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Evaluation of an Adsorbent for the Removal of Aflatoxin M1 from Contaminated Milk
Lactating cows that consume aflatoxin B1 (AFB1) contaminated feed containing approximately 20 parts per billion (ppb) may produce aflatoxin M1 (AFM1) contaminated milk that exceeds the FDA maximum allowable limit of 0.5 ppb. Current detoxification methods for the reduction of AFM1 include the use of sequestering agents added to feed. The sequestering agents act as an enterosorbent to ameliorate the toxicity of AFB1 by reducing intestinal absorption. However, not all AFB1 is bound and the residual can be metabolized to AFM1. Once this tolerance level of 0.5 ppb AFM1 is surpassed, the milk must be discarded because it cannot be used for human consumption resulting in economic losses.
The current study examines the proficiency of an adsorbent, powdered activated carbon (PAC) to bind AFM1 in various milk types as PAC has excellent adsorption properties in an aqueous environment. A total of 24 samples (r = 3) contained artificially spiked AFM1 (0.5 ppb) and 0.1%, 0.25%, and 0.4% PAC in whole, skim, and raw milk. Samples were shaken, extracted using Agilent QuEChERS extraction salts, and analyzed via liquid chromatography with mass spectrometry detection. A concentration of 0.5 ppb AFM1 was spiked into 10 mL to yield a final concentration in whole (0.54 ± 0.07 ppb), skim (0.46 ± 0.01 ppb), and raw milks (0.56 ± 0.03 ppb). The highest concentration of PAC (0.4%) resulted in a significant decrease in AFM1 contamination (p < 0.05) with a reduction of 65% (0.18 ± 0.08 ppb), 91% (0.05 ± 0.01 ppb), and 52% (0.24 ± 0.03 ppb) of AFM1 from the whole, skim, and raw milks, respectively. No milk showed any significant difference in percent protein, lactose, or total fat relative to their milk blanks (p > 0.05) suggesting that PAC has no effect on milk constituents. Preliminary results show that the use of PAC can reduce the amount of AFM1 below the FDA safety limit and, as a result, prevent the dumping of milk.
Keywords: AFM1, activated carbon, milk