Low Cost Real-Time Sorting of In-Shell Pistachio Nuts from Kernels

Abstract

A simple, low-cost optical system and decision making circuitry for use in high speed sorting devices designed for separating pistachio nuts with (in-shell) and without (kernels) shells is reported. Testing indicates 95% accuracy in removing kernels from the in-shell stream with no false positive results out of 1000 kernels tested. Testing with 1000 each of in-shell, shell halves, and kernels resulted in an overall error of about 3.3%, roughly twice the overall error rate achieved using a commercially available dual band NIR-VIS sorting device. However, the cost of materials for the equipment reported here was less than $500 (U.S.), indicating the potential for economical sorting versus for commercially available equipment. Since existing sorters can be trained to sort a variety of product streams, implementation of the new device in pistachio plants could free up machines for other sorting tasks, thus reducing the overall cost of sorting the pistachio crop.