The Fate of Aflatoxin in Corn Fermentation

A lab-scale ethanol fermentation was investigated to determine where aflatoxin concentrated during each phase of production. Four corn samples with high levels of aflatoxin (ranging from 7750 17,208 parts per billion) and their replicates were compared with a replicated negative control. Fractions were taken from the fermented mash, distilled ethanol, stillage, and dried corn solids (DCS). These fractions were analyzed using two different immunoassay methods and liquid chromatography tandem mass spectrometry (LC-MS/MS). Results indicated no aflatoxin was found in the distilled ethanol. Some aflatoxin (13%) was detected in the stillage, but most of the toxin was recovered in the DCSs ranging from 31% to 58%. A second series of experiments were conducted to investigate the effect of binders on dried distillers grains (DDGs). A brewers dried yeast anti-caking binder that contains glucomannon (MTB-100), was mixed with contaminated DDGs. Addition of the binder showed a significant reduction in aflatoxin levels in comparison to a positive control. Aflatoxin binding at 2% binder w/w reached 72.5% and showed a minimal binding percentage increase of 80% at 6% binder w/w. Testing was also conducted to determine if environmental variables such as pH and temperature had any effect on the binding capabilities. Temperature near 0 ̊C resulted in binding at 19.7% at a pH range of 6 to 8. Additionally, at a temperature of 40 ̊C resulted in binding of 36%, 47%, and 45% at pHs 6, 7, and 8, respectively. These findings suggest that the addition of sorbents may be an effective way of salvaging contaminated DDGs.