circular base – plate. These two parts rotate in opposite directions, employing two separate electrical motors. Some of the advantages of this new machine are simple mechanisms, avoiding from using any complex part, capability of automation, simple usage, simple maintenance and finally low cost of the machine.

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