Technical Note: Characteristics and Sorting of White Food Corn Contaminated with Mycotoxins

Abstract

White corn grown in southern Texas was collected for characterization and evaluation of the feasibility of sorting kernels containing mycotoxins. Kernels were grouped into one of six symptom categories depending on the degree of visible discoloration and bright green-yellow fluorescence (BGYF) or bright orange fluorescence (BOF). Kernels visibly discolored (= 25% of their surface) and having BGYF contained over 57% of the aflatoxin. However, kernels approximately 50% discolored without BGYF contained over 35% of the aflatoxin. Over 33% of the fumonisin was found in kernels that were visibly discolored and had BOF. The remaining fumonisin was in asymptomatic kernels at low levels. Sorting tests for removing mycotoxin-contaminated kernels were performed using a dual wavelength high-speed commercial sorter. In one pass through the sorter, aflatoxin was reduced by an average of 46%, and fumonisin was reduced by 57% while removing 4% to 9% of the corn. Re-sorting accepted kernels a second time resulted in an 88% reduction in aflatoxin while removing approximately 13% of the corn. Approximately half of the aflatoxin missed by the optical sorter was found in larger kernels showing BGYF but no other symptoms, with the remaining aflatoxin in smaller kernels where the germ was damaged by insect feeding.