Underestimation of matrix-bound aflatoxin B1 in pressed peanut cake: Investigating the binding and dissociation mechanisms

First evidence of restricted-release, matrix-bound AFB1 in PPC was proved. • Protein binding is the primary reason for AFB1 hide in PPC. • Matrix hydrolysis or force dissociation effectively releases bound AFB1. • Vitro digestion pretreatment hydrolyzed the matrix, improving detection accuracy. • Highlights critical exposure underestimation for AFB1 in protein-rich samples. Pressed peanut cake (PPC) is a valuable plant protein resource but is highly susceptible to aflatoxin B1 (AFB1) contamination. Its complex matrix can complicate the accurate analysis of AFB1. Digesting the samples in vitro prior to quantification resulted in a significant improvement in AFB1 detection value (25.81–39.40%) compared with untreated samples. Ultrafiltration analysis confirmed that conventional extraction solvents are susceptible to severe interference from the matrix. Molecular docking demonstrated that AFB1 can form complexes with the matrix. Protein hydrolysis leads to significantly higher detection values than starch or cellulose hydrolysis, a phenomenon attributed to the dominant role of protein in binding the toxin. Peanut protein entraps and locks AFB1 through synergistic hydrophobic and hydrogen bonding interactions, forming restricted matrix-bound AFB1. The study elucidated on the formation/ dissociation mechanism of matrix-bound AFB1 in PPC at the molecular level, emphasizing the underestimation of the actual exposure level of AFB1 in PPC. Download: Download high-res image (254KB) Download: Download full-size image