Effect of Cleaning Corn on Mycotoxin Concentration

Mycotoxins are fungal secondary metabolites from molds grown on cereal grains and other commodities. These molds may produce aflatoxin B₁, which is carcinogenic to humans and animals. Mycotoxins are often concentrated in cracked or broken kernels because there is exposed substrate for mold growth. Removal of this material has been demonstrated to reduce the concentration of mycotoxin, but the reduction is highly variable. Most literature has used artificial mycotoxin contaminated grain to limit variability. Therefore, the objective of this experiment was to quantify the magnitude of natural mycotoxin concentration that may be reduced by cleaning corn in a traditional grain handling facility setting. 10 mT of corn naturally contaminated with aflatoxin (1,074 ppb), fumonisin (8.3 ppm), and ochratoxin A (206 ppb) was procured from central Oklahoma to evaluate the role of cleaning to reduce mycotoxin concentration in corn. After receiving regulatory approval to transport it, the corn was cleaned at the biosafety level-2 feed mill at Kansas State University. 3,000 kg of corn were divided into twenty 150 kg runs, which were then cleaned using a commercial corn cleaner (Gentle Roll, EBM Manufacturing, Norfolk, NE) to remove overs (material > 12.7-mm) and thrus (material < 4.76-mm) to establish 3 treatments: 1) unclean corn; 2) cleaned corn; and 3) screenings (overs + thrus). The corn cleaner was sanitized between each of the 20 runs. Three 5-kg samples of corn were collected by probing from each treatment of each run, ground via hammermill, riffle divided, and analyzed for mycotoxin concentration using multiclass liquid chromatography tandem mass spectrometry. Data were analyzed using the GLIMMIX procedure of SAS, as a completely randomized design with run as the experimental unit. Within run, cleaned corn contained lower aflatoxin and fumonisin quantity than unclean corn despite the variability in quantity across run number. Cleaning generated approximately 6% screenings, and reduced (P < 0.05) aflatoxin concentration by an average of 26% (1,074 vs. 789 ppb aflatoxin for unclean vs. cleaned corn, respectively). Cleaning also reduced (P < 0.05) fumonisin concentration by 45% (8.3 vs. 4.5 ppm fumonisin for unclean vs. cleaned corn, respectively), but did not impact ochratoxin A. Screenings had nearly 4 times the aflatoxin (4,224 ppb) and 7.5 times the fumonisin concentration (60.4 ppm) as uncleaned corn. These data suggest that cleaning is an effective method to legally reduce aflatoxin and fumonisin concentration, but the resultant screenings should be used cautiously when feeding to animals.