Dual-function natural biopolymers for aflatoxin M₁: adsorption and diagnostic applications in milk

This study investigated the hypothesis that a natural biopolymer system could simultaneously mitigate and detect aflatoxin M₁ (AFM₁) contamination in milk. AFM₁, the hydroxylated metabolite of aflatoxin B₁, is a potent carcinogen that remains stable during milk processing and continues to pose significant food safety concerns. The research therefore aimed to determine the prevalence of moulds and AFM₁ in raw buffalo and cow milk from Giza Governorate, Egypt, and to evaluate the performance of a novel natural biopolymer complex composed of chitosan, β-cyclodextrin, AFM₁-specific antibodies and anthocyanins, designed for dual functionality in AFM₁ adsorption and diagnostic signal enhancement. Total mould counts were assessed following the ISO protocol, while milk composition and somatic cell count (SCC) were determined by Bentley 150 scan. AFM₁ detection was initially performed by thin-layer chromatography (TLC) and subsequently quantified by a validated reversed-phase high-performance liquid chromatography (HPLC) method. The HPLC method exhibited excellent performance with linearity (R² = 0.99999), sensitivity (LOD 0.002 µg/L, LOQ 0.007 µg/L) and precision (RSD ≤ 1.5%). The lowering in milk compositional quality was statistically significant (P < 0.05) with elevated SCC in AFM₁-positive samples. Screening revealed AFM₁ contamination in 28% of buffalo and 56% of cow milk samples, with mean concentrations of 0.084 µg/L and 0.188 µg/L, respectively. Application of the natural biopolymer achieved AFM₁ reductions of 65-73% in buffalo milk and 83-90% in cow milk, while anthocyanins within the polymer provided concentration-dependent diagnostic signals. Sensory evaluation indicated that treated milk maintained acceptable organoleptic properties without adverse effects on compositional quality. These findings emphasise the prospective use of natural biopolymers as dual-function analytical and mitigation tools for AFM₁ in milk, offering a reliable approach for routine milk safety monitoring.