Humic Acids Preparation, Characterization, and Their Potential Adsorption Capacity for Aflatoxin B in an In Vitro Poultry Digestive Model.

Vermicompost was used for humic acid (HA) preparation, and the adsorption of aflatoxin B (AFB) was investigated. Two forms of HA were evaluated, natural HA and sodium-free HA (SFHA). As a reference, a non-commercial zeolitic material was employed. The adsorbents were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), energy-dispersive X-ray spectroscopy (EDS), zeta potential (ζ-potential), scanning electron microscopy (SEM), and point of zero charge (pHpzc). The adsorbent capacity of the materials when added to an AFB-contaminated diet (100 µg AFB/kg) was evaluated using an in vitro model that simulates the digestive tract of chickens. Characterization results revealed the primary functional groups in HA and SFHA were carboxyl and phenol. Furthermore, adsorbents have a highly negative ζ-potential at the three simulated pH values. Therefore, it appears the main influencing factors for AFB adsorption are electrostatic interactions and hydrogen bonding. Moreover, the bioavailability of AFB in the intestinal section was dramatically decreased when sorbents were added to the diet (0.2%, /). The highest AFB adsorption percentages using HA and SFHA were 97.6% and 99.7%, respectively. The zeolitic material had a considerable adsorption (81.5%). From these results, it can be concluded that HA and SFHA from vermicompost could be used as potential adsorbents to remove AFB from contaminated feeds.