Preparation of the immobilized laccase remover with modified montmorillonite for the removal of aflatoxin B₁

In this study, the removal agent of modified montmorillonite immobilized laccase (MMT-CTAB-Lac) was prepared for the removal of Aflatoxin B₁ (AFB₁). After the treatment of cetyltrimethyl ammonium bromide (CTAB), the MMT-CTAB-Lac was prepared by the modified montmorillonite (MMT-CTAB) with the immobilized laccase. The adsorption kinetics of the removal agent was investigated by the equation fitting. The conditions for removing AFB₁ from the MMT-CTAB-Lac were optimized. The AFB₁ degradation pathway and the toxicity of its degradation products were investigated by the LC-MS and T.E.S.T software. After the modification, the remover had larger layer spacing and pore volume, smaller particle size, and the increased specific surface area for the AFB₁ adsorption. The AFB₁ adsorbed on the remover was degraded by the immobilized laccase, which effectively prevented the accumulation of AFB₁ on the remover, and significantly increased the adsorption capacity of MMT-CTAB-Lac. The chemisorption was a rate-limiting step in the adsorption process of AFB₁. The adsorption capacity of MMT-CTAB-Lac for AFB₁ was 44.5 mg·g^-1, which was higher than that of MMT-CTAB. The removal rate of AFB₁ by the MMT-CTAB-Lac was 67%, with the high catalytic degradation rate under the weak acid and neutral condition. The degradation of AFB₁ by MMT-CTAB-Lac was further identified. The two possible degradation pathways were proposed: the first possible degradation pathway (destruction of lactone ring structure), with the degradation products of C₁₇H₁₄O₇ and C₁₆H₁₂O₅; the second possible degradation pathway (destruction of furan ring structure), with the degradation products of C₁₇H₁₄O₇, C₁₆H₁₂O₇, and C₁₄H₁₀O₄. Through the toxicity prediction of T.E.S.T software, the toxicities of degradation products were reduced. The MMT-CTAB-Lac developed in this study lays an important foundation for the safe and efficient removal of AFB₁ in the field of grain, oil and food.