Separation of Aflatoxin-Contaminated Kernels from Sound Kernels by Hydrogen Peroxide Treatment

Blends (0:1, 1:3, 1:1, and 3:1, wt/wt) of aflatoxin-contaminated and sound peanut kernels were submerged for 1, 2, and 3 min in various concentrations of hydrogen peroxide solution. The effectiveness of these treatments in separating aflatoxin-contaminated kernels from sound kernels was determined. Peanuts that floated (floaters) and those that did not (sinkers) were subjected to aflatoxin analysis. Second order polynomial equations were satisfactorily fitted to the experimental data. Hydrogen peroxide concentrations of 0.075, 0.150, and 0.25% resulted in a reduction in aflatoxin content in the kernels in the sinker fraction by 90% within 1 min, regardless of the initial aflatoxin content. The total aflatoxin content in sinker and floater fractions was approximately the same as that in unfractionated samples, indicating that the low concentrations of hydrogen peroxide in treatment solutions did not degrade aflatoxin. Response surface methodology was used to generate contour plots which revealed optimum treatment conditions for giving a maximum yield of the sinker fraction with low aflatoxin content. For peanuts containing 50 ppb aflatoxin, optimum conditions consist of a 0.08% hydrogen peroxide treatment for 0.7 min. This procedure results in a maximum sinker fraction yield of 85.5% of the original lot with a residual aflatoxin content of ≤5 ppb.