Machine Vision System for Automated Detection of Aflatoxin-Contaminated Pistachios

The previously reported [Pearson, T. Lebensm. Wiss. -Technol. 1996, 28 (6), 203-209] channel image sorter has been used to re-sort color-sort and hand-sort rejects and to sort mainstream (pre-handsort) U.S. pistachios. Sorting was carried out at commercial speeds of up to 163 kg/channel/h. Recoveries of good nuts of 39-67% on re-sorted product and 97.8% on mainstream nuts were achieved. Aflatoxin levels were reduced from 8.6-4.8 to 0.04-2.5 ng/g on color-sort rejects and to 15 from 22 ng/g on hand-sort rejects. For mainstream product, aflatoxin levels were reduced from 0.12 to 0 ng/g by image sorting, compared to reduction to 0.04 ng/g by hand sorting. Quality for mainstream sorting improved significantly, particularly for other damage, serious insect damage, gross defects, and loose kernels. Re-sort quality improved as well, but recovered product will still require dyeing. The sorter should find application in product recovery, in preparation of product for very stringent markets [Schatzki, T. F. J. Agric. Food Chem. 1998, 46 (1), 2-4], and in presorting the very large samples required for testing lots with high reliability, that is, low standard error of the mean [Schatzki, T. F. J. Agric. Food Chem. 1998, 46 (1), 2-4].