Abstract
Carcinogenic aflatoxins can be inactivated by smectites (e.g., montmorillonite) through adsorption and degradation. Proteins in gastric fluids can reduce smectite’s adsorption capacity for aflatoxins. The objective of this study was to evaluate the efficiency of smectites modified with organic nutrients in restricting the influence of proteins on aflatoxin adsorption. Arginine, histidine, choline, lysine, and vitamin B1 were selected to occupy part of the interlayer space of montmorillonite to achieve a smectite structure more selective for aflatoxin adsorption, but not for the large protein molecules. The unmodified montmorillonite had a maximum adsorption capacity of 0.2 mol/kg in the presence of pepsin. The vitamin B1-montmorillonite showed significant improvements in the aflatoxin affinity constant from 0.065 to 0.201 M and the aflatoxin adsorption to 0.56 mol/kg. Choline-montmorillonite and histidine-montmorillonite showed a moderate increase in AfB1 adsorption. Arginine-montmorillonite and lysine-montmorillonite showed a slight increase in the adsorption capacity, but did not improve the affinity constant. The XRD results indicated that pepsin could still access the interlayer of nutrient-montmorillonite complexes. The intercalation of organic nutrients into the interlayer space of montmorillonite improved the AfB1 adsorption by restricting the adsorption of pepsin.
Highlights
Aflatoxins are carcinogenic secondary metabolites produced by fungi Aspergillus
Variable temperature X-ray diffraction analysis demonstrated that aflatoxin molecules were adsorbed in the interlayer space of smectites and occupied the hydrophobic sites [4]
It was observed that the valence and size of the exchangeable cation influenced the adsorption capacity and affinity for aflatoxin molecules: the divalent cations had stronger ion–dipole interaction with the carbonyl groups on the AfB1 molecule than the monovalent cations
Summary
Aflatoxins are carcinogenic secondary metabolites produced by fungi Aspergillus. Numerous adsorption experiments have demonstrated that smectites have a high adsorption capacity for aflatoxin.Montmorillonites can adsorb up to 20% (by mass) of aflatoxin. Aflatoxins are carcinogenic secondary metabolites produced by fungi Aspergillus. Numerous adsorption experiments have demonstrated that smectites have a high adsorption capacity for aflatoxin. Montmorillonites can adsorb up to 20% (by mass) of aflatoxin. Animal experiments have shown that smectites can effectively reduce aflatoxin toxicity by adsorbing aflatoxins in the gastrointestinal tract when incorporated into an aflatoxin contaminated feed [1,2,3]. Variable temperature X-ray diffraction analysis demonstrated that aflatoxin molecules were adsorbed in the interlayer space of smectites and occupied the hydrophobic sites [4]. It was observed that the valence and size of the exchangeable cation influenced the adsorption capacity and affinity for aflatoxin molecules: the divalent cations had stronger ion–dipole interaction with the carbonyl groups on the AfB1 molecule than the monovalent cations. Cations with smaller hydration radii induced greater adsorption because less water was brought into the interlayer
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